Peter Marra: Energizing the Base

It’s hunting season, a fitting time for Peter Marra to be reiterating his call for the killing of outdoor cats. Earlier this week he delivered the keynote address at the annual conference of the Ohio Community Wildlife Cooperative, and tonight he’ll be in Baraboo, Wisconsin, presenting “Cats, Birds and You: Keeping Cats Indoors.”

This latest stop on Marra’s Extermination Nation tour is a homecoming of sorts. It was at the nearby University of Wisconsin–Madison, in the early 1990s, that the modern witch-hunt against outdoor cats began with the infamous Wisconsin Study. Using little more than cocktail napkin guesswork, UWM professor Stanley Temple and graduate student John Coleman “estimated” that outdoor cats killed up to 219 million birds in rural Wisconsin alone. [1] Although Marra’s “estimates” are significantly higher, his (flawed) methods—and motive—are striking similar to Temple’s.

(Fun fact: The two were among 10 authors—including Nico Daphiné, Marra’s former post-doc, who was forced to resign after she was found guilty of trying to poison cats—of a 2010 letter calling for conservation biologists to “counter trap-neuter-return.” [2])

Nearly eight years later—and faced with more pushback than he’d apparently expected—Marra’s still reworking his message for mainstream audiences. Look past the media-friendly rhetoric* and cowardly back-pedaling, though, and his call to action (just like Temple’s) is unchanged: the killing of cats on an unprecedented level. Read more

Thinking Inside the Box

It’s difficult to determine how these things get started—how the results of a well-documented experiment conducted nearly 40 years ago become twisted into the frequently made—and widely-accepted—claim that “even well-fed cats hunt.”

This would appear to be a case of validity through repetition: repeat a claim often enough and, eventually, people will come to believe it’s true—never bothering to check the original source. (Pro Tip: For added efficacy, click the heels of your ruby-red slippers together while repeating the claim.)

This, it should go without saying, is not how science is supposed to work. Read more

Stanley Temple Endorses Smithsonian/USFWS Paper

It came as some surprise, a couple weeks ago, to learn that Stanley Temple was a guest on WHYY’s Radio Times, discussing the Smithsonian’s “killer cat study.” (Full disclosure: I’ve yet to listen to the episode.) Temple was, as I’m sure most readers know, the man behind the infamous Wisconsin Study (from which, not surprisingly, Scott Loss, Tom Will, and Peter Marra borrow for their own “estimate”), so his position on the issue is no surprise.

What surprised me (as I’ll explain below) was that he wanted to weigh in publicly.

And then, a week-and-a-half later, Temple was doing it again, with an opinion piece in Friday’s Orlando Sentinel (where, on that same day, Alley Cat Allies co-founder and president Becky Robinson, called the Smithsonian/USFWS paper “wildly speculative” in an op-ed of her own). Read more

Fight or Flight?

“Cat Fight,” which appears in the latest issue of Conservation magazine, does little to cut through the rhetoric or clear up the numerous misrepresentations that plague the debate over free-roaming cats.


There is, it’s often said, no such thing as bad PR. Even so, I’m not thrilled with the way I’m portrayed in an article appearing in the current issue of Conservation. It’s only a couple of quotes, but still, I worry that I come off as more of a bomb-thrower than anything else.

“Wolf writes a blog, Vox Felina,” explains writer John Carey, in “Cat Fight,” “which regularly excoriates wildlife biologists for what Wolf calls their ‘sloppy pseudo-science.’ He charges that ‘the science in Dauphine’s paper about cats was so horrific that she should have never made it out of graduate school’ and that ‘Peter Marra is taking six bird deaths and predicting the Apocalypse.’”

As I told Carey via e-mail, just after the piece was published online, I don’t believe the quotes are accurate. Carey, on the other hand, assures me (in a cordial, professional manner typical of our exchanges) that “the quotes are exactly what [I] said.” (Neither of us recorded our conversation.)

“I know I realized immediately when you said those things that they were precisely the type of colorful statements that illustrate the nature of the debate, so I did appreciate you using such colorful language.”

Fair enough. Perhaps it’s not all the important if the content isn’t precisely correct—the tone is certainly accurate.

If I am a bomb-thrower, though, I am at least a well-informed bomb-thrower. And the “targets”—to extend the metaphor—have, simply put, got it coming to them. Carey acknowledges that I “do an excellent job scrutinizing the scientific evidence, and have clearly thought deeply about both sides of the issue.” Unfortunately, that doesn’t come across to Conservation readers.

That said, I want to make it clear: I’m grateful to have been included in the piece, and grateful, too, for my conversations with Carey. And whatever quibbles I have about my portrayal pale in comparison to various other aspects of “Cat Fight.”

Stuffing the Ballot Box
Referring to Peter Marra’s well-publicized catbird study, Carey writes: “Predators nabbed nearly half the birds, and cats were the number one predator.” [1]

Number one predator?

Certainly, this was the message Marra emphasized to the press—but I thought I’d straightened this out with Carey on the phone, and with a follow-up e-mail.

Here’s what Marra and his colleagues report in their paper:

A total of 69 fledglings were monitored, of which 42 (61 percent) died over the course of the study. Of those mortalities, 33 (79 percent) were due to predation of some kind. Eight of the 33 predatory events were observed directly: six involved domestic cats, one a black rat snake, and one a red-shouldered hawk.

That leaves 25 predation events (76 percent) for which direct attributions could not be made—which, in and of itself, raises serious questions about Carey’s “number one predator” claim.

About those other 25: Marra and his co-authors concede that “not all mortalities could be clearly assigned.” Seven were attributed to rats or chipmunks because they were “found cached underground,” while another one was attributed to birds because the remains were found in a tree.

In addition, 14 mortalities “could not be assigned to a specific predator.” Which leaves three: “fledglings found with body damage or missing heads were considered symptomatic of cat kills.” [2]

In fact, it’s rather well known that such predatory behavior is symptomatic not of cats, but of owls, grackles, jays, magpies, and even raccoons [3–5]—something I addressed in an October 2010 post (and discussed with Carey).

All of which is difficult to reconcile with Marra’s claim, in “Cat Fight,” that he and his colleagues “were very conservative assigning mortality to cats,” [1] and with his apparent confidence (shared by Carey) in putting cats at the top of the list.

Curious, too, that, although Carey opens his article with Nico Dauphine’s December 2011 sentencing hearing, he never mentions the fact that Marra was Dauphine’s advisor at the Smithsonian Migratory Bird Center. (I suppose the connection isn’t something Marra brags about these days.)

The Cats Came Back
Carey argues that “moving cat colonies away from areas that harbor threatened species is a no-brainer” but points out that “it doesn’t always work.”

“In Fortescue, New Jersey, a colony of feral cats was moved away from the shore of Delaware Bay in 2011 to help protect red knots, which stop there in huge numbers to gorge on horseshoe-crab eggs to fuel their long migration from the tip of South America to the Arctic. But after only a few months, cats were back.” [1]

Here, I’ll defer to Animal Protection League of New Jersey attorney Michelle Lerner, whose comment was the first posted after “Cat Fight” was available online:

“The details about the Fortescue cats, with which I was involved, are incorrect. The colony was not ‘moved,’ it was removed completely. 40 cats were moved to a fence enclosure on a farm several counties away, 7 went to a sanctuary in another state, others went to barns or were friendly enough to be adopted. Removal was used, which is what the anti-TNR people always want. The only difference is the cats were not killed—something that was possible because of limited numbers. It is true that, due to the vacuum effect, different cats then showed up. The nonprofit doing the removal keeps trapping there in coordination with animal control to try to get them all. A few per month show up. But this is why TNR advocates warn removal never really works without intensive management and repeat trapping, and why statistical studies have shown it takes 10 times the effort to control a colony through removal as through TNR. Because there is a reason the cats were there in the first place and more will just move in—more who are unneutered—if the cats are removed.”

It’s worth pointing out, too, that, unlike the current relocation effort, taxpayers would be footing the bill for an ongoing lethal roundup.

And I wish Carey had included a bit of additional context here. The greatest threat to those red knots, from what I can tell (admittedly, doing nothing more than a quick Google search), has little to do with cats being fed nearby. According to The Wetlands Institute:

“…overharvesting of female horseshoe crabs by commercial fishermen, coupled with loss of spawning habitat resulting from beach erosion associated with sea level rise, has resulted in a precipitous decline in the Delaware Bay horseshoe crab population, and therefore the number of eggs available to feed migratory birds. This, in turn, has led to a dramatic decrease in the size of annual red knot migrating populations, to the point that red knots have been proposed for federally endangered status.”

Indeed, the Delaware Nature Society reports: “In 2008, New Jersey placed a moratorium on horseshoe crab harvests until the red knot numbers rebound.”

The Scientific Community v. The People of the District of Columbia
If Marra hasn’t come to Dauphine’s defense, Chris Lepczyk has—with the kind of confidence he (and Marra) usually reserve for vilifying free-roaming cats.

“‘I am 100 percent confident she was not poisoning cats,’ says University of Hawaii wildlife ecologist Christopher Lepczyk, who fears that she was convicted in part because of her articles about the cat-predation problem. ‘I don’t think anyone in the scientific community agrees that she is guilty.’” [1]

That’s quite an endorsement—especially in light of… you know, the facts.

On December 14th, the day Dauphine was sentenced, CNN reported that Superior Court Judge A. Truman Morrison III “said he had received a number of letters from people who know Dauphine.”

“He said such letters usually try to make a case that the verdict was in error, but in this case, the judge said, no one quarreled with the guilty verdict… Morrison said it was clear from letters written by Dauphine’s colleagues that ‘her career, if not over, it’s in grave jeopardy.’ The judge said that was already partial punishment for her actions.”

But Lepczyk’s right when he says the verdict was, in part, the result of Dauphine’s writings—just not in the way he suggests. Indeed, the day Dauphine was found guilty, The Washington Post reported: “Senior Judge Truman A. Morrison III said it was the video, along with Dauphine’s testimony, that led him to believe she had ‘motive and opportunity.’”

“He specifically pointed to her repeated denials of her writings. ‘Her inability and unwillingness to own up to her own professional writings as her own undermined her credibility,’ Morrison said.”

All of which—not to put too fine a point on it—was included in my numerous posts following the case. Perhaps Lepczyk ought to subscribe to Vox Felina.

I’ve been saying for nearly two years now that Dauphine’s professional work on the subject of free-roaming cats—cited and promoted with great enthusiasm before all this nasty press attention—is as indefensible as the actions that landed her in DC Superior Court. It’s a shame Carey didn’t pin down Lepczyk (and others) on that point.

Numb and Numb-er
If Carey included me in “Cat Fight” because of my colorful language, I have to imagine Stephen Vantassel, project coordinator of distance education for the University of Nebraska-Lincoln’s School of Natural Resources, was included for his unintended irony.

Referring to the toll cats take on wildlife, Vantassel told Carey, “The numbers are mind-numbing.” [1]

Actually, “mind-numbing” is a fitting description for the content of, and motivation behind, Feral Cats and Their Management, the well-publicized paper Vantassel co-authored in late 2010. Not only do the authors fail to get a handle on the predation numbers, they reveal a significant lack of understanding of the key issues surrounding cats and predation in general. Indeed, they misread, misinterpret, and/or misrepresent nearly every bit of research they reference. And, some of what the authors include isn’t valid research to begin with.

Two years later, it seems he’s still got nothing to contribute to the discussion.

OK, maybe that’s being too harsh. Consider what Vantassel has to say, in the sidebar that accompanies “Cat Fight,” about the uncertainty surrounding the legal status of free-roaming cats: it “has essentially turned outdoor cats into protected predators.” [6]

Protected predators?

Now, here’s a subject Vantassel knows well. After all, his PhD (theology) dissertation was dedicated to: “…fur trappers who, every winter, brave the harsh weather in continuance of America’s oldest industry. Regrettably, they must also endure the ravages of urban sprawl and the derision of an ungrateful and ignorant public.” [7]

Wisconsin: Landmarks and Mirages
My greatest disappointment with “Cat Fight”—one shared by others I’ve spoken with—is Carey’s inclusion of the infamous “Wisconsin Study.”

“In a landmark study in Wisconsin, Stanley Temple, now professor emeritus of forest and wildlife ecology at the University of Wisconsin, and his colleagues radio-collared free-ranging rural cats, watched the animals’ hunting behavior, and examined their stomach contents. (An inflammatory and inaccurate press report that implied that the researchers had killed the cats for the stomach contents—in fact, they used an emetic—led to death threats against Temple.) The study showed that each cat killed an average of 5.6 birds a year. With an estimated 1.4 million free-ranging rural cats just in Wisconsin, that’s nearly 8 million birds.” [1]

When I spoke with Carey, he’d already talked to Temple. And when he referred to a predation study Temple had done, I stopped him in his tracks: If Temple conducted any such work, it was never published.

What has been published involved combining cat density numbers Temple and graduate student John Coleman had gathered by surveying “farmers and other rural residents in Wisconsin for information about their free-ranging (not house-bound) cats” [8] with predation numbers from studies conducted in the 1930s and 1950s. All of which is explained in a 1992 article the two wrote for Wildlife Control Technology:

“…our four year study of cat predation in Wisconsin, completed in1992, coupled with data from other studies, allows us to make a reasonable estimate of birds killed annually in this state… At the high end, are estimates from diet studies of rural cats that indicate at least one kill per cat per day, resulting in over 365 kills per cat per year [9–11]. Other studies report 28 kills per cat per year for urban cats, and 91 kills per cat per year for rural cats [12].” [13]

“Using low values,” then, Temple and Coleman multiplied their estimated 1.4 million rural free-roaming cats in the state by 28 (“twice urban kill rate”), and then multiply that by 20 percent (the “low dietary percent,” as they call it, though it’s actually a gross misinterpretation of Mike Fitzgerald’s work, as Ellen Perry Berkeley points out in her 2004 book TNR Past Present and Future: A history of the trap-neuter-return movement [14]). The resulting “estimate” is “7.8 million birds killed annually.”

Twenty years later, though, the story seems to have changed dramatically.

Now, we’re to believe that Temple and Coleman’s study (funded, by the way, with “about $100,000 … from the [University of Wisconsin], U.S. Agriculture Department and the state Department of Natural Resources” [15]) revealed an average predation rate of 5.6 birds/year/cat. And that the 7.8 million figure comes not from “coupling” Temple and Coleman’s density work with others’ predation studies, but from their work alone.

Or perhaps the two methods resulted in exactly the same estimate.

Which, as I told Carey after reading the article, would be one hell of a coincidence. In fact, the very sources he cites call into question—if not discredit entirely—Temple’s claim.

Simply put: Carey failed to dig into this deeply enough. Instead of further perpetuating the myth of the Wisconsin Study, he might have exposed it for what it is: little more than a few misguided (and overpriced) back-of-the-envelope calculations—which Temple himself backed away from during a 1994 interview with The Sonoma County Independent: “They aren’t actual data; that was just our projection to show how bad it might be.” [16]

Or, failing that, then at least ignore the thing entirely.

Landmark study? Only insofar as it was instrumental in launching what’s become a witch-hunt against free-roaming cats in this country.

•     •     •

According to the magazine’s website, “Conservation stories capture the imagination and jump-start discussion.” Unfortunately, I don’t see “Cat Fight” adding much to the discussion—a missed opportunity in a debate where such opportunities are few and far between.

I agree with Carey that, as he notes in the article’s closing paragraph, “these great societal debates … are contested on a battleground of conflicting emotions, moral values, and ideologies. Facts alone rarely break up the fight.”

On the other hand, I don’t see how we’re going to break it up if we don’t first get the facts straight.

Literature Cited
1. Carey, J., “Cat Fight.” Conservation. 2012. March. http://www.conservationmagazine.org/2012/03/cat-fight/

2. Balogh, A., Ryder, T., and Marra, P., “Population demography of Gray Catbirds in the suburban matrix: sources, sinks and domestic cats.” Journal of Ornithology. 2011: p. 1-10. http://dx.doi.org/10.1007/s10336-011-0648-7

http://nationalzoo.si.edu/scbi/migratorybirds/science_article/pdfs/55.pdf

3. Thompson, B., The Backyard Bird Watcher’s Answer Guide. 2008: Bird Watcher’s Digest.

4. Bird, D.M., “Crouching Raptor, Hidden Danger.” The Backyard Birds Newsletter. 2010. No 5 (Fall/October).

5. Anderson, T.E., Identifying, evaluating and controlling wildlife damage, in Wildlife Management Techniques. 1969, Wildlife Society: Washington. p. 497–520.

6. Carey, J., “The Uncertain Legal Status of Cats.” Conservation. 2012. March. http://www.conservationmagazine.org/2012/03/legal-status-of-cats/

7. Vantassel, S.M., Dominion over Wildlife?: An Environmental Theology of Human-Wildlife Relations. 2009: Resource Publications.

8. Coleman, J.S. and Temple, S.A., “Rural Residents’ Free-Ranging Domestic Cats: A Survey.” Wildlife Society Bulletin. 1993. 21(4): p. 381–390. http://www.jstor.org/pss/3783408

9. Errington, P.L., “Notes on Food Habits of Southwestern Wisconsin House Cats.” Journal of Mammalogy. 1936. 17(1): p. 64–65. http://www.jstor.org/stable/1374554

10. Parmalee, P.W., “Food Habits of the Feral House Cat in East-Central Texas.” The Journal of Wildlife Management. 1953. 17(3): p. 375-376. http://www.jstor.org/stable/3797127

11. Eberhard, T., “Food Habits of Pennsylvania House Cats.” The Journal of Wildlife Management. 1954. 18(2): p. 284–286. http://www.jstor.org/stable/3797736

12. Mitchell, J.C. and Beck, R.A., “Free-Ranging Domestic Cat Predation on Native Vertebrates in Rural and Urban Virginia.” Virginia Journal of Science. 1992. 43(1B): p. 197–207. www.vacadsci.org/vjsArchives/v43/43-1B/43-197.pdf

13. Coleman, J.S. and Temple, S.A., “How Many Birds Do Cats Kill?” Wildlife Control Technology. 1995. July–August. p. 44. http://www.wctech.com/WCT/index99.htm

14. Berkeley, E.P., TNR Past present and future: A history of the trap-neuter-return movement. 2004, Bethesda, MD: Alley Cat Allies.

15. Imrie, R. (1997). Professor Says Predatory Cats Are Taking Toll on Ecosystem. St. Paul Pioneer Press, p. 1B,

16. Elliott, J. (1994, March 3–16). The Accused. The Sonoma County Independent, pp. 1, 10,

Blowback

Oh what a tangled web we weave,
When first we practise to deceive!
Sir Walter Scott

Wind turbine near Walnut, IowaWind turbine near Walnut, Iowa. Photo courtesy of Wikimedia Commons and Bill Whittaker.

Two stories from New York Times writer Elisabeth Rosenthal caught my eye this past Monday. The first, “Tweety Was Right: Cats Are a Bird’s No. 1 Enemy”—the latest recounting of Pete Marra’s catbird research—reads more like a joint press release from ABC and the Smithsonian than it does a Times-worthy science story.

In the second piece, posted on the Green blog, Rosenthal weighs bird mortalities from wind turbines against the number of birds killed each year by cats: 440,000 compared to 500 million.

The figure for wind turbines comes, presumably, from the U.S. Fish & Wildlife Service (USFWS), while the estimate for annual cat kills comes from the American Bird Conservancy (ABC). Interestingly, I’ve been unable to locate anything on the USFWS Website to support the estimate attributed to that organization; in fact, the only place I’ve seen the connection made is on ABC’s Website.

Thanks to one of my devoted (and well-informed) readers, I need to correct this last point. In fact, the USFWS estimate comes from a 2009 paper (PDF available for download here) by Albert Manville, Senior Wildlife Biologist with USFWS.

Not that it makes a great deal of difference, I suppose—I don’t have much confidence in either ABC or USFWS.

Beyond the Numbers
Even setting aside for the moment the questionable accuracy of each mortality estimate, the comparison is still not as straightforward as it first appears. “If your interest is in protecting several iconic American bird species,” suggests Rosenthal, “the whooping crane, the golden eagle and the sage grouse—wind turbines are possibly the bigger problem.”

The greater sage-grouse, a species listed as Near-Threatened, and the whooping crane, officially Endangered, with perhaps fewer than 500 remaining in the wild, are of particular concern.

“In protecting America’s wildlife,” argues Robert Bryce in a 2009 Wall Street Journal opinion piece, “federal law-enforcement officials are turning a blind eye to the harm done by ‘green’ energy.” [1]

Bryce, who, according to his bio, “has been writing about the energy business since 1989,” says oil companies and electric utilities have often been sued under the Migratory Bird Treaty Act. “Yet there is one group of energy producers that are not being prosecuted for killing birds: wind-power companies.” [1]

Like Bryce, Michael Fry, ABC’s Director for Conservation Advocacy, doesn’t care for this double standard. “Somebody has given the wind industry a get-out-of-jail-free card,” he told Bryce. “If there were even one prosecution, the wind industry would be forced to take the issue seriously.” [1]

But there’s a certain irony in Fry’s complaint.

If the wind industry’s been given a “pass,” it’s due in no small part to ABC and their relentless campaign against free-roaming cats. Since at least 1997, when their Cats Indoors! program was launched, ABC has been telling anybody who would listen that free-roaming cats kill an extraordinary number of birds each year.

In so doing, ABC has given the wind industry one of its strongest arguments against making the kinds of changes ABC is now demanding.

The Marketing of the Wisconsin Study
Their undated brochure Domestic Cat Predation on Birds and Other Wildlife, for example, still available on the ABC Website, cites, among other apparently damning evidence, the infamous “Wisconsin Study”: “Rural free-roaming cats kill at least 7.8 million and perhaps as many as 217 million birds a year in Wisconsin. Suburban and urban cats add to that toll.” [2]

Not that ABC hasn’t had help. USFWS, too, has tried its best to legitimize these back-of-the-envelope “estimates,” settling on the researchers’ “most reasonable estimate” [3] of 39 million birds killed each year in Wisconsin for its publications on the subject. [4, 5]

And these efforts have paid off. For years now, news stories of birds killed by wind turbines have referred—sometimes directly, and sometimes not—to predation rates that Stanley Temple himself admitted “aren’t actual data.” [6]

A 2005 U.S. Department of Agriculture Forest Service report cites Coleman and Temple’s work specifically, [7] suggesting that their own “estimate of 100 million birds killed by cats on an annual basis” is therefore “highly conservative” by comparison. [8] According to the report:

“…annual bird mortality from anthropogenic sources may easily approach 1 billion birds a year in the U.S. alone. Buildings, power lines and cats are estimated to comprise approximately 82 percent of the mortality, vehicles 8 percent, pesticides 7 percent, communication towers 0.5 percent, and wind turbines 0.003 percent.” [8]

In Wind Power: Impacts on Wildlife and Government Responsibilities for Regulating Development and Protecting Wildlife, also published in 2005, the Government Accountability Office offers no total for birds killed by wind turbines, but goes into detail regarding several other causes of mortality, including cats (“hundreds of millions of bird deaths”) using data from USFWS. [9]

Industry insiders, too, have been paying attention.

Wisconsin Focus on Energy, for example, uses Coleman and Temple’s figures to “put the situation in perspective”:

“Cats, both feral and domestic, also take their toll on birds. A Wisconsin Department of Natural Resources report [3] states, ‘recent research suggests that rural free-ranging domestic cats in Wisconsin may be killing between 8 million and 217 million birds each year. The most reasonable estimates indicate that 39 million birds are killed in the state [Wisconsin] each year.’” [10]

Laurie Jodziewicz, communications and policy specialist for the American Wind Energy Association (AWEA) offered a similar perspective in a 2009 interview with Mother Earth News: “Even if we got 100 percent of our electricity from wind turbines, bird mortality wouldn’t be even close to that which is caused by communication towers, buildings, automobiles or even cats.” [11]

•     •     •

And the debate continues.

In a news release from earlier this month, ABC challenges AWEA’s estimates:

“The U.S. Fish and Wildlife Service has estimated that approximately 440,000 birds are already being killed each year by wind turbines, yet AWEA continues to assert that the death toll is less than one quarter of this. More importantly, the industry association ignores the fact that wind development is currently a tiny fraction of that proposed for 2030 when it is anticipated to kill a minimum of one million birds annually, and likely many more.”

Still, it’s a difficult argument to make on the basis of the numbers alone.

Perhaps the folks at ABC and USFWS might offer some perspective of their own—pointing out, for instance, that predators, cats included, tend to prey on unhealthy birds [12–15], whereas mortalities from non-predatory events—collisions with wind turbines, for example—tend to include healthy and unhealthy individuals alike. Or that cat owners are increasingly keeping their cats indoors—thus reducing their impact on wildlife. [16—18]

Or that the “Wisconsin Study” numbers are meaningless. Or that context matters.

It’s all true, of course, and it would bolster their case against the growing wind industry. On the other hand, ABC and USFWS would have to do the unthinkable: concede some of the very points TNR advocates have been making for years.

Literature Cited
1. Bryce, R. (2009, September 7). Windmills Are Killing Our Birds. The Wall Street Journal, from http://online.wsj.com/article/SB10001424052970203706604574376543308399048.html

2. ABC, Domestic Cat Predation on Birds and Other Wildlife. n.d., American Bird Conservancy: The Plains, VA. http://www.abcbirds.org/abcprograms/policy/cats/materials/predation.pdf

3. Coleman, J.S., Temple, S.A., and Craven, S.R., Cats and Wildlife: A Conservation Dilemma. 1997, University of Wisconsin, Wildlife Extension. http://forestandwildlifeecology.wisc.edu/wl_extension/catfly3.htm

4. USFWS, Migratory Bird Mortality. 2002, U.S. Fish and Wildlife Service: Arlington, VA. http://www.fws.gov/birds/mortality-fact-sheet.pdf

5. USFWS, Perils Past and Present : Major Threats to Birds Over Time. 2003, U.S. Fish and Wildlife Service: Arlington, VA. http://www.fws.gov/birds/documents/PastandPresent.pdf

6. Elliott, J. (1994, March 3–16). The Accused. The Sonoma County Independent, pp. 1, 10.

7. Coleman, J.S. and Temple, S.A., On the Prowl, in Wisconsin Natural Resources. 1996, Wisconsin Department of Natural Resources: Madison, WI. p. 4–8. http://dnr.wi.gov/wnrmag/html/stories/1996/dec96/cats.htm

8. Erickson, W.P., Johnson, G.D., and Jr., D.P.Y., A Summary and Comparison of Bird Mortality from Anthropogenic Causes with an Emphasis on Collisions (USDA Forest Service Gen. Tech. Rep. PSW-GTR-191). 2005, U.S. Department of Agriculture, Forest Service. www.fs.fed.us/psw/publications/documents/psw_gtr191/Asilomar/pdfs/1029-1042.pdf

9. GAO, Wind Power: Impacts on Wildlife and Government Responsibilities for Regulating Development and Protecting Wildlife. 2005, U.S. Government Accountability Office: Washington, DC. www.gao.gov/new.items/d05906.pdf

10. Sagrillo, M., Wind turbines and birds: Putting the situation in perspective in Wisconsin. 2007, Wisconsin Focus on Energy. http://www.focusonenergy.com/Information-Center/Renewables/Fact-Sheets-Case-Studies/Wind.aspx

http://www.focusonenergy.com/files/document_management_system/renewables/windturbinesandbirds_factsheet.pdf

11. Rogers, A., Do Wind Turbines Really Kill Birds?, in Mother Earth News. 2009. http://www.motherearthnews.com/Renewable-Energy/Do-Wind-Turbines-Kill-Birds.aspx

12. Baker, P.J., et al., “Cats about town: is predation by free-ranging pet cats Felis catus likely to affect urban bird populations? Ibis. 2008. 150: p. 86-99. http://www.ingentaconnect.com/content/bsc/ibi/2008/00000150/A00101s1/art00008

13. Møller, A.P. and Erritzøe, J., “Predation against birds with low immunocompetence.” Oecologia. 2000. 122(4): p. 500–504. http://www.springerlink.com/content/ghnny9mcv016ljd8/

14.  Gill, F.B., Ornithology. 3rd ed. 2007, New York: W.H. Freeman.

15. Klem, D., Glass: A Deadly Conservation Issue for Birds, in Bird Observer. 2006. p. 73–81. http://www.massbird.org/BirdObserver/index.htm

16. Clancy, E.A., Moore, A.S., and Bertone, E.R., “Evaluation of cat and owner characteristics and their relationships to outdoor access of owned cats.” Journal of the American Veterinary Medical Association. 2003. 222(11): p. 1541-1545. http://avmajournals.avma.org/doi/abs/10.2460/javma.2003.222.1541

17. Lord, L.K., “Attitudes toward and perceptions of free-roaming cats among individuals living in Ohio.”Journal of the American Veterinary Medical Association. 2008. 232(8): p. 1159-1167. http://www.avma.org/avmacollections/feral_cats/javma_232_8_1159.pdf

18. APPA, 2009–2010 APPA National Pet Owners Survey. 2009, American Pet Products Association: Greenwich, CT. http://www.americanpetproducts.org/pubs_survey.asp

A House Deluded

On February 25th, the Utah House of Representatives voted rather decisively—44 to 28—in favor of HB 210, which would amend the state’s animal cruelty laws. Whether or not the representatives knew what they were voting for, however, is anybody’s guess.

Listening to the floor debate, one gets the impression there were two—maybe three—different bills up for discussion. Not that House members got any help from sponsor Curtis Oda (R). Indeed, Oda’s rambling, disjointed presentation only muddied the waters further.

Among the bill’s provisions is an exemption for animal cruelty in cases where the individual responsible for harming or killing an animal acted reasonably, in the protection of people or property. Also included—and the source of the greatest controversy—is an allowance for “the humane shooting of an animal in an unincorporated area of a county, where hunting is not prohibited, if the person doing the shooting has a reasonable belief that the animal is a feral animal.”

This Is Not About Cats
Referring to the bad press HB 210 has received over the past few weeks (including a stinging satire on The Colbert Report, which was widely circulated on the Web), Oda was, not surprisingly, defensive.

“It wasn’t about cats; it’s about all animals that are feral—including cats, dogs, pigeons, pigs, whatever it might be… But the cat community has made it a cat issue, so let’s talk cats.”

And talk cats he did.

“Let’s get into some of the other reasons why we need some of this… The U.S. Fish and Wildlife Service—and because it was made into a cat issue, I’m using cats—cites that cats and other introduced predators are responsible for much of the migratory bird loss. Domestic and feral may kill hundreds of millions of songbirds and other avian species every year, roughly 39 million birds annually. They’re opportunistic hunters, taking any small animal available—pheasants, native quail, grouse, turkeys, waterfowl, and endangered piping plovers. Most of these birds are protected species.”

That 39 million figure, of course, comes from the notorious Wisconsin Study, and represents Coleman and Temple’s “intermediate… estimate of the number of birds killed annually by rural cats in Wisconsin.” [1] Nothing more than a “best guess,” as the authors call it, and one based entirely on the predation of a single cat in rural Virginia. [2, 3]

It’s a figure commonly found in U.S. Fish and Wildlife Service (USFWS) publications, [4, 5] and on their Website. (Oda’s not the first one to mistake this for an estimate of predation across the country, however; Frank Gill made the same error in his book Ornithology. [6])

Oda’s choice of bird species surely raised a few eyebrows—at least among those who were paying attention. First of all, a number of the birds are hunted in Utah—which would seem to complicate the predation issue significantly (though, of course, hunters are paying for the “privilege” of killing wildlife).

And those “endangered piping plovers” (technically, listed as “Near Threatened”)? According to the Cornell Lab of Ornithology Website, this “small pale shorebird of open sandy beaches and alkali flats…[apparently, Utah’s salt flats don’t count] is found along the Atlantic and Gulf coasts, as well as inland in the northern Great Plains.”

Another obvious blunder: Oda would have us believe that cats are both opportunistic hunters (which they are) but that they also target rare and endangered species. (But again, Oda’s not alone: USFWS made a similar argument in their recent Florida Keys National Wildlife Refuges Complex Integrated Predator Management Plan/Draft Environmental Assessment.

Economic Impact
Once Oda brought up Wisconsin, it seemed almost inevitable that Nebraska, too, would creep into the debate. It didn’t take long.

“The Audubon magazine recently cited a new peer-reviewed paper by University of Nebraska–Lincoln—researchers concluding that feral cats—domestic that live outdoors and are ownerless—in other words, feral—account for $17 billion—that’s billion—in economic loss from predation on birds in the U.S. every year.”

That $17 million dollar figure (which, apparently, was just too good for the National Audubon Society, American Bird Conservancy, and others to pass up) is based on some very dubious math (indeed, the paper notes that birders spend just $0.40 for each bird seen, whereas hunters spend $216 for each bird shot, suggesting, it seems, that dead birds are far more valuable than live birds—a point NAS and ABC, of course, ignored entirely).

The origins of the figure can be traced to two papers by Cornell’s David Pimentel and his colleagues, [7, 8] in which the authors estimate “economic damages associated with alien invasive species.” [8]

Referring to this work, Hoagland and Jin, resource economists at the Marine Policy Center, Woods Hole Oceanographic Institution, (using the case of the European green crab to make their point) warn: “There are many reasons to be concerned about the use of these estimates for policymaking.” [9] Among their concerns, are the use of potential rather than actual impacts, and the validity of the underlying science—as well as the overall lack of rigor involved in developing such estimates.

“Heretofore, estimates of the economic losses arising from invasive species have been far too casual. Unfounded calculations of economic damages lacking a solid demonstration of ecological effects are misleading and wasteful.” [9]

Predation Estimates
Oda then tried to put the predation into context:

“In Utah alone, if we assume a million households, you can estimate around a third of them have cats—that’s 333,333. If we just add a feral population of at least that many, making it two-thirds of a million—if each cat killed just three birds per year, you can see that the predation is around two million each year.”

Three birds/year is more conservative than what’s used for many back-of-the-envelope estimates, but that doesn’t excuse the flaws in Oda’s calculation—beginning with his suggestion that the number of feral cats in the state equals the number of pet cats. Where’s the evidence?

He’s also assuming that all cats hunt. However, about two-thirds of pet cats don’t even go outside. [10–12]

And then, of course, there’s the issue of impact. Even if Oda’s right about the two million birds, that says nothing about the impact on their populations. Are the birds common? Rare? Healthy? Unhealthy? Etc.

Referring to “Cats and Wildlife: A Conservation Dilemma,” another of the Wisconsin Study papers, [13] Oda continues:

“Nationwide, cats probably kill over a billion mammals and hundreds of millions of birds each year. Worldwide, cats may have been involved in the extinction of more bird species than any other cause except by habitat destruction.”

Again, no mention of impact. And, no mention of where the vast majority of those extinctions took place.  According to Gill’s Ornithology:

“Most (119, or 92 percent) of the 129 bird species that have become officially extinct in the past 500 years are island species. Roughly half of these species were exterminated by introduced predators and diseases. The rest were driven to extinction by direct human exploitation and habitat destruction.” [6]

However isolated Utah may seem at times—politically, socially, and culturally—the state is not an actual island.

Trap-Neuter-Return
For an assessment of TNR, Oda turns not to Alley Cat Allies or to the No More Homeless Pets in Utah program, but to David Jessup, Senior Wildlife Veterinarian with the California Department of Fish and Game:

“David Jessup, a Doctor of Veterinary Medicine, has written that trap, neuter, and release programs are not working as well as it has been touted. I’ve got packets here talking about that. If anybody wants to see it, they’re welcome to that.”

In fact, Jessup offers little to support his own sweeping claim that, “in most locations where TNR has been tried, it fails to substantially or quickly reduce cat numbers and almost never eliminates feral cat populations” [14] Instead, he refers to a paper by Linda Winter, [15] former director of ABC’s Cats Indoors! campaign—and prolific source of misinformation on the subject of TNR.

Oda continues:

“Releasing feral cats back into the wild is actually an unnatural act. They are unnatural predators that compete [for] food with eagles, hawks, owls, ferrets, etc.”

This last point, it would seem, is a reference to the often-cited work of William George, who suggested that “cats inevitably compete for prey with many of our declining raptors, and therein may lie a serious problem.” [16] It turns out, though, that George’s concerns were largely unfounded, as I’ve discussed previously.

No wonder Oda turned to Jessup and Winter for a TNR primer—the man simply doesn’t have a clue:

“Citizens that want to help are often met with expenses and inconveniences that deter them. Many who monitor TNR colonies are not managing them correctly. I had one lady who said she had more than 100 cats that she had saved with TNR, but kept getting new cats almost weekly. She’d been feeding them more than what they could do on their own, thereby attracting new cats.”

I rather doubt that making it legal to shoot at feral cats will somehow make caretakers’ lives easier. And why, if Oda thinks regular citizens are unable to properly manage a colony of feral cats, is he so sure they’ll be able to properly distinguish a feral cat from a pet in the event they want to shoot it?

Oda’s complaint about feeding feral cats—and the idea that this attracts additional cats—is a common one. Cats are remarkably resourceful, and where there are people, there is food. Better to have them part of a managed colony, where they are sterilized—and often adopted, too—than to be under the radar.

The same argument can be made for the alleged relationship between TNR and the dumping of cats. It’s difficult to imagine that the presence or absence of a nearby TNR program would affect a person’s decision to abandon his/her pet cat(s). (If any studies had demonstrated such a connection, TNR opponents would surely cite them.) And, under the circumstances, isn’t it better that they be “enrolled” in a TNR program than the alternative?

“Releasing is also unfair to the rest of the neighborhood,” argued Oda, “who’s adversely affected.”

“It doesn’t affect just the person monitoring. But the problem is much bigger than TNR only. An unspayed female cat can have up to three litters per year, with an average of five kittens per litter, so as you can see, the problem grows exponentially.”

While unrestricted populations will grow exponentially, Oda’s numbers are ridiculous—probably the foundation for the widely debunked 420,000-cats-in-seven-years-myth.

Still think HB 210 isn’t about cats?

A Little Something for Everybody
At this point, Oda’s presentation moves beyond the bogus science and tired, baseless complaints—and pretty well comes off the rails entirely.

“This bill does not replace TNR, but it’s supposed to work potentially in conjunction with TNR, but we need to make sure everybody uses those TNR programs properly. We do have a serious problem with irresponsible owners, and we can’t make it unreasonable for them to take their animals to shelters and animal control facilities… We need to make things a little bit easier for people to help, not just make it easier for them to—” [lost audio]

How open season on feral cats is “supposed to work potentially in conjunction with TNR” is a mystery—and one Oda didn’t have a chance to clear up. At this point, his colleagues give him just one more minute to wrap things up.

“We just need to make it easier for people to be able to do things the right way, instead of making it so ridiculously expensive and inconvenient—so that it’s easier for them to just take their animals and drop them off anywhere else, whether it be cats or dogs, or whatever it may be. Perhaps down the road we might have to have mandatory licensing for cats. We do that with dogs already and the problem with dogs has diminished substantially.”

Huh?

Are we still talking about the same bill here? HB 210 does nothing at all to address dumping, intake policies at shelters, or licensing. The confusion only worsened as several representatives supporting the bill took to the House floor to make their positions known.

Supporters
Rep. Fred Cox
(R), who helped revise the bill, suggested that HB 210 offers a means of controlling the population of feral cats—a complement to TNR programs:

“We spent quite a bit of time reviewing with proposed amendments… We did have the opportunity of listening to a number of individuals speak for and on behalf of various options… You have to decide whether or not it’s a good idea for individuals to purposely release certain animals—sometimes in large quantities into the wild that were not originally designed to be here. There are certain parts of the world that have had problems with this area, and in some cases, we have problems now. This provides us an option. We still have other options that are available—with trap, neuter, and release—those are still on the table. This does not prohibit those methods to be used, but does allow another method to be used.”

For Rep. Lee Perry (R), HB 210 offers a humane approach for dealing with abandoned pets:

“I represent a lot of rural farmers and ranchers, and this bill is critical to them. I can’t have a farmer or rancher going to jail or to prison because they take care of a feral cat or a feral dog that is on their ranch or their farm, that somebody inhumanely took out and dumped out in the middle of western Box Elder County or in western Cache County. When the people go out there and dump their animals, thinking they’re being humane and putting them… out into the wild or onto somebody’s farm, they’re actually harming those animals more than what these farmers or ranchers would be doing in basically being humane, and putting them out of their misery at that point. Because these animals are eventually going to starve to death, in some cases, and die. They’re left in the cold, in the elements. These are usually animals that are meant to be raised in a house, and in a controlled environment. Because of that, I support this substitute bill, and I would ask that the body would support it as well.”

Easily the most interesting account, however, was that of Rep. Brad Galvez (R):

“I had an individual that lives just a few miles west of my home who was basically attacked by a cat—had a cat that scratched him on his hand, and he basically just flung it against the wall. This individual was charged with a third-degree felony.”

A search of several newspapers tells a very different story. Reese Ransom, 85, was actually charged with aggravated animal cruelty—a misdemeanor—when he severely injured a feral kitten. When Ransom picked up the kitten—one of a litter he and his wife had been feeding—to bring it inside:

“It went wild, like cats do,” he said. “It was scratching and biting. It was hanging from my hands with its teeth, so I just pitched it away to get rid of it. It hit the garage and knocked it out.” [17]

According to Ogden’s Standard–Examiner, Weber County Sheriff’s Deputy Bryce Weir witnessed the event. “Weir’s report said Weir got out of his patrol car and walked to the garage, noting the kitten was still alive, but barely moving.” [18]

The kitten was eventually euthanized.

The Animal Advocacy Alliance of Utah pushed for Ransom to be changed with a felony, but were unsuccessful.

But Galvez, who—don’t forget—lives just a few miles east of Ransom, completely misrepresents the facts of the case to his colleagues. There’s no telling whether or not his “interpretation” of events had any bearing on the eventual vote, but it raises questions about the man’s integrity.

Opponents of HB 210
HB 210 had its detractors as well. Among them, Rep. Marie Poulson (D):

“I am… the daughter of a rancher and a cattleman, but have another perspective on this. I realize the threat to cattle of these pests, or feral animals. But, in our particular case, we encourage the population of feral cats, as we have four granaries, and they were some of our best farm workers, and kept down the rodent population. My main problem with this bill is, there’s no designation between what’s considered a feral animal and your beloved house pet. And I think this bill gives license to kill in those areas. My other consideration here is that I have received so many letters from constituents upset by this bill that if I voted for it, I would be considered feral.”

Rep. David Litvack (D) wasn’t buying what Oda and his supporters were selling, especially when it comes to defining feral. “If a person knows that a particular animal is a pet of their neighbor,” explained Oda during his introductory comments, “it’s not feral. If it’s wearing a collar, it’s not feral. If there’s other signs it’s very friendly, obviously it’s not feral.”

Litvack was unmoved:

“I believe it is wrong for us, as a state, to move in the direction where we are having individuals make the decision, the determination on their own (1) what is feral, and (2) now, that they can shoot them, even if it’s only in an unincorporated county. Not a good policy, and, quite frankly, a bit of an embarrassment to the state of Utah.”

Referring specifically to Lines 153 and 154 of the amended bill (“…the humane shooting of an animal in an unincorporated area of a county, where hunting is not prohibited, if the person doing the shooting has a reasonable belief that the animal is a feral animal.”), Rep. Brian King (D) took a similar stance:

“My concern is that we’re providing a loophole in the statute for individuals that want to use this as an opportunity to go out and satisfy [lost audio] they get pleasure from going out and just shooting what are now defined as feral animals just for the pleasure of killing the animal… This is a bill that’s been brought to us now, in its amended form, just today, and we haven’t had a chance to hear from the Humane Society, from other individuals or agencies that have an interest in this. And my concern is that, although I think there is undoubtedly a reasonable need for individuals under certain circumstances—in rural areas, especially—to control feral animal populations that are causing damage, I still have concerns—without more input from those who deal with this, and have really had a chance to think the language through—in voting it out of our body.”

“We spent quite a bit of time reviewing with proposed amendments,” countered Cox. “We did have the opportunity of listening to a number of individuals speak for and on behalf of various options.”

Cox offered no specifics about who was invited to the bargaining table. And it may not have made any difference anyhow—like Oda and Perry, Cox seems to think HB 210 is about feral cat management:

“You have to decide whether or not it’s a good idea for individuals to purposely release certain animals—sometimes in large quantities into the wild that were not originally designed to be here. There are certain parts of the world that have had problems with this area, and in some cases, we have problems now. This provides us an option. We still have other options that are available—with trap, neuter, and release—those are still on the table. This does not prohibit those methods to be used, but does allow another method to be used.”

Rep. Paul Ray (R) responded to King’s concern by comparing TNR to abandonment (an argument perhaps first articulated by Jessup, who refers to TNR as “trap, neuter, and reabandon” [14]):

“It’s against the law to abandon an animal… [TNR practitioners] abandon the animal again. So when we’re talking about getting the perfect language, I’m not sure we can do that because even under the current law we have right now, we have some discrepancies…”

Setting aside the TNR/abandonment issue for the moment, that’s quite a position to take for somebody whose job it is to craft legislation: What we’ve got now isn’t perfect, so why bother?

Oda’s response was no better. “Out in the rural areas,” he said, referring to the concerns about the ambiguity surrounding the term feral, “they know exactly what animals belong in the area, so that’s not even an issue.”

This, I’m sure, was no consolation to Litvack or King.

Shoot First, Ask Questions Later
If you missed the part where the bill’s supporters defend—or even explain—the need for Utahns to be able to shoot feral animals, you’re not alone. I’ve listened to the entire debate at least twice now and still don’t get it.

As Laura Nirenberg, legislative analyst for Best Friends’ Focus on Felines campaign, pointed out to me, the bill’s language already addresses many issues brought up in the debate.

Under HB 210, for example, the crime of animal cruelty requires that “the person’s conduct is not reasonable and necessary to protect: (1) the actor or another person from injury or death; or (2) property from damage or loss if the property is an animal; or other property that is $50 or more in value.” (The $50 threshold seems like too low a bar to me, but it was never mentioned during the floor debate.)

This, it seems, goes an awful long way toward protecting farmers and ranchers who are merely protecting their livestock. And the Reese Ransoms of the world, too. Moreover, there’s already a provision in Utah’s animal cruelty code exempting a “person who humanely destroys any apparently abandoned animal found on the person’s property” (which, strangely, never came up during the HB 210 debate).

Granted, the bill’s amended language does lessen its potential impact on feral cats by restricting “the humane shooting of an animal” to unincorporated areas “where hunting is not prohibited.” Hunting regulations must comply with Utah criminal code, which prohibits the “discharge any kind of dangerous weapon or firearm… without written permission to discharge the dangerous weapon from the owner or person in charge of the property within 600 feet of: a house, dwelling, or any other building; or any structure in which a domestic animal is kept or fed, including a barn, poultry yard, corral, feeding pen, or stockyard.”

Even so, the shooting provision of HB 210 strikes me as essentially indefensible. It’s simply an invitation for senseless cruelty. Representative Litvack is exactly right: “Not a good policy, and, quite frankly, a bit of an embarrassment to the state of Utah.”

•     •     •

It will be interesting to see what happens when HB 210 moves to the Utah Senate, where, just last week, TNR-friendly SB 57 was passed. Among its provisions:

“This bill… defines a sponsor of a cat colony as a person who actively traps cats in a colony for the purpose of sterilizing, vaccinating, and ear-tipping before returning the cat to its original location; exempts community cats from the three-day mandatory hold requirement; and allows a shelter that receives a feral cat to release it to a sponsor that operates a cat program.”

I encourage readers to listen to the HB 210 debate in its entirety, as it provides a fascinating glimpse of democracy in action—warts and all (including, for example, when Oda responds to the call for a vote with “Meow.”) The SMIL audio file is available here, and the required Real Audio application can be downloaded free here.

Literature Cited
1. Coleman, J.S. and Temple, S.A., On the Prowl, in Wisconsin Natural Resources. 1996, Wisconsin Department of Natural Resources: Madison, WI. p. 4–8. http://dnr.wi.gov/wnrmag/html/stories/1996/dec96/cats.htm

2. Coleman, J.S. and Temple, S.A., How Many Birds Do Cats Kill?, in Wildlife Control Technology. 1995. p. 44. http://www.wctech.com/WCT/index99.htm

3. Mitchell, J.C. and Beck, R.A., “Free-Ranging Domestic Cat Predation on Native Vertebrates in Rural and Urban Virginia.” Virginia Journal of Science. 1992. 43(1B): p. 197–207. www.vacadsci.org/vjsArchives/v43/43-1B/43-197.pdf

4. USFWS, Migratory Bird Mortality. 2002, U.S. Fish and Wildlife Service: Arlington, VA. http://www.fws.gov/birds/mortality-fact-sheet.pdf

5.  USFWS, Perils Past and Present : Major Threats to Birds Over Time. 2003, U.S. Fish and Wildlife Service: Arlington, VA. http://www.fws.gov/birds/documents/PastandPresent.pdf

6. Gill, F.B., Ornithology. 3rd ed. 2007, New York: W.H. Freeman. xxvi, 758 p.

7. Pimentel, D., et al., “Environmental and Economic Costs of Nonindigenous Species in the United States.” Bio Science. 2000. 50(1): p. 53–65. http://www.bioone.org/doi/abs/10.1641/0006-3568%282000%29050%5B0053%3AEAECON%5D2.3.CO%3B2?journalCode=bisi

www.tcnj.edu/~bshelley/Teaching/PimentelEtal00CostExotics.pdf

8. Pimentel, D., Zuniga, R., and Morrison, D., “Update on the environmental and economic costs associated with alien-invasive species in the United States.” Ecological Economics. 2005. 52(3): p. 273–288. http://www.sciencedirect.com/science/article/B6VDY-4F4H9SX-3/2/149cde4f02744cae33d76c870a098fea

9. Hoagland, P. and Jin, D.I., “Science and Economics in the Management of an Invasive Species.”BioScience. 2006. 56(11): p. 931-935. http://www.mendeley.com/research/science-economics-management-invasive-species-8/

10. Clancy, E.A., Moore, A.S., and Bertone, E.R., “Evaluation of cat and owner characteristics and their relationships to outdoor access of owned cats.” Journal of the American Veterinary Medical Association. 2003. 222(11): p. 1541-1545. http://avmajournals.avma.org/doi/abs/10.2460/javma.2003.222.1541

11. Lord, L.K., “Attitudes toward and perceptions of free-roaming cats among individuals living in Ohio.” Journal of the American Veterinary Medical Association. 2008. 232(8): p. 1159-1167. http://www.avma.org/avmacollections/feral_cats/javma_232_8_1159.pdf

12. APPA, 2009–2010 APPA National Pet Owners Survey. 2009, American Pet Products Association: Greenwich, CT. http://www.americanpetproducts.org/pubs_survey.asp

13. Coleman, J.S., Temple, S.A., and Craven, S.R., Cats and Wildlife: A Conservation Dilemma. 1997, University of Wisconsin, Wildlife Extension. http://forestandwildlifeecology.wisc.edu/wl_extension/catfly3.htm

14. Jessup, D.A., “The welfare of feral cats and wildlife.” Journal of the American Veterinary Medical Association. 2004. 225(9): p. 1377-1383. http://www.ncbi.nlm.nih.gov/pubmed/15552312

http://www.avma.org/avmacollections/feral_cats/javma_225_9_1377.pdf

15. Winter, L., “Trap-neuter-release programs: the reality and the impacts.” Journal of the American Veterinary Medical Association. 2004. 225(9): p. 1369–1376. http://avmajournals.avma.org/doi/abs/10.2460/javma.2004.225.1369

http://www.avma.org/avmacollections/feral_cats/javma_225_9_1369.pdf

16. George, W., “Domestic cats as predators and factors in winter shortages of raptor prey.” The Wilson Bulletin. 1974. 86(4): p. 384–396. http://elibrary.unm.edu/sora/Wilson/v086n04/p0384-p0396.pdf

17. Miller, J. (2010, June 24). Charge questioned in death-of-kitten case. Standard-Examiner. http://www.standard.net/topics/courts/2010/06/23/charge-questioned-death-kitten-case

18. Gurrister, T. (2010, July 22, 2010). Cruelty charge in West Haven kitten case to be dismissed Standard-Examinerhttp://www.standard.net/topics/courts/2010/07/22/cruelty-charge-west-haven-kitten-case-be-dismissed

Best Available Science?

After a while, I suppose, such things will no longer surprise me.

A couple weeks ago, the American Bird Conservancy released a statement in support of the Florida Keys National Wildlife Refuges Complex Integrated Predator Management Plan/Draft Environmental Assessment proposed by the U.S. Fish and Wildlife Service (USFWS):

“American Bird Conservancy, the nation’s leading bird conservation organization, and 27 additional science and conservation organizations have signed a letter to the Florida Keys National Wildlife Refuge supporting their plans to remove cats and cat feeding stations found on refuge lands in the Keys because of the harm they are causing to birds and other wildlife, including endangered species.”

No surprise there, really. It’s the following paragraph that caught my eye:

“The U.S. Fish and Wildlife Service deserves credit for bringing the best available science to bear on the management of exotic predators inhabiting National Wildlife Refuge lands regardless of the emotional aspects of the issue,” said Steve Holmer, Senior Policy Advisor for American Bird Conservancy. “Given the overwhelming evidence of harm to native birds inhabiting and migrating through the Keys, this predator management plan offers hope for healthier environment.”

“Best available science”? Are we talking about the same document here?

Granted, this is Steve Holmer—the same guy who, a year ago, told the Los Angeles Times that there are 160 million feral cats in the U.S. (a figure he arrived at by “reinterpreting” the already inflated figure proposed by Dauphine and Cooper).

In other words, consider the source.

Among the letter’s highlights (the letter itself doesn’t seem to be available, which is a shame, as I’m very interested in knowing which other “science and conservation organizations” are supporters):

“…cat predation accounted for 50 percent and 77 percent of mortality of two endangered species—the Lower Keys Marsh Rabbit and the Key Largo Woodrat.”

Lower Keys Marsh Rabbit
ABC’s claim about cats being responsible for half the mortality of marsh rabbits doesn’t actually correspond with what’s in the USFWS plan:

“Free-roaming domestic cat predation accounted for 50 percent of adult Lower Keys marsh rabbit mortality during radio telemetry studies and was cited as the largest factor limiting their population viability in the 1990s (Forys and Humphrey 1999).” [1]

During her PhD dissertation work, Elizabeth Forys’ found that 13 of 24 rabbits monitored over the course of her research were killed by cats, [2] findings she described four years later (in the paper cited by USFWS) this way:

“Twenty-seven (18 M, 9 F) of the 43 radiocollared individuals died during our 2.5-year study. Domestic cats killed the most marsh rabbits (53 percent of all mortality), killing nearly an equal number of both juvenile and adult marsh rabbits.” [3]

ABC misrepresents both Forys’ work and the USFWS plan by transforming those 13 marsh rabbits into “50 percent of mortality of [this] endangered species.” And this is too straightforward to be an accident.

For what it’s worth, this has been done before.

Impact of Cats on Marsh Rabbits
The Multi-Species Recovery Plan (MSRP) for South Florida, published in 1999 by USFWS, refers repeatedly to Forys’ work, noting, for example:

“Although habitat loss is responsible for the original decline of the Lower Keys marsh rabbit, high mortality from cats may be the greatest current threat to the persistence of the Lower Keys marsh rabbit [4].”

The report’s authors alternate between concessions and allegations, the latter of which are based on what can only be considered—even in the most generous light—circumstantial evidence. They acknowledge, for instance, that “a detailed study of cat diets in the Keys has not been conducted,” but then point out that “rabbits were the largest component of feral cat diets in several studies that have been conducted elsewhere (Jones and Coman 1981, Liberg 1985).” [5]

Let’s set aside for the moment the debate about whether or not two is considered “several” (and the fact that they got the year wrong on the Liberg study). Where exactly were those studies conducted? “Victorian Mallee, Kinchega National Park in western New South Wales, and the Victorian eastern highlands” [6] and “Revinge area in southern Sweden.” [7]

None of which, it’s safe to say, could be mistaken for the Florida Keys.

USFWS also acknowledges that “the exact extent [of predation by cats] cannot be determined,” though they imply that it must be increasing: “the number of cats present in the Lower Keys has increased over the past 20 years with the increase in the residential population.” [5]

(In fact, a number of studies have shown that cats will shift their “preferences” according to prey availability [see, for example, the review in 8]. Indeed, this was the case in the study from southern Sweden cited by USFWS: “Wild rabbits were the most important prey, and cats responded functionally to changes in abundance and availability of this prey.” [7])

The less common the rabbits, the less likely they are to fall prey to free-roaming cats.

Telling Stories
Somewhere along the line, though, the marsh rabbit story began to change.

An article in The Key West Citizen describing USFWS’s 2007 effort to round up cats in the Keys [9, 10] is a clear reference to—and equally clear misrepresentation of—Forys’ work:

“According to a 1999 U.S. Fish and Wildlife report, feral cats have killed 53 percent of marsh rabbits in the Lower Keys.” [9]

Contributors to the 2008 South Florida Environmental Report claim, “feral cats… have contributed to a 50 percent decline in populations of Hugh Hefner’s rabbits (Sylvilagus palustris hefneri, an endangered subspecies of marsh rabbit named for Hefner’s contributions to their research) on Big Pine Key (CNN.com, accessed May 20, 2007).” [11] I was unable to find anything at the CNN site, but suspect the story was nothing more than a pick-up of the story that ran in The Key West Citizen. (Florida residents will no doubt take great comfort in knowing that the South Florida Water Management District, publisher of the report, is unwilling to look any further than CNN.com for its science.)

In the 2009 book Invasive Species: Detection, Impact and Control, the story is much the same:

“[cats] have been a factor in the 50 percent decline in populations of the endangered Lower Keys marsh rabbit (Forys and Humphrey 1999).” [12]

In fact, Forys and Humphrey have little to say about the declining population:

“During the 1970s and 1980s, a period of intense habitat destruction, a decline in marsh rabbits was reported (Lazell 1984).” [3]

And Lazell? Nothing at all about the marsh rabbit population. I did, however, find this interesting:

“In 1980 I live-trapped five specimens on Lower Sugarloaf Key under Florida Game and Fresh Water Fish Commission (FGFWFC) permit 28. Three were prepared as skins and skeletons; two were released after physiological studies (Dunson and Lazell, 1982).” [13]

Not that Lazell was the only scientist taking marsh rabbits. North of the Keys, 10 years earlier, Nicholas Holler and Clinton Conaway were studying the reproduction of this now-endangered species.

“From September 1968 through August 1969, 610 marsh rabbits were collected by hand or with a .22 caliber rifle in sugarcane plantations south and west of Belle Glade, Palm Beach and Hendry counties, Florida, at the southern edge of Lake Okeechobee. Rabbits were readily obtained except in July, August, and September…. After collection, rabbits were weighed and one eye and one front paw were preserved in 10 percent formalin.” [14]

To put this into perspective, the MSRP (published 30 years after Holler and Conway’s research) suggests that there may be only 100–300 marsh rabbits left. [5]

How’s that for irony? It seems the best evidence of a declining population comes from two scientists who killed several hundred marsh rabbits 40 years ago.

Key Largo Woodrat
ABC’s reference to Key Largo woodrat mortality is actually an accurate recounting of what’s in the USFWS plan:

“In addition, cats accounted for 77 percent of the mortality during a recent re-introduction of the Key Largo woodrat (S. Klett, Refuge Manager, personal communication).” [1]

Such personal communications—even by knowledgeable, honest professionals—are no substitute for rigorous, science-based reporting. What kind of sample size are we talking about? Over what duration? Under what conditions? Where? Etc.

More to the point, though: here is ABC once again blatantly misrepresenting the science (or the closest thing we’ve got to science, in this case). USFWS is talking about a portion of the population, while ABC is talking about the entire population. And I have to think the people responsible are smart enough to know the difference—which, of course, can mean only one thing: it’s not the intelligence that’s lacking here, but the integrity.

The Rest of the Best
But what about all the rest of the science—the “best available,” according to Holmer, don’t forget—that USFWS including in its Integrated Predator Management Plan/Draft Environmental Assessment? Among the more egregious errors and misinterpretations I cited in my comments to USFWS:

  • Another of the papers cited by USFWS has nothing to do with extinctions at all. As the authors describe it, their study was an evaluation of “whether a collar-worn pounce protector, the CatBib, reduces the number of vertebrates caught by pet cats and whether its effectiveness was influenced by colour or adding a bell.” [17]
  • Listed among the “evidence” of island extinctions were studies that—in addition to having nothing to do with extinctions—were not conducted on islands. Coleman and Temple’s 1993 survey, for example, involved rural Wisconsin residents and their outdoor cats, [18] while Churcher and Lawton surveyed residents of a small English village. [19]
  • Among the evidence that “free-roaming cats kill at least one billion birds every year in the U.S., representing one of the largest single sources of human-influenced mortality for small native wildlife,” [1] is Rich Stallcup’s 1991 article from the Observer, a publication of the Point Reyes Bird Observatory. In fact, “A Reversible Catastrophe” is little more than Stallcup’s advice—at once both folksy and sinister—about defending one’s garden from neighborhood cats (“…try a B-B or pellet gun. There is no need to kill or shoot toward the head, but a good sting on the rump seems memorable for most felines, and they seldom return for a third experience.” [21]).
  • Another of the studies cited by FWS—a 2008 paper by Sax and Gaines—isn’t about cats at all. Or even invasive animals. It’s about invasive plants. [22]
  • Citing the Centers for Disease Control and Prevention’s website, USFWS argues: “…free-roaming cats not only threaten wildlife through direct predation but also serve as vectors for a number of diseases including rabies, cat scratch fever, hookworms, roundworms and toxoplasmosis. Some of these diseases can be transmitted to other domestic animals, native wildlife, and in some cases, humans.”

    In fact, the CDC site makes no mention of cats being a threat to wildlife. And humans? “Although cats can carry diseases and pass them to people, you are not likely to get sick from touching or owning a cat.” And, notes the CDC, “People are probably more likely to get toxoplasmosis from gardening or eating raw meat than from having a pet cat.”

    (Unwilling to do their own research and writing, ABC uses exactly the same language and cites the same CDC website as USFWS. Had they simply clicked on the link, they might have avoided the blunder—which, I think, speaks volumes about little scrutiny they gave the USFWS plan before backing it.)

This is what Holmer is referring to when he says USFWS “deserves credit for bringing the best available science to bear on the management of exotic predators inhabiting National Wildlife Refuge lands regardless of the emotional aspects of the issue.”

What’s Missing
In addition to everything USFWS gets wrong, though, there’s also everything they overlooked or ignored (again, each point is covered in detail in my comments to USFWS). For example:

Mesopredator Release
“In the absence of large, dominant predators,” write Soulé et al., “smaller omnivores and predators undergo population explosions, sometimes becoming four to 10 times more abundant than normal.” [23] Several studies have demonstrated such an “explosion” of non-native rat populations as a result of cat populations being eliminated. [24–27]

As Courchamp et al. explain, “although counter-intuitive, eradication of introduced superpredators, such as feral domestic cats, is not always the best solution to protect endemic prey when introduced mesopredators, such as rats, are also present.” [26] Fan et al. warn of the risks involved with such eradication efforts: “In some cases, it may cause a disastrous impact to managed or natural ecosystems.” [25]

But USFWS doesn’t even mention the risk of mesopredator release, despite the fact that—should the population of free-roaming cats be sufficiently reduced—the situation in the Keys suggests that such an outcome is actually quite likely. And controlling these rats is complicated considerably by the need to protect Lower Keys marsh rabbits. Indeed, the MSRP warns of these rabbits coming into contact with pesticides and “poisons used to control black rats.” [5]

Based on evidence cited by USFWS itself, it’s clear that a dramatic reduction in the number of free-roaming cats in the Keys (assuming it’s possible—see below) will very likely have a negative impact on the marsh rabbit population—and may well lead to their extirpation from any Key where these rats are present.

Such impacts would also likely affect the Key Largo cotton mouse [28–29], Key Largo woodrat [30–31], and silver rice rat [32–33], all of which USFWS identifies as species of particular concern, and which are threatened—either through predation or competition—by non-native rats such as the black rat.

Removing Cats
Reports indicate that USFWS has a rather poor track record when it comes to trapping cats. Its 2003 contract with USDA, for example, yielded just 23 cats over 31 days of trapping. [34] Their efforts four years later—at a cost of $50,000—were equally ineffective. [9–10]

None of which should surprise USFWS. “Successful” eradication efforts require both extraordinary resources and profound cruelty. For example:

  • Nogales et al., describing the “success” of Marion Island, note, “it took about 15 years of intense effort to eradicate the cats, combining several methods such as trapping, hunting, poisoning, and disease introduction… The use of disease agents or targeted poisoning campaigns hold promise for an initial population reduction in eradication programs on large islands—such an approach may save effort, time, and money.” [35]
  • Cruz and Cruz point out that, of all the non-native mammals there, cats were “the most difficult to control or eliminate on Floreana Island.” Although “hunting with dogs was the single most effective method employed and it gave a sure body count,” the authors warn that “the method was costly and with the limited manpower available was only useful over small areas. Both poisoning and trapping were effective and the combination of the three methods is probably the most effective approach, as well as being the best use of time and materials.” [15]
  • Veitch describes efforts on 11-square-mile Little Barrier Island as “a determined [cat] eradication attempt” involving “cage traps, leg-hold traps, dogs and 1080 poison were used, but leg-hold traps and 1080 poison were the only effective methods.” [36] Four cats were also infected with Feline enteritis, but “because of the poor reaction to the virus no other cats were dosed and none were released… Altogether, 151 cats were known to have been killed before the eradication was declared complete. Important lessons learnt can be transferred to other feral cat eradication programmes.” [36] (By way of comparison, the Keys are approximately 137 square miles in total area.)

As USFWS admits, such methods are “not… socially acceptable” and “inconsistent with the points of consensus developed by the stakeholder group.” Yet, they offer nothing in the way of a feasible alternative; their latest plan is just more of what’s been done—and proven ineffective—in the past.

Because it’s extremely doubtful that USFWS will be able to remove the cats quickly enough to keep up with reproduction rates (again, consider the “success” stories outlined above), the most likely outcome of their plan is an increase in the number of feral cats in the Keys—and, of course, a corresponding increase in the negative impacts they have on the area’s wildlife and environment.

•     •     •

I fully expected ABC to support the USFWS plan. And, come to think of it, I should have expected them to blindly embrace the underlying science. After all, this is the same organization that’s been trying, since at least 1997, to sell the Wisconsin Study as valid research.

And, more recently, ABC endorsed “Feral Cats and Their Management” (also known as the University of Nebraska report) as if it were valid research.

Perhaps this is what ABC President and CEO George Fenwick meant when he wrote, in the preface to The American Bird Conservancy Guide to Bird Conservation, “every point of view has its own science.” [37]

Literature Cited
1. n.a., Draft Environmental Assessment: Florida Keys National Wildlife Refuges Complex Integrated Predator Management Plan. 2011, U.S. Fish & Wildlife Service: Big Pine Key, FL. http://www.fws.gov/nationalkeydeer/predatormgmt.html

http://www.fws.gov/nationalkeydeer/pdfs/USFWS%20FL%20Keys%20Refuges%20Integrated%20Predator%20Mgmt%20Plan%20&%20EA%20FINAL%20DRAFT.pdf

2. Forys, E.A., Metapopulations of marsh rabbits: A population viability analysis of the Lower Keys marsh rabbit (Sylvilagus palustris hefneri), in Department of Wildlife Ecology and Conservation. 1995, University of Florida: Gainesville. p. 244.

3. Forys, E.A. and Humphrey, S.R., “Use of Population Viability Analysis to Evaluate Management Options for the Endangered Lower Keys Marsh Rabbit.” The Journal of Wildlife Management. 1999. 63(1): p. 251–260. http://www.jstor.org/stable/3802507

4. Forys, E.A. and Humphrey, S.R., “Home Range and Movements of the Lower Keys Marsh Rabbit in a Highly Fragmented Habitat.” Journal of Mammalogy. 1996. 77(4): p. 1042-1048. http://www.jstor.org/stable/1382784

5. n.a., Multi-Species Recovery Plan for South Florida: Lower Keys Rabbit. 1999, U.S. Fish and Wildlife Service: Atlanta, GA. p. 151–171. http://www.fws.gov/verobeach/index.cfm?Method=programs&NavProgramCategoryID=3&programID=107&ProgramCategoryID=3

www.fws.gov/verobeach/images/pdflibrary/lkmr.pdf

6. Jones, E. and Coman, B.J., ” Ecology of the feral cat, Felis catus (L.), in southeastern Australia.” Australian Wildlife Research. 1981. 8: p. 537–547. http://www.publish.csiro.au/paper/WR9810537.htm

7. Liberg, O., “Food Habits and Prey Impact by Feral and House-Based Domestic Cats in a Rural Area in Southern Sweden.” Journal of Mammalogy. 1984. 65(3): p. 424-432. http://www.jstor.org/stable/1381089

8. Fitzgerald, B.M., Diet of domestic cats and their impact on prey populations, in The Domestic cat: The biology of its behaviour, D.C. Turner and P.P.G. Bateson, Editors. 1988, Cambridge University Press: Cambridge; New York. p. 123–147.

9. O’Hara, T. (2007, April 3). Fish & Wildlife Service to begin removing cats from Keys refuges. The Key West Citizen, from http://keysnews.com/archives

10. n.a., Lower Florida Keys National Wildlife Refuges Comprehensive Conservation Plan. 2009, U.S. Department of the Interior, Fish and Wildlife Service: Atlanta, GA. http://www.fws.gov/nationalkeydeer/

http://www.fws.gov/southeast/planning/PDFdocuments/Florida%20Keys%20FINAL/TheKeysFinalCCPFormatted.pdf

11. Ferriter, A., et al., The Status of Nonindigenous Species in the South Florida Environment, in 2008 South Florida Environmental Report. 2008, South Florida Water Management District.

12.  Engeman, R., Constantin, B., and Hardin, S., “Species Pollution” in Florida: A Cross Section of Invasive Vertebrate Issues and Management Responses, in Invasive Species: Detection, Impact and Control, C.P. Wilcox and R.B. Turpin, Editors. 2009. p. 179–197.

13. Lazell, J.D., Jr., “A New Marsh Rabbit (Sylvilagus palustris) from Florida’s Lower Keys.”Journal of Mammalogy. 1984. 65(1): p. 26–33. http://www.jstor.org/stable/1381196

14. Holler, N.R. and Clinton, H.C., “Reproduction of the Marsh Rabbit (Sylvilagus palustris) in South Florida.” Journal of Mammalogy. 1979. 60(4): p. 769–777. http://www.jstor.org/stable/1380192

15. Cruz, J.B. and Cruz, F., “Conservation of the dark-rumped petrel Pterodroma phaeopygia in the Galápagos Islands, Ecuador.” Biological Conservation. 1987. 42(4): p. 303-311. http://www.sciencedirect.com/science/article/B6V5X-48XKMBP-17J/2/f81b57e317f217802d9aca8b6927a88c

16. Kirkpatrick, R.D. and Rauzon, M.J., “Foods of Feral Cats Felis catus on Jarvis and Howland Islands, Central Pacific Ocean.” Biotropica. 1986. 18(1): p. 72-75. http://www.jstor.org/stable/2388365

17. Calver, M., et al., “Reducing the rate of predation on wildlife by pet cats: The efficacy and practicability of collar-mounted pounce protectors.” Biological Conservation. 2007. 137(3): p. 341-348. http://www.sciencedirect.com/science/article/B6V5X-4NGBB7H-3/2/456180347a2c3916d1ae99e220dd329e

18. Coleman, J.S. and Temple, S.A., “Rural Residents’ Free-Ranging Domestic Cats: A Survey.”Wildlife Society Bulletin. 1993. 21(4): p. 381–390. http://www.jstor.org/pss/3783408

19. Churcher, P.B. and Lawton, J.H., “Predation by domestic cats in an English village.” Journal of Zoology. 1987. 212(3): p. 439-455. http://dx.doi.org/10.1111/j.1469-7998.1987.tb02915.x

20. Hawkins, C.C., Impact of a subsidized exotic predator on native biota: Effect of house cats (Felis catus) on California birds and rodents. 1998, Texas A&M University.

21. Stallcup, R., “A reversible catastrophe.” Observer 91. 1991(Spring/Summer): p. 8–9. http://www.prbo.org/cms/print.php?mid=530

http://www.prbo.org/cms/docs/observer/focus/focus29cats1991.pdf

22. Sax, D.F. and Gaines, S.D., Species invasions and extinction: The future of native biodiversity on islands, in In the Light of Evolution II: Biodiversity and Extinction,. 2008: Irvine, CA. p. 11490–11497. www.pnas.org/content/105/suppl.1/11490.full

http://www.pnas.org/content/105/suppl.1/11490.full.pdf

23. Soulé, M.E., et al., “Reconstructed Dynamics of Rapid Extinctions of Chaparral-Requiring Birds in Urban Habitat Islands.” Conservation Biology. 1988. 2(1): p. 75–92. http://www.jstor.org/pss/2386274

http://deepblue.lib.umich.edu/bitstream/2027.42/74761/1/j.1523-1739.1988.tb00337.x.pdf

24. Fitzgerald, B.M., Karl, B.J., and Veitch, C.R., “The diet of feral cat (Felis catus) on Raoul Island, Kermadec group.” New Zealand Journal of Ecology. 1991. 15(2): p. 123–129. http://www.feral.org.au/the-diet-of-feral-cats-felis-catus-on-raoul-island-kermadec-group/

www.newzealandecology.org.nz/nzje/free_issues/NZJEcol15_2_123.pdf

25. Fan, M., Kuang, Y., and Feng, Z., “Cats protecting birds revisited.” Bulletin of Mathematical Biology. 2005. 67(5): p. 1081–1106. http://www.springerlink.com/content/p0h5854n56183874/

26. Courchamp, F., Langlais, M., and Sugihara, G., “Cats protecting birds: modelling the mesopredator release effect.” Journal of Animal Ecology. 1999. 68(2): p. 282–292. http://dx.doi.org/10.1046/j.1365-2656.1999.00285.x

http://deepeco.ucsd.edu/~george/publications/99_cats_protecting.pdf

27. Bergstrom, D.M., et al., “Indirect effects of invasive species removal devastate World Heritage Island.” Journal of Applied Ecology. 2009. 46(1): p. 73-81. http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2664.2008.01601.x/abstract

http://eprints.utas.edu.au/8384/4/JAppEcol_Bergstrom_etal_journal.pdf

28. n.a., Key Largo Cotton Mouse (Peromyscus gossypinus allapaticola) 5-Year Review: Summary and Evaluation. 2009, U.S. Fish and Wildlife Service, Southeast Region, South Fiorida Ecological Services Office: Veero Beach, FL. p. 19. http://ecos.fws.gov/speciesProfile/profile/speciesProfile.action?spcode=A086

http://ecos.fws.gov/docs/five_year_review/doc2378.pdf

29. n.a., Multi-Species Recovery Plan for South Florida: Key Largo Cotton Mouse. 1999, U.S. Fish and Wildlife Service: Atlanta, GA. p. 79–96. http://www.fws.gov/verobeach/index.cfm?Method=programs&NavProgramCategoryID=3&programID=107&ProgramCategoryID=3

http://www.fws.gov/verobeach/images/pdflibrary/klcm.pdf

30. n.a., Key Largo Woodrat (Neotomafloridana smalli) 5-Year Review: Summary and Evaluation. 2008, U.S. Fish and Wildlife Service, Southeast Region, South Fiorida Ecological Services Office: Vero Beach, FL. http://ecos.fws.gov/speciesProfile/profile/speciesProfile.action?spcode=A087

http://ecos.fws.gov/docs/five_year_review/doc1985.pdf

31. n.a., Multi-Species Recovery Plan for South Florida: Key Largo Woodrat. 1999, U.S. Fish and Wildlife Service: Atlanta, GA. p. 195–216. http://www.fws.gov/verobeach/index.cfm?Method=programs&NavProgramCategoryID=3&programID=107&ProgramCategoryID=3

http://www.fws.gov/verobeach/images/pdflibrary/klwr.pdf

32. n.a., Multi-Species Recovery Plan for South Florida: Rice Rat. 1999, U.S. Fish and Wildlife Service: Atlanta, GA. p. 173–194. http://www.fws.gov/verobeach/index.cfm?Method=programs&NavProgramCategoryID=3&programID=107&ProgramCategoryID=3

http://www.fws.gov/verobeach/images/pdflibrary/srra.pdf

33. n.a., Rice rat (Oryzomys palustris natator) 5-Year Review: Summary and Evaluation. 2008, U.S. Fish and Wildlife Service, Southeast Region, South Florida Ecological Services Office: Vero Beach, FL. http://ecos.fws.gov/speciesProfile/profile/speciesProfile.action?spcode=A083

http://ecos.fws.gov/docs/five_year_review/doc1958.pdf

34. n.a., Feral and Free-Ranging Cat Trapping by the USDA, APHIS, Wildlife Services (WS) on North Key Largo. 2004, U.S. Department of Agriculture.

35. Nogales, M., et al., “A Review of Feral Cat Eradication on Islands.” Conservation Biology. 2004. 18(2): p. 310–319. http://onlinelibrary.wiley.com/doi/10.1111/j.1523-1739.2004.00442.x/abstract

36. Veitch, C.R., “The eradication of feral cats (Felis catus) from Little Barrier Island, New Zealand.” New Zealand Journal of Zoology. 2001. 28: p. 1–12. http://www.royalsociety.org.nz/publications/journals/nzjz/2001/001/

http://www.royalsociety.org.nz/media/publications-journals-nzjz-2001-001.pdf

37. Lebbin, D.J., Parr, M.J., and Fenwick, G.H., The American Bird Conservancy Guide to Bird Conservation. 2010, London: University of Chicago Press.

Keys: To the Future

Below is a slightly reformatted version of the comments I submitted in response to the Florida Keys National Wildlife Refuges Complex Integrated Predator Management Plan/Draft Environmental Assessment. A PDF version is available here.

•     •     •

To Whom It May Concern:

I am writing to comment on the Florida Keys National Wildlife Refuges Complex Integrated Predator Management Plan/Draft Environmental Assessment. As I point out below, the IPMP/EA proposed by FWS fails to adequately address—or overlooks entirely—several key issues. Only now, for example—after years of struggling with this issue—does FWS propose to “imple­ment monitoring and conduct further research as needed to determine abundance and distribu­tion of free-roaming cats throughout the Refuge, document effectiveness of management actions taken or not taken on cat populations, and determine the impacts on the ecosystems and native species to aid in the adaptive management process.” [1]

How can FWS even put forward its IPMP/EA without this critical information in hand? One would expect, under the circumstances, that population estimates and scat analysis, for in­stance—along with whatever additional research might better inform any proposed action by FWS—would form the basis of such an IPMP/EA.

In addition, the IPMP/EA fails to address risks inherent with the improper management of free-roaming cats in the Keys. The plan proposed by FWS is unlikely to result in the removal of cats at a rate sufficient to keep pace with reproduction—a situation exacerbated greatly by its insistence on banning the feeding of feral cats and Trap-Neuter-Return (TNR) programs. Consequently, the population of feral cats may very well increase. And even if FWS is successful at removing cats from some locations, the IPMP/EA fails to take into account the risk of meso­predator release—the inevitable spike in non-native rodent populations—and its impact on the native species the IPMP/EA aims to protect.

For these reasons (each of which is outlined in detail below), I strongly encourage FWS to revise its IPMP/EA, especially as it pertains to the removal of feral cats.

Justification for Action
After a thorough reading of the Draft Environmental Assessment (EA) for the Florida Keys Na­tional Wildlife Refuges Complex (FKNWRC) Integrated Predator Management Plan—along with several supporting documents (as described below)—I am struck by how inadequately the IPMP/EA addresses several critical issues. Indeed, the Plan’s Justification for Management Action suggests that FWS has an insufficient and/or largely incorrect understanding of the impacts of feral and free-roaming cats on native wildlife and the environment.

Extinctions
Among the studies FWS cites to support its claim that “free-roaming cats have been shown to be a major cause of 33 native species extinction globally,” [1] is a 1987 paper by Cruz and Cruz, in which the authors, studying Galápagos Petrels, found that cats were hardly the only culprits:

“They are threatened by introduced rats, which attack eggs and young chicks… dogs and pigs which prey on eggs, nestlings and adults. Introduced goats, burros and cattle destroy nesting habitat and trample nests. A different combination of these pests and predators exists at each of the petrel nesting sites, while three of the islands are plagued by all of them.” [2]

The FWS would have the public believe the Galápagos Petrel is among those 33 extinctions. In fact, the birds are still there, though they are listed as Critically Endangered.

The story is similar for the 1986 paper by Kirkpatrick and Rauzon, another purported link between free-roaming cats and species extinctions. In fact, Kirkpatrick and Rauzon found that more than 90 percent of the diet of free-roaming cats on Jarvis Island and Howland Island was made up of Sooty Terns, Wedge-tailed Shearwaters, and Brown Noddies—each of which is listed as a species of Least Concern. [3]

Another of the papers cited by FWS has nothing to do with extinctions at all. As the authors describe it, their study was an evaluation of “whether a collar-worn pounce protector, the CatBib, reduces the number of vertebrates caught by pet cats and whether its effectiveness was influenced by colour or adding a bell.” [4]

Also listed among the “evidence” of island extinctions were studies that—in addition to having nothing to do with extinctions—were not conducted on islands. Coleman and Temple’s 1993 sur­vey, for example, involved rural Wisconsin residents and their outdoor cats, [5] while Churcher and Lawton surveyed residents of a small English village. [6]

Threatened or Endangered Species
FWS’s assertion that “many of the species impacted by free-roaming cats are federally listed threatened or endangered species and federally protected migratory birds” [1] is, while probably true, also largely meaningless. According to the 2009 State of the Birds report, published by the De­partment of the Interior:

“The United States is home to a tremendous diversity of native birds, with more than 800 species inhabiting terrestrial, coastal, and ocean habitats, including Hawaii. Among these species, 67 are federally listed as endangered or threatened. An additional 184 are species of conservation concern because of their small distribution, high threats, or declining popula­tions.” [7]

That translates to approximately 31 percent of all birds in this country being species of concern. FWS makes it sound as if perhaps the cats are targeting these birds; in fact, it’s obvious that all forms of mortality pose an acute threat to these vulnerable populations.

Disruptions to Native Ecosystems
When it comes to the disruption caused by cats to “the abundance, diversity, and integrity of na­tive ecosystems,” FWS turns to, among others, studies by Hawkins [8] and Jessup. [9]

But Hawkins’ dissertation work is plagued with problems that raise serious doubts about his rather triumphant conclusions—“the preference of ground feeding birds for the no-cat treatment was striking,” [8] for example. A closer look reveals that five of the nine ground-feeding birds in his study showed no preference for either area of the study site (a fact Hawkins downplays con­siderably). Without any explanation for why these vulnerable bird species were indifferent to the presence of an opportunistic predator, Hawkins is in no position to make the causal connections he does.

Jessup cites some well-known predation studies, but his concern is not the (presumed) impact on wildlife, per se, but rather the wholesale condemnation of “trap, neuter, and reabandon,” [9] as he calls it.

Birds and Cats
FWS claims that “free-roaming cats kill at least one billion birds every year in the U.S., repre­senting one of the largest single sources of human-influenced mortality for small native wildlife,” [1] supporting the assertion with just three sources, one of which is Rich Stallcup’s 1991 article from the Observer, a publication of the Point Reyes Bird Observatory. But “A Reversible Catastrophe” is very light on science—and, frankly, Stallcup gets most of that wrong. Mainly, the article is Stallcup’s manifesto regarding neighborhood cats:

“If you have a garden, why not proclaim it a wildlife sanctuary and protect it from non-native predators? If roaming cats come into your sanctuary to poach the wildlife under your steward­ship, you have the right and perhaps even the duty to discourage them in a serious way.” [10]

Stallcup goes on to suggest that gardeners “…try a B-B or pellet gun. There is no need to kill or shoot toward the head, but a good sting on the rump seems memorable for most felines, and they seldom return for a third experience.” [10]

Another of the studies cited by FWS—a 2008 paper by Sax and Gaines—isn’t about cats at all. Or even invasive animals. Although the authors do mention “the extinction of many native animal species on islands” [11] briefly in their introduction, the purpose of the paper is, as the authors state plainly enough, to “show that the number of naturalized plant species has increased linearly over time on many individual islands.” [11, emphasis mine]

Nevertheless, the assertion—made by FWS and many others, too—that “cats kill at least one billion birds every year in the U.S.” deserves careful scrutiny. Such aggregate figures can typically be traced to small—often flawed—studies, the results of which are subsequently extrapolated from one habitat to another, conflating island populations with those on continents, combining common and rare bird species, and so forth. Perhaps the most famous example of such pseudosci­entific manipulation is the infamous “Wisconsin Study” by Coleman and Temple.

Actually, there was no Wisconsin Study, in the scientific, peer-reviewed-publication sense. The often-cited “estimates”—which have, over the past 15 years, taken on mythical status—were nothing more than back-of-the envelopes guesses. Indeed, co-author Stanley Temple himself admitted that their figures weren’t “actual data,” though many—including the FWS—continue treating these figures as if they were actual data. “That was just our projection to show how bad it might be,” noted Temple. [12]

But Temple wasn’t as forthright about was the origin of their “estimates.” The authors’ “inter­mediate” figure of “38.7 million birds killed by rural cats” [13] is based on the results of a study involving just four “urban” cats and one rural cat in Virginia [14, 15] (this, in addition to Coleman and Temple’s several flawed assumptions). And their high estimate was even less valid.

Something else often left out of the debate: predation—even at high levels—does not automati­cally lead to population declines. In fact, some studies [16, 17] have shown that birds killed by cats are, on average, significantly less healthy than those killed through non-predatory events (e.g., collisions with buildings).

In the end, enormous “estimates” of annual predation rates are utterly meaningless—useful only as a sensational talking point by organizations interested in vilifying free-roaming cats. Such figures are routinely “sold” to a mainstream media and public unfamiliar with the larger context.

Threats to Public Health
Citing the Centers for Disease Control website, FWS argues:

“…free-roaming cats not only threaten wildlife through direct predation but also serve as vec­tors for a number of diseases including rabies, cat scratch fever, hookworms, roundworms and toxoplasmosis. Some of these diseases can be transmitted to other domestic animals, native wildlife, and in some cases, humans.” [1]

In fact, the CDC site makes no mention of cats being a threat to wildlife. And humans? “Al­though cats can carry diseases and pass them to people, you are not likely to get sick from touch­ing or owning a cat.” And, notes the CDC, “People are probably more likely to get toxoplasmosis from gardening or eating raw meat than from having a pet cat.”

There’s even a link to another page on the CDC’s site, called “Health Benefits of Pets.”

False Premises
The numerous misrepresentations, oversights, and errors outlined above suggest quite clearly that FWS either lacks a sufficient grasp of the critical issues involved—or that it’s not interested in being forthright with the public. This is not an academic issue; nor should my detailed criticism be considered nitpicking. After all, it’s quite clear that FWS intends to eliminate free-roaming cats on public—and, if possible, also private—land throughout the Keys. As “justification for ac­tion,” the IPMP/EA falls well short of what is required; as a public record, it is wholly unaccept­able—and, to be very candid about it—an embarrassment to the agency and the people involved. Simply put, any subsequent action taken by FWS on the basis of this IPMP/EA can, I think, rightfully be considered unjustified.

Moreover, in its attempt to focus on the impacts of cats, FWS overlooks some key factors. As a result, implementation of the IPMP/EA may very well increase the threat to the Keys’ native wildlife.

Mesopredator Release
In its IPMP/EA, FWS refers to two often-cited papers [18, 19] as evidence of cats disrupting native ecosystems, but fails to acknowledge the larger point made by the authors: the mesopreda­tor release phenomenon. “In the absence of large, dominant predators,” write Soulé et al., “smaller omnivores and predators undergo population explosions, sometimes becoming four to 10 times more abundant than normal.” [18]

For Soulé et al., coyotes were the dominant predators, while cats were the mesopredators. In other contexts, however, cats have been shown to play the dominant predator role with non-native rats becoming the mesopredators. [20–23].

Mathematical modeling of the mesopredator release phenomenon illustrates the complexities involved in eradication efforts, even on small islands. As Courchamp et al. explain, “although counter-intuitive, eradication of introduced superpredators, such as feral domestic cats, is not always the best solution to protect endemic prey when introduced mesopredators, such as rats, are also present.” [22] Fan et al. warn of the risks involved with such eradication efforts: “In some cases, it may cause a disastrous impact to managed or natural ecosystems.” [21]

Macquarie Island, located roughly halfway between New Zealand and Antarctica, offers a well-documented example of such a disastrous impact. In 2000, cats were eradicated from this United Nations Educational, Scientific and Cultural Organization World Heritage Site in order to protect its seabird populations. The resulting rebound in rabbit and rodent numbers, however, has had its own disastrous impact. “In response, Federal and State governments in Australia have committed AU$24 million for an integrated rabbit, rat and mouse eradication programme.” [23]

Mesopredator Release in the Keys
But FWS doesn’t even mention the risk of mesopredator release in its IPMP/EA, despite the fact that—should the population of free-roaming cats be sufficiently reduced—the situation in the Keys suggests that such an outcome is actually quite likely. (Because the population and diet of these cats is poorly understood in the Keys, the degree of reduction that would trigger a mesopredator release, too, is unknown.)

According to FWS, non-native rats are already “prevalent in residential and commercial areas.” [1] Should the removal of cats create a spike in their numbers, FWS suggests that they’re prepared to remove the rats, too: “Noticeable population increases based on reports, road kill, or other specific or auxiliary data may initiate targeted control and eradication efforts in addition to incidental capture…” [1]

But controlling these rats is complicated considerably by the need to protect Lower Keys marsh rabbits. The South Florida Multi-Species Recovery Plan (MSRP) warns of these rabbits coming into contact with pesticides and “poisons used to control black rats.” [24]

“In a 1993 Biological Opinion, the FWS investigated the effects of vertebrate control agents on endangered and threatened species and determined that several chemicals (e.g., Pival) would jeopardize the continued existence of the Lower Keys marsh rabbit. Chemicals—such as Pival—a rodenticide used to kill rats, are lethal if ingested. The FWS also concluded that if development in the Keys continues to increase, the potential for these animals to come in contact with such chemicals also increases, as does the potential for their extinction. Based on these findings, the FWS believes the continued use of such chemicals will result in the deaths of Lower Keys marsh rabbits. Given that the majority of occupied habitat is adjacent to urbanized areas, and that urbanization continues to expand into their habitat, then it can reasonably be predicted that the use of such chemicals has had a negative impact upon the Lower Keys marsh rabbit that may prevent its recovery.” [24]

Again, there’s no consideration whatsoever in the IPMP/EA for how the Lower Keys marsh rabbits—the protection of which was a key factor in the creation of the IPMP/EA in the first place—will be protected from increased predatory pressure by non-native rats. Yet, based on the evidence presented by FWS, it’s quite clear that the elimination of free-roaming cats in the Keys will very likely have a negative impact on their numbers—and may very well lead to the extirpation of marsh rabbits from any Key where these rats are present.

The same may be true of the Key Largo cotton mouse [25, 26], Key Largo woodrat [27, 28], and silver rice rat [29, 30], all of which are identified as species of particular concern in the IPMP/EA, and which are threatened—either through predation or competition—by non-native rats such as the black rat.

Alternatives
According to FWS, “the Proposed Action is a fully integrated range of nonlethal and lethal predator management strategies that would be available for implementation on the FKNWRC, depending on the status, distribution, and extent of predation by targeted predator species.” [1] Where feral cats are concerned, however, the “Proposed Action” is nothing more than the “tradi­tional” trap-and-kill approach—this, despite the fact that FWS lacks sufficient data concerning the distribution of, and extent of predation by, feral cats.

FWS is less than forthright on this point, however. According to the IPMP/EA:

“The Monroe County animal control service provider will have the authority to determine the final disposition of the trapped cats according to county ordinances and standards, which may include returning to owner, adopting out, relocating to a long-term cat care facility on the mainland, or euthanizing.” [1]

It’s no secret what happens to nearly every feral cat brought into shelters. As Nathan Winograd writes in his book Redemption: The Myth of Pet Overpopulation and the No Kill Revolution in America, “there is no other animal entering a shelter whose prospects are so grim and outcome so certain.” [31]

I asked Connie Christian, Executive Director of the Florida Keys SPCA about this last month. “Every cat brought to our facility is assessed to determine their disposition,” Christian told me via e-mail. “Every attempt is made to return ‘non-feral’ cats to their owners or place for adoption.”

“Unfortunately,” she continued, “we do not have an outlet for feral cats that are brought to us without a request for return.” Which would likely be the case for cats unlucky enough to be trapped by FWS.

(As I understand it, there was a no-kill shelter available at the time of the stakeholder meetings, thus buy-in from those concerned for the welfare of these cats. However, as this is no longer the case (again, this is my understanding of the situation), FWS cannot assume that the same level of buy-in exists today. And in any case, the suggestion of a no-kill shelter or sanctuary as a solution to the Keys’ feral cat issue is at best disingenuous.)

Removing Cats
Setting aside for the moment the issues mentioned above, the IPMP/EA offers little to suggest that FWS will actually be able to remove the free-roaming cats from the Keys. The fact that the agency has no idea how many cats there are is only the beginning. Reports indicate that FWS has a rather poor track record when it comes to trapping cats. Its 2003 contract with USDA, for example, yielded just 23 cats over 31 days of trapping. [32]

In 2007, FWS “received $50,000 to remove cats from federal refuges on Big Pine Key and Key Largo, and to protect endangered marsh rabbits, silver rice rats and other animals and birds that call the refuges home.” [33] Unofficial reports (I’m told nothing official has been issued yet) suggest that fewer than 20 cats were caught—some of which were clearly not feral—along with 81 raccoons, 53 of which were released alive. [34]

I think it’s safe to say that the Keys’ wildlife reaped little or no benefit from either effort. Had the 2007 funding been used for TNR, on the other hand, the impact could have been substantial.

Eradication Efforts
As I’m sure FWS is aware, numerous eradication efforts—the horrors of which are spelled out in some of the papers cited in the IPMP/EA—have been used to successfully remove cats from islands:

  • Nogales et al., describing the “success” of Marion Island, note, “it took about 15 years of intense effort to eradicate the cats, combining several methods such as trapping, hunting, poi­soning, and disease introduction… The use of disease agents or targeted poisoning campaigns hold promise for an initial population reduction in eradication programs on large islands—such an approach may save effort, time, and money.” [35]
  • Cruz and Cruz point out that, of all the non-native mammals there, cats were “the most dif­ficult to control or eliminate on Floreana Island.” Although “hunting with dogs was the single most effective method employed and it gave a sure body count,” the authors warn that “the method was costly and with the limited manpower available was only useful over small areas. Both poisoning and trapping were effective and the combination of the three methods is probably the most effective approach, as well as being the best use of time and materials.” [2]
  • Veitch describes efforts on 11-square-mile Little Barrier Island as “a determined [cat] eradi­cation attempt” involving “cage traps, leg-hold traps, dogs and 1080 poison were used, but leg-hold traps and 1080 poison were the only effective methods.” [35] Four cats were also infected with Feline enteritis, but “because of the poor reaction to the virus no other cats were dosed and none were released… Altogether, 151 cats were known to have been killed before the eradication was declared complete. Important lessons learnt can be transferred to other feral cat eradication programmes.” [36] (By way of comparison, the Keys are approximately 137 square miles in total area.)

As FWS notes in its IPMP/EA, such methods are “not… socially acceptable” and “inconsistent with the points of consensus developed by the stakeholder group.” While I agree completely that these methods are unacceptable, the “fully integrated range of nonlethal and lethal predator man­agement strategies” proposed by FWS strike me as nothing more than business as usual. How will this be any different (other than perhaps in terms of scale) than the failed efforts of the past?

If implemented as-planned, it seems clear that FWS will not be able to remove the cats quickly enough to keep up with reproduction rates. Using a population model, Andersen, Martin, and Roemer have suggested that, in the absence of a sterilization program, 50 percent of cats would have to be removed in order for a colony to decrease 10 percent annually. [37] This model has its flaws (some of which are described in “Reassessment”) but even if Andersen et al. are off by a factor of two, FWS would need to remove 25 per­cent of the free-roaming, unsterilized (and in the absence of TNR, it won’t be long before that’s the norm) cats continuously in order to achieve a modest 10 percent annual reduction in overall numbers.

Does anybody at FWS really think that’s going to happen? Where’s the evidence to suggest that it’s even possible?

If the feeding of feral cats and TNR are eliminated (to whatever extent possible) throughout the Keys, these cats will simply “go underground.” That means no more monitoring—and steriliz­ing—by the “foot soldiers” who currently care for them.

Indeed, it’s quite likely that feral cat complaint calls to Monroe County, FWS, and USDA would taper off considerably, as it becomes clear that such a call is essentially a death sentence. Thus, the cats would become that much more difficult to locate—and sterilize. The population, there­fore, would increase—probably very quickly.

In other words, the most likely outcome of the IPMP/EA put forward by FWS is an increase in the number of feral cats in the Keys—and, of course, a corresponding increase in the negative impacts they have on the area’s wildlife and environment.

Trap-Neuter-Return
In contrast to the IPMP/EA—with its risk of mesopredator release, on the one hand, and poten­tial to inadvertently drive up the numbers of feral cats, on the other—TNR offers the potential to more carefully manage the population of feral cats in the Keys. Indeed, given the precarious nature of wildlife in the Keys, TNR may actually be the best approach to fulfill the purpose of the IPMP/EA:

“…conserve and restore federally-listed species and protect all native fauna and flora on the [refuges] from population decline and potential extirpation or extinction due to predation by non-native species and human-subsidized populations of native predators.” [1]

The fact that TNR was “considered but dismissed from further evaluation,” again, suggests that FWS failed to adequately analyze all of the available predator management alternatives. And, similar to its “justification for action,” FWS’s rationale for dismissing TNR doesn’t hold up to scrutiny.

FWS argues, for example, that TNR “does little to reduce cat predation on native wildlife.” Al­though few predation studies have examined the hunting behavior of cats belonging to managed colonies, those that have are revealing. Reporting on their study of free-roaming cats in Brook­lyn, Calhoon and Haspel write: “Although birds and small rodents are plentiful in the study area, only once in more than 180 [hours] of observations did we observe predation.” [38]

And Castillo and Clarke (though highly critical of TNR) actually documented remarkably little predation in the two Florida parks they used for their study. In fact, over the course of approximately 300 hours of observation (this, in addition to “several months identifying, describing, and photographing each of the cats living in the colonies” [39] prior to beginning their research), Castillo and Clarke “saw cats kill a juvenile common yellowthroat and a blue jay. Cats also caught and ate green anoles, bark anoles, and brown anoles. In addition, we found the carcasses of a gray catbird and a juvenile opossum in the feeding area.” [39]

“In addition,” argues FWS, “the TNR method has little valid scientific support for claims that it actually reduces cat colony numbers over time and often has been shown to attract people to release new cats into an area.” [1] Ironically, some of the greatest TNR success stories are right there in the papers cited by FWS. Natoli, for example, reported a 16–32 percent decrease in population size over a 10-year period across 103 colonies in Rome—despite a 21 percent rate of “cat immigration.” [40] And, as of 2004, ORCAT, run by the Ocean Reef Community Associa­tion, had reduced its “overall population from approximately 2,000 cats to 500 cats.” [41] Accord­ing to the ORCAT website, the population today is approximately 350, of which only about 250 are free-roaming.

Any TNR program contends with the unfortunate (and illegal) dumping of cats. Still, it’s difficult to imagine that the presence or absence of a nearby TNR program would affect a person’s decision to abandon his/her pet cat(s). (If any studies had demonstrated such a connection, TNR opponents would surely cite them.) On the other hand, cats dumped near a managed colony are far more likely to be adopted and/or sterilized—thereby mitigating their potential impact on the overall population of unowned cats—as well any impacts to wildlife and the environment.

Moreover, FWS ignores the value of population stabilization. Julie Levy, Maddie’s Professor of Shelter Medicine in the University of Florida’s College of Veterinary Medicine, and one of the country’s foremost experts on feral cats, argues that “wildlife benefits when populations of cats that are trending rapidly upwards are at least stabilized.” [42] Nothing in the IPMP/EA suggests that such stabilization will be achieved in the Keys.

ESA and MBTA
Among the more perplexing aspects of FWS’s argument is their claim that “TNR practices are prohibited on National Wildlife Refuges, and violate the Endangered Species Act (ESA) and the Migratory Bird Treaty Act (MBTA) because they may result in the direct harm of protected species.”

This is an argument that’s been thrown around since at least 2003, when Pamela Jo Hatley, then a law student, suggested the possibility. But that’s all it was—and, apparently, is—a possibility.

“It is quite obvious that cats can be lethal to birds,” writes Hatley, “and if the death of a migratory bird can be traced to a cat, or a cat colony, which can be further traced to an individual or orga­nization, there may be strict liability for that person under the MBTA.” [43] Hatley’s argument for violations of the Endangered Species Act is similarly speculative: “…persons who release cats into the wild or who maintain feral cat colonies could be found liable for a take under section 9 of the ESA if maintenance of feral cats in the wild is found to kill or injure wildlife by degrading habitat.” [43]

It’s been nearly eight years now—a period during which TNR has undoubtedly increased substantially across the country—so where are all the court cases? If this were as black-and-white as FWS makes it sound, there wouldn’t even be a discussion about TNR (and the Urban Wildlands Group would likely have taken a very different tack in its opposition to TNR in Los Angeles).

Summary
There is no doubt that the Florida Keys are immensely valuable for their diversity of animal and plant life, some of which can be found nowhere else in the world. Due to a wide range of fac­tors—most of them human-caused—this habitat has become quite fragile, with some animal and plant species on the brink of extinction. Ecosystems—especially those as fragile as the Keys—are incomprehensibly complex, and tinkering with them is incredibly risky. And there’s plenty we simply do not know, and cannot—despite our best efforts—predict.

In its attempt to eliminate free-roaming cats from the Keys, FWS overlooks several important factors, thereby imposing a greater risk to the very native wildlife it aims to protect.

The IPMP/EA proposed by FWS fails to adequately address (1) the presumed impacts of free-roaming cats on native wildlife in the Keys, and (2) the risks inherent with the improper man­agement of these cats. It’s easy to imagine the losers in the deal—the cats, obviously, but also all of the wildlife FWS wants to protect. And the taxpayers, too, of course—this promises to be a dismal return on investment for all of us, no matter what our position might be on feral cats, wildlife conservation, and the like. The question is, where are the winners?

I strongly encourage FWS to revise its IPMP/EA, paying particular attention to these two issues, and to give further consideration to TNR in light of these and other important factors outlined in this letter.

Respectfully,

Peter J. Wolf
Independent Researcher/Analyst
www.VoxFelina.com

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33. O’Hara, T. (2007, April 3). Fish & Wildlife Service to begin removing cats from Keys refuges. The Key West Citizen, from http://keysnews.com/archives

34. n.a., Lower Florida Keys National Wildlife Refuges Comprehensive Conservation Plan. 2009, U.S. Department of the Interior, Fish and Wildlife Service: Atlanta, GA. http://www.fws.gov/nationalkeydeer/

http://www.fws.gov/southeast/planning/PDFdocuments/Florida%20Keys%20FINAL/TheKeysFinalCCPFormatted.pdf

35. Nogales, M., et al., “A Review of Feral Cat Eradication on Islands.” Conservation Biology. 2004. 18(2): p. 310–319. http://onlinelibrary.wiley.com/doi/10.1111/j.1523-1739.2004.00442.x/abstract

36. Veitch, C.R., “The eradication of feral cats (Felis catus) from Little Barrier Island, New Zealand.”New Zealand Journal of Zoology. 2001. 28: p. 1–12. http://www.royalsociety.org.nz/publications/journals/nzjz/2001/001/

http://www.royalsociety.org.nz/media/publications-journals-nzjz-2001-001.pdf

37. Andersen, M.C., Martin, B.J., and Roemer, G.W., “Use of matrix population models to estimate the efficacy of euthanasia versus trap-neuter-return for management of free-roaming cats.” Journal of the American Veterinary Medical Association. 2004. 225(12): p. 1871–1876. http://www.avma.org/avmacollections/feral_cats/default.asp

http://www.avma.org/avmacollections/feral_cats/javma_225_12_1871.pdf

38. Calhoon, R.E. and Haspel, C., “Urban Cat Populations Compared by Season, Subhabitat and Supplemental Feeding.” Journal of Animal Ecology. 1989. 58(1): p. 321–328. http://www.jstor.org/pss/5003

39. Castillo, D. and Clarke, A.L., “Trap/Neuter/Release Methods Ineffective in Controlling Domestic Cat “Colonies” on Public Lands.” Natural Areas Journal. 2003. 23: p. 247–253.

40. Natoli, E., et al., “Management of feral domestic cats in the urban environment of Rome (Italy).”Preventive Veterinary Medicine. 2006. 77(3-4): p. 180-185. http://www.sciencedirect.com/science/article/B6TBK-4M33VSW-1/2/0abfc80f245ab50e602f93060f88e6f9

www.kiccc.org.au/pics/FeralCatsRome2006.pdf

41. Levy, J.K. and Crawford, P.C., “Humane strategies for controlling feral cat populations.” Journal of the American Veterinary Medical Association. 2004. 225(9): p. 1354–1360. http://www.avma.org/avmacollections/feral_cats/default.asp

http://www.avma.org/avmacollections/feral_cats/javma_225_9_1354.pdf

42. Levy, J.K., Personal communication, 2010.

43. Hatley, P.J., Feral Cat Colonies in Florida: The Fur and the Feathers Are Flying. 2003, University of Florida Conservation Clinic: Gainsville, FL. http://www.animallaw.info/articles/arus18jlanduseenvtll441.htm

www.law.ufl.edu/conservation/pdf/feralcat.pdf

Politics, Religion, and Witch Hunts

I don’t mean to take anything away from Stephen Colbert and Jon Stewart, but it sometimes seems as if our politicians craft legislation with the sole intent of scoring priceless airtime on the The Colbert Report or The Daily Show. Little wonder these shows are both incredibly popular and enduring: the material just keeps coming.

And, really, you can’t make this stuff up.

Last week, Colbert took Utah Representative (and Buddhist) Curtis Oda (R) to task for his sponsorship of HB 210, which “amends provisions of the Utah Criminal Code relating to animal cruelty and animal torture,” including allowances for “the humane shooting or killing of an animal if the person doing the shooting or killing has a reasonable belief that the animal is a feral animal.”

As for what constitutes “humane” or “reasonable,” that’s anybody’s guess—plenty of grist for Colbert’s mill…

The Colbert Report Mon – Thurs 11:30pm / 10:30c
Mr. Smith Goes to the State Legislature Then Later Possibly Washington – Curtis Oda
www.colbertnation.com

Colbert Report Full Episodes Political Humor & Satire Blog Video Archive

The fact that Colbert got such mileage out of HB 210 is no surprise—that’s what he does, after all. And HB 210 is so absurd to begin with, his satirical rant required only a slight stretch.

The question is: how does such legislation getting any traction at all?

Postscript
According to a guest editorial in Utah’s Daily Herald newspaper, the answer for some is “human dominion within the Christian tradition.” (The same topic that Stephen Vantassel, of “Feral Cats and Their Management” fame, tackled in his PhD dissertation, dedicated, by the way, to “fur trappers who, every winter, brave the harsh weather in continuance of America’s oldest industry. Regrettably, they must also endure the ravages of urban sprawl and the derision of an ungrateful and ignorant public.” As I say, you really can’t make this stuff up.)

I’ll leave it to others (Stephen Colbert, are you listening?) to poke holes in the theological rationale put forth by Dr. Clayton M. White, professor emeritus at Brigham Young University, and his nameless co-author—but can’t help weighing in on their science:

“In Wisconsin alone, where data are good, about 39 million native animals are killed annually by pet and feral cats.”

That’s right: despite their combined “90 years of work in zoology and conservation,” these two are trying to sell the Wisconsin Study’s estimates as actual data (and, by association, the Wisconsin Study as an actual study).

Talk about unshakable faith!

Note: You can sign the Change.org petition opposing HB 210 here.

Revisiting “Reassessment”

“Reassessment: A Closer Look at ‘Critical Assessment of Claims Regarding Management of Feral Cats by Trap-Neuter-Return’” has been revised and expanded!

Image of "Reassessment" Document

This paper, a brief review and critique of the essay “Critical Assessment of Claims Regarding Management of Feral Cats by Trap-Neuter-Return” by Travis Longcore, Catherine Rich, and Lauren M. Sullivan, now includes sections on Toxoplasma gondii, the mesopredator release phenomenon, and more. In addition, links and downloadable PDFs have been added to the list of references.

Over the past year, “Critical Assessment” has gotten a great deal of traction among TNR opponents, despite its glaring omissions, blatant misrepresenta­tions, and obvious bias. “Reassessment”—intended to be a resource for a broad audience, including, wildlife and animal control professionals, policymakers, and the general public—shines a bright spotlight on these shortcomings, thereby bringing the key issues back into focus.

Act Locally
Politics is, as they say, local. This is certainly true of the debate surrounding TNR. Policies endorsing TNR, the feeding of feral cats, etc. typically begin with “Town Hall” meetings, or even meetings of neighborhood associations. “Reassessment” provides interested parties with a rigorous, science-based counter-argument to those using “Critical Assessment” as a weapon against feral cats/TNR.

So, once you’ve had a look for yourself, please share generously! Together, we can—in keeping with the mission of Vox Felina—improve the lives of feral cats through a more informed, conscientious discussion of feral cat issues in general, and TNR in particular.

Download PDF

American Bird Con

For years now, the American Bird Conservancy (ABC) has been promoting erroneous and misleading information in their tireless effort to vilify free-roaming cats. No organization has been more effective at working the anti-TNR pseudoscience into a message neatly packaged for the mainstream media, and eventual consumption by the general public. Speaking to the Wall Street Journal in 2002, Becky Robinson, co-founder and President of Alley Cat Allies, described ABC’s Cats Indoors! campaign as “a new environmental witch hunt.” [1]

Book Cover: The American Bird Conservancy Guide to Bird Conservation

In their recently released book, The American Bird Conservancy Guide to Bird Conservation, ABC changes tack a bit—using what the authors call “conservative” estimates of the outdoor cat population and annual predation rates, for example, to arrive at their figure of “532 million birds killed annually by outdoor cats.” [2] At the same time, they include much of the same misinformation ABC’s been promoting all along. It’s a clever strategy, really: endorsing bogus claims as valid science without having to defend them as such.

In fact, one doesn’t need to get past the book’s preface before realizing the role that science plays—or, more to the point, doesn’t play—at ABC. “We see very few issues resolved through coming to consensus on the science,” writes President and CEO George Fenwick.

“More often, science divides us. So, though we continue to need excellent science, conservationists also need to learn how to better persuade, use media effectively, and connect birds to the human condition, spirituality and ethical values.” [2]

If its section on cats is any indication, The ABC Guide is the manifestation of Fenwick’s philosophy: more style than substance, more sales than science. The authors didn’t even bother with citations and references, suggesting to readers, perhaps, that The ABC Guide is the last word on the subject. Where free-roaming cats are concerned, though, ABC has precious few answers—in part because they (still) aren’t asking the right questions.

Outdoor Cats
Referring to unattributed 2007 data, the authors of The ABC Guide—Daniel Lebbin, Michael Parr, and George Fenwick—claim that 43 percent of pet cats “have access to the outdoors.” [2] But, according to American Pet Products Association (APPA) 2008 National Pet Owners Survey, 64 percent of cats are indoor-only during the daytime, and 69 percent are kept in at night [3].

Other surveys have yielded similar results, and also indicate that, of those cats that are allowed outdoors, approximately half were outside for three hours or less each day [4, 5]. For Lebbin et al., though, these part-timers are no different from their feral relatives. Of which, “there are 60–120 million,” according to the authors. [2]

Where this figure comes from is anybody’s guess. It’s substantially higher than any other estimates I’ve seen, with one notable exception—a statement made earlier this year by an ABC official (more on that in a moment).

Feral Cat Numbers
Very little exists in terms of credible population estimates for feral cats. There are, however, many unsubstantiated claims.

Among the most popular for those interested in big numbers is the first line from David Jessup’s ironically titled 2004 paper “The welfare of feral cats and wildlife” (ironic because his “concerns” for the welfare of these cats are so plainly disingenuous): “There are an estimated 60 to 100 million feral and abandoned cats in the United States.” [6] As to the origins of Jessup’s “estimate,” again, it’s anybody’s guess, as he offers no reference.

Based on the results of a 1999 telephone survey of Alachua County, Florida, residents, Levy et al. estimated that the population of free-roaming cats represented approximately 44 percent of the county’s total population of cats. [7] Other researchers have reported similar figures for nationwide estimates. [8] By way of comparison, ABC’s estimate represents 39–56 percent of the overall population of cats in the U.S. (based on APPA’s latest figures for pet cats).

On the other hand, Merritt Clifton of Animal People, an independent newspaper dedicated to animal protection issues, makes a compelling argument that the population of feral cats in the U.S. is much smaller than is often reported, and may very well be on the decline. [9] Clifton’s estimates are derived not from surveys of homeowners feeding stray and feral cats, but from “information about the typical numbers of cats found in common habitat types, gleaned from a national survey of cat rescuers… cross-compared with animal shelter intake data.” [10] In 2003, Clifton suggested that “the winter feral cat population may now be as low as 13 million and the summer peak is probably no more than 24 million.” [10]

Population Increase
Earlier this year, ABC’s Senior Policy Advisor, Steve Holmer, told the Los Angeles Times, “The latest estimates are that there are about . . . 160 million feral cats [nationwide].” When pressed for details, Holmer referred me to Nico Dauphine and Robert Cooper’s 2009 Partners In Flight Conference paper. Which, as it turns out, leads right back to ABC and their Cats Indoors! campaign.

Dauphine and Cooper begin their adventure in creative accounting with Jessup’s unattributed 100 million, and add to it the number of owned cats they describe as “free-ranging outdoor cats for at least some portion of the day.” [11] For which they turn to Linda Winter, former director of Cats Indoors!, and her 2004 paper in which she reports the findings of a 1997 telephone survey (commissioned by ABC) of cat owners. According to Winter, “66 percent of cat owners let their cats outdoors some or all of the time.” [12]

In fact, the survey—as reported in ABC’s brochure “Human Attitudes and Behavior Regarding Cats”—indicated that “35 percent keep their cats indoors all of the time” and “31 percent keep them indoors mostly with some outside access.” [9] The difference in wording is subtle and hampered by imprecision (it all comes down to the meaning of some), but it’s difficult not to see this as deliberately misleading on Winter’s part.

In any case, results of other surveys (described previously) suggest quite convincingly that outdoor access for the vast majority of pet cats is really very limited. Nevertheless, Dauphine and Cooper persist, arriving at a staggering “117–157 million free-ranging cats.” [11] Holmer, in turn, rounds off the upper limit, “scrubs” the pet cats from the calculation by calling them all ferals, and gets the bogus figure printed in the Times. (Gold star for Holmer!)

Lebbin et al. don’t go that far, but their “most conservative estimate of outdoor and feral cats in the U.S.”—95 million—is, given its shaky origins, no more valid than Dauphine and Cooper’s.

Predation
According to The ABC Guide, “all outdoor cats hunt and kill birds (20­–30 percent of cat prey) and other small animals.” [2] No study I’m aware of has demonstrated that all cats hunt. On the contrary, some research suggests that less than half of outdoor cats hunt. Figures as low as 36–56 percent have been reported by researchers in Australia, for example. [13]

In the UK, Baker, Bentley, Ansell, and Harris reported that 77 cats returned a total of 212 prey items to 52 Bristol households participating in their pilot study, but “in each sampling period, the majority of cats (51–74 percent) failed to return any prey.” [14] The subsequent 12-month study (this time involving 186 Bristol households, 275 cats, and 495 prey items) found a similar level of apparent non-hunters: roughly 61 percent. [15]

Woods, McDonald, and Harris, also working in the UK, found that, although 91 percent of cats returned at least one item, “approximately 20–30 percent of cats brought home either no birds or no mammals.” [16] And Churcher and Lawton’s yearlong “English Village” study (involving approximately 70 cats and 1,090 documented prey items) found that that 8.6 percent of cats brought home no prey [17] (though the authors don’t specify the percentage of cats that returned no birds).

And while it’s true that cats are unlikely to return home with all they prey they catch, it’s equally true that they will bring home items they didn’t kill. Very little is known about the extent of either phenomenon, however. (Carol Fiore’s [18] attempt to unravel this mystery is plagued by methodological missteps and obvious bias; William George’s [19] comments are often interpreted as suggesting that cats return only half of what they catch, though this is incorrect.)

The Diet of Cats
The idea that birds make up 20–30 percent of the diet of free-roaming cats is one that ABC has been promoting since 1997, when they launched Cats Indoors! But it’s no more valid now than it was then.

According to ABC’s brochure, “Domestic Cat Predation on Birds and Other Wildlife” (downloadable from their website), “extensive studies of the feeding habits of domestic, free-roaming cats… show that approximately… 20 to 30 percent [of their diet] are birds.” Ellen Perry Berkeley carefully examined—and debunked—this claim in her book, TNR Past Present and Future: A history of the trap-neuter-return movement, noting that ABC’s 20–30 percent figure wasn’t based on “extensive studies” at all. [10]

In fact, just three sources were used: the now-classic “English Village” study by Churcher and Lawton [11], the infamous “Wisconsin Study,” and researchers Mike Fitzgerald and Dennis Turner’s contribution to The Domestic Cat: The Biology of Its Behaviour. [12]

As Berkeley points out, combining or comparing data from these three sources is entirely inappropriate. Both the English Village and Wisconsin studies report the percentage of birds returned as a portion of the “total catch,” whereas Fitzgerald reports percentage by frequency (i.e., the occurrence of birds in the stomach contents or scats of free-roaming cats).

To put this into more familiar terms, consider coffee consumption. According to the 2009 National Coffee Drinking Trends Study, 54 percent of American adults drink coffee daily—54, then, is the percentage by frequency. To say that coffee makes up 54 percent of our dietary intake—essentially ABC’s interpretation—is obviously a gross exaggeration of consumption levels. (Neither measure says anything about the supply of coffee, of course.)

Nevertheless, 13 years after ABC first published its report—and six years after Berkeley exposed the error publicly in TNR—the myth persists. So much for ABC’s commitment, spelled out in the book’s section on threats, to “address all of the major threats responsible for killing large numbers of birds, using the best information and research available, while promoting further research and monitoring where it is most needed.” [2]

Which, in turn, raises serious questions about the integrity of ABC and the people running it.

Declawed Cats
Citing Fiore’s thesis research, Lebbin at al. conclude, “de-clawed cats kill as many birds as cats with claws.” [2] Fiore herself is equally confident:

“There were seven declawed cats in the study and all but one took birds (giving a figure of 86 percent); the top predator cat was declawed. Declawing cats appears to have no effect whatsoever on the ability to hunt birds.” [18]

But, both ABC and Fiore leave out some critical details. There were, after all, only 41 cats involved in the study—hardly the kind of sampling required to make such sweeping statements.

A closer look reveals that the declawed cats were apparently responsible for killing an average of 3.6 birds/cat/year while the cats with claws had an average of 3.0. Does this mean that the declawed cats are actually superior hunters compared to the other cats? Hardly.

In addition to the sampling issue, there’s the problem inherent in using the average to describe highly skewed distributions (many cats catching few prey, while few cats catch many prey). In such instances, it’s more appropriate to use median values, which better represent “average” hunting success. [20] Doing so yields estimates of 1 bird/cat/year for the declawed cats vs. 2 birds/cat/year for the cats with claws.

So, declawed cats kill only half as many birds as those with claws? I’ll leave such indefensible claims to others.

Now, to be clear: I’m no advocate of declawing. Nor do I think it’s in the best interest of pet cats to be outdoors—especially those without claws. My point here is merely to demonstrate the flaws in ABC’s deceptively straightforward assertion; once again, ABC is more interested in a good story than they are in good science. (Their comment about declawed cats is precisely the kind of sound-bite that is easily picked up by the media, and repeated so widely that it becomes nearly impossible to trace—never mind untangle.)

Cats and Birds
As evidence of the “variable predation rates by cats,” [2] The ABC Guide refers to just four studies. And, although no citations are included, people familiar with the literature will recognize the numbers and locations immediately.

  1. From Christopher Lepczyk’s dissertation work, the authors somehow extract a figure of 35.5 birds/cat/year, near the low end of Lepczyk’s own estimate of “between 0.7 and 1.4 birds per week.” [21] But Lepczyk’s research suffers from a range of problems—both in terms of his methods and analysis—that inflate his estimated predation rates. (Interestingly, ABC’s Fenwick and Winter are among those Lepczyk thanks “for helpful and constructive reviews” in the Acknowledgements section.)
  2. Another of the predation rates included in The ABC Guide is the more moderate 15 birds/cat/year from Crooks and Soulé’s 1999 paper [22]. But here, too, there are flaws that lead to bloated predation levels.Like Lepczyk, Crooks and Soulé asked residents to estimate annual levels of prey returned home by their cats (in contrast to some studies in which actual prey items are recorded and/or collected). But such guesswork becomes less accurate as estimates increase. David Barratt found that “predicted rates of predation greater than about ten prey per year generally over-estimated predation observed” [20]. At the levels reported by Crooks and Soulé—an average of 56 total prey items (including birds, mammals, etc.) per year—predicted rates were often twice actual predation rates.

    Also, Crooks and Soulé seem (not enough detail is provided in their paper to be certain) to have used a simple average in their calculations, perhaps doubling true predation levels. Taken together, these factors suggest that actual predation levels might be just a quarter of those suggested by Crooks and Soulé.

  3. The third study—easily the most rigorous of the four—with a predation rate of 9.6 birds/cat/year, comes from Woods et al. The researchers, having recruited study participants solely from The Mammal Society, allow that they “may have focused on predatory cats,” and ask that their results be “treated with requisite caution.” [16] They also make clear that their estimated predation rates “do not equate to an assessment of the impact of cats on wildlife populations” [16] (more on that shortly)
  4. Finally, there is the—seemingly inevitable—reference to the Wisconsin Study, though for some reason (again, without explanation) Lebbin et al. have adjusted Coleman and Temple’s figures of 28–365 birds/cat/year downward: “between 5.6 and 109.5.” [2]In this case, the details hardly matter. The Wisconsin Study isn’t actually a study at all; no predation data or findings were ever published. Coleman and Temple’s “estimates”—widely circulated as valid research, thanks in part to ABC—were nothing more than back-of-the-envelope calculations. “Our best guesses,” as the authors themselves admit, “at low, intermediate and high estimates of the number of birds killed annually by rural cats in Wisconsin.” [23]

    “Those figures were from our proposal,” Temple told The Sonoma County Independent. “They aren’t actual data; that was just our projection to show how bad it might be.” [24]

    Sixteen years later, though, ABC is still trying to make “actual data” out of “not actual data.” (Granted, they have backed off from Coleman and Temple’s high estimate, but no mathematical adjustments can transform these flawed, biased guesses into valid research findings.)

Cats as Hunters
Contrary to popular myth, evidence suggests that cats are not quite the hunters they’ve been made out to be. Fitzgerald and Turner suggest that the hunting behavior of cats leads to many “failures,” and, as a result, “many cats soon give up bird hunting altogether.” [25]

“Primarily, all cats hunt both birds and rodents with equal zeal,” observed German zoologist Paul Leyhausen, “and many obviously prefer eating birds.” But, argues Leyhausen (1916–1998), who spent the bulk of his career studying the behavior of cats, “they cannot catch them as easily, and for this reason with increasing experience may soon give up hunting birds.” [26]

“However, our town cats today are often compelled, because of the almost total absence of rodents in their territory to concentrate on chasing birds in order to discharge their pent-up hunting propensities. Even in these circumstances, however, cats are not capable of seriously endangering the songbird population of a substantial area. They almost always catch only old, sick or young specimens. But three quarters of the young birds must perish anyway, since the size of the population in an area remains fairly constant on an average over the years… During years in the field I have observed countless times how cats have caught a mouse or a rat and just as often how they have stalked a bird. But I never saw them catch a healthy songbird that was capable of flying. Certainly it does happen, but, as I have said, seldom. I should feel sorry for the average domestic cat that had to live solely on catching birds.” [26]

Although few predation studies have examined the hunting behavior of cats belonging to managed colonies, those that have are revealing. Reporting on their study of free-roaming cats in Brooklyn, Calhoon and Haspel write: “Although birds and small rodents are plentiful in the study area, only once in more than 180 [hours] of observations did we observe predation.” [27]

Castillo and Clarke, though highly critical of TNR (“This method is not an effective means to control the population of unwanted cats and confirms that the establishment of cat colonies on public lands encourages illegal dumping and creates an attractive nuisance.” [28]), documented little predation in the two Florida parks they used for their study (the focus of which was TNR efficacy, not predation). Over the course of approximately 300 hours of observation (this, in addition to “several months identifying, describing, and photographing each of the cats living in the colonies” [28] prior to beginning their research), Castillo and Clarke “saw cats kill a juvenile common yellowthroat and a blue jay.” [28]

“Cats also caught and ate green anoles, bark anoles, and brown anoles. In addition, we found the carcasses of a gray catbird and a juvenile opossum in the feeding area.” [28]

Another study conducted in a public park, this one in Alameda County, California, also reported low levels of apparent predation of birds (though researcher Cole Hawkins makes every attempt to suggest otherwise). Of 120 scat samples found by searching the “cat area” of Hawkins’ study site, “65 percent were found to contain rodent hair and 4 percent feathers.” [2] This finding comes toward the end of the study, when the cat population was at its greatest (22 were sighted)—and still, only 4 percent contained feathers. And this could easily represent one cat and one bird (and, strictly speaking, even this is not evidence of actual predation, as the bird(s) could have been scavenged).

Impact
To arrive at their figure of “532 million birds killed annually by outdoor cats,” Lebbin et al. multiply “the most conservative predation rate (5.6 birds per cats per year) by the most conservative estimate of outdoor and feral cats in the U.S. (95 million).” [2] They go on to suggest that “the actual number” is “likely… much higher,” [2] though, of course, they ignore or overlook all the errors and misrepresentations bound up in their basic calculation.

Even setting all that aside, the question remains: What impact does predation by cats have on bird populations?

Islands and Continents
Here, the authors focus mostly on the extinction of seabirds linked to the presence of feral cats on islands. I’m only vaguely familiar with the examples they cite, but if the case of the Stephens Island Wren is any indication, the stories are far more complex than ABC suggests. [see, for example, 29 and 30]

But, as Fitzgerald and Turner point out, “because the range of prey available on islands differs markedly from that on the continents the two groups, continents and islands, are treated separately.” [25]

And when it comes to the impact of cats on continental bird populations, ABC highlights rare and endangered species—but ignores entirely two key points. First, as was mentioned previously, even high rates of predation do not equate to population declines.

Referring to the estimated 30 percent of House Sparrow mortality attributed to cat predation in the English Village study, Gary Patronek emphasizes the importance of viewing such predation in the larger context. “When the birds were counted,” writes Patronek, former Director of the Center for Animals and Public Policy at the Cummings School, and one of the founders of the Hoarding of Animals Research Consortium, “they represented the postwinter population prior to hatching of spring chicks. By the year’s end, the actual sparrow population in the village numbered in the thousands, and the 130 birds caught represented about 5 percent of that number.” [31]

Compensatory vs. Additive Predation
Then there is the critical distinction between compensatory and additive predation, something Churcher himself alluded to: “I don’t really go along with the idea of cats being a threat to wildlife. If the cats weren’t there, something else would be killing the sparrows or otherwise preventing them from breeding.” [32]

Two very interesting studies have generated compelling evidence that birds killed by cats are, on average, significantly less healthy than those killed through non-predatory events (e.g., collisions with buildings). [15, 33] In other words, these birds probably weren’t going to live long enough to contribute to the overall population numbers; predation was compensatory rather than additive. Relative to population impacts, then, the “accounting” of bird kills is far more complex than ABC suggests.

Additional Evidence
Many researchers have disputed the kind of broad, overreaching claims Lebbin et al. make about the impact of cats on bird population (and wildlife in general).

Biologist C.J. Mead, reviewing the deaths of “ringed” (banded) birds reported by the British public, suggests that cats may be responsible for 6.2–31.3 percent of bird deaths. “Overall,” writes Mead, “it is clear that cat predation is a significant cause of death for most of the species examined.” Nevertheless, Mead concludes:

“there is no clear evidence of cats threatening to harm the overall population level of any particular species… Indeed, cats have been kept as pets for many years and hundreds of generations of birds breeding in suburban and rural areas have had to contend with their predatory intentions.” [34]

Mike Fitzgerald and Dennis Turner come to essentially the same conclusion: “We consider that we do not have enough information yet to attempt to estimate on average how many birds a cat kills each year. And there are few, if any studies apart from island ones that actually demonstrate that cats have reduced bird populations.” [25]

In the context of TNR, however, focusing on such figures may be missing the point. “If the real objection to managed colonies is that it is unethical to put cats in a situation where they could potentially kill any wild creature,” writes Patronek, “then the ethical issue should be debated on its own merits without burdening the discussion with highly speculative numerical estimates for either wildlife mortality or cat predation.” [35]

“Whittling down guesses or extrapolations from limited observations by a factor of 10 or even 100 does not make these estimates any more credible, and the fact that they are the best available data is not sufficient to justify their use when the consequence may be extermination for cats… What I find inconsistent in an otherwise scientific debate about biodiversity is how indictment of cats has been pursued almost in spite of the evidence, and without regard to the differential effects of cats in carefully selected, managed colonies, versus that of free-roaming pets, owned farm cats, or truly feral animals. Assessment of well-being for any species is an imprecise and contentious process at best. Additional research is clearly needed concerning the welfare of these cats.” [35]

Trap-Neuter-Return
“Many well-intentioned but misguided people,” write Lebbin et al. “exacerbate feral cat problems through a technique called Trap, Neuter, Release (TNR), whereby colony cats are caught, spayed or neutered, and then returned to colonies to be fed by volunteers.” [2] Here, the authors trot out a classic verbal swipe, using the term Release instead of Return, implying a certain lack of planning, or even abandonment (with its legal implications).

They also imply that ABC is a resource for the “misguided.”

Stay Cats (Peep Show)
From The ABC Guide, the caption reads: “Managed feral cat colonies are a hazard to birds and attract the dumping of additional unwanted cats.” In fact, the photographer, Tina Lorien, tells me that these cats were photographed on the Island of Crete, where, it seems, even spayed/neutered pet cats are rather rare.

“Despite its apparent appeal,” Lebbin et al. continue, “few colonies managed under this system shrink, as the program takes more time than most volunteers are able to give, some cats are never caught, and the colonies often become dumping grounds for more unwanted cats.” [2]

Resources
Their claim that TNR programs are ineffective due to limited resources is unsubstantiated. More important, though, they ignore the fact that any feral cat management program is resource-intensive (as is any conservation effort, of course). Several successful TNR programs have been documented (see below), and countless more operate quietly, out of the spotlight.

It’s important to point out, too, that TNR is typically funded through private donations and the out-of-pocket purchases of volunteers. Trap-and-kill, on the other hand, is more likely to rely entirely on local tax dollars.

Sterilization
Their suggestion that all the cats need to be sterilized also lacks support. One often-cited population modeling study—included here more as a reference point than anything else—found that, in order to reduce colony population, approximately 75 percent of fertile cats would need to be sterilized. [36] However, this figure from Andersen, Martin, and Roemer takes into account no adoptions, though the authors point out that adoptions “are similar in effect to euthanasia because these cats are permanently removed from the free-roaming cat population.” [36]

Nor do Andersen et al. consider emigration between cat colonies, though they concede that “a substantial number of owned cats are reported to be adopted strays.” [36] “Substantial” is right—in 2003, Clifton suggested that “up to a third of all pet cats now appear to be recruited from the feral population.” [10]

TNR Successes
Though Lebbin et al. refuse to acknowledge it, TNR has had its share of successes. A 10-year TNR program in Rome, for example, yielded a “16–32 percent decrease on total cat number” across 103 managed colonies. [37] Detractors [38] like to focus on authors’ suggestion that “all these efforts without an effective education of people to control the reproduction of house cats (as a prevention for abandonment) are a waste of money, time and energy.” [37]

In fact, given the 21 percent rate of immigration “due to abandonment and spontaneous arrival,” [37] this colony reduction is quite remarkable. And, as Julie Levy, Maddie’s Professor of Shelter Medicine in the University of Florida’s College of Veterinary Medicine, points out, “such a decline is still beneficial to wildlife if no better alternative is available.” [39] (The “alternatives” ABC proposes—outlined below—are, at best, exactly that: no better.)

Levy, Gale, and Gale reported a 66 percent decline in the population of managed colonies on the University of Central Florida campus between 1991 and 2002, despite the arrival of stray or abandoned cats. [40] (In their paper, Levy et al. cite several other success stories.) And, in their telephone survey of 101 north-central Florida colony caretakers, Centonze and Levy reported “a 27 percent decrease in mean colony size within less than one year of beginning neutering.” [41]

One of the best-known TNR programs is ORCAT, run by the Ocean Reef Community Association, which, according to a 2004 paper, had reduced “overall population from approximately 2,000 cats to 500 cats.” [42] According to the ORCAT website, the population today is approximately 350, of which only about 250 are free-roaming.

Any TNR program contends with the unfortunate (and illegal) dumping of cats. But to suggest that TNR invites abandonment of cats is ridiculous. I’ve seen no research supporting such a claim. If people are determined to abandon their pet cat(s), I fail to see how the presence or absence of a nearby TNR program will affect that decision. On the other hand, cats dumped near a managed colony are far more likely to be adopted and/or sterilized—thereby mitigating their potential impact on the overall population of unowned cats.

Finally, it’s important to note that, although rapid decline—and eventual elimination through attrition—of managed colonies is the goal of TNR (and apparently the only acceptable outcome for the authors of The ABC Guide), reduced growth is not without its benefits. “Population stabilization,” writes Levy, is “a valid metric given that the status quo for unsterilized cats is rapid population growth.” [39]

Alternatives to TNR
Given their ongoing criticism of TNR, one might expect ABC to offer an alternative method of feral cat management—an approach against which to measure TNR (and against which TNR would, presumably, prove inferior). For the most part, though, ABC sidesteps the issue.

“Neutering and spaying pet cats,” write Lebbin et al., “is a humane method for reducing cat over-population.” True enough, but that doesn’t address the sizable population of unowned cats. Although The ABC Guide calls for readers to “make TNR and the feeding of cat colonies illegal,” [2] there’s no recommendation for what should be done with all of these cats.

I put this question to Lebbin and Parr during an ABC webinar celebrating the launch of the book earlier this month. “What we recommend,” said Parr, Vice President of ABC, “as an alternative to [TNR], is not abandoning cats in the first place.” Again, I don’t think there’s any disagreement on this point. Parr continued:

“Other options would be to house those cats in shelters or outdoor sanctuaries which could be managed. Clearly, it’s a huge problem, and the solutions to this are going be things we going to have to work together on for a long period of time, but certainly that would be my first reaction to that question.”

Really, we’re back to sanctuaries? Is this the best ABC has to offer? Almost.

Trap-and-Remove
In their book, Lebbin et al. point out, with obvious pride, that, “By 2004, feral cats had been successfully removed from at least 48 islands worldwide” (there’s another euphemism: removed). [2] A particular “success” is Ascension Island, where, the authors maintain, feral cats had reduced seabird numbers “by 98 percent, from 200 million to 400,000.” [2] As a result of “a multi-year eradication effort that began in 2001,” [2] birds have begun to return.

But, as is often the case, what’s left out of the story is far more interesting than what included.

Detailed accounts of feral cats eradication Marion Island provide a glimpse of the horrors involved. A 1992 paper reports 872 cats shot and 80 more trapped during 14,725 hours of hunting. “Present action” included “mass trapping and poisoning, and the possible use of trained dogs [was] being investigated.” [43] This was after the highly contagious feline panleucopenia virus (feline distemper) had been introduced to the island’s feral cat population, reducing the population by an average 29 percent annually between 1977 and 1982. [44]

On Macquarie Island successful eradication has had “dire” [45] consequences in the form of rapidly increasing rabbit and rodent populations. “In response, Federal and State governments in Australia have committed AU$24 million for an integrated rabbit, rat and mouse eradication programme.” [45]

Given the extent to which conservation efforts backfired on Macquarie Island—less than 50 square miles in size—one can only imagine the consequences and expense (to say nothing of the protests!) of a similar attempt in the continental U.S. But according to ABC, it seems to be either this or sanctuaries—for a population of feral cats they claim to be 60–120 million strong.

(To be fair, Lebbin et al. do offer this concession: “In some cases, invasive or overabundant species may not need to be eradicated, but simply reduced to levels such that they no longer pose a serious threat to native endangered species.” [2] Given their staunch opposition to TNR, however, I suspect this “offer”—which in any case would mean the killing of many millions of cats—does not apply to feral cats.)

The Current Approach
We do have some sense of how ineffective “traditional” feral cat management—a mix of trap-and-kill and inaction—has been. In an interview with Animal Sheltering magazine, Mark Kumpf, President of the National Animal Control Association President from 2007 to 2008, described this approach as “bailing the ocean with a thimble,” suggesting, too, that “the traditional methods that many communities use… are not necessarily the ones that communities are looking for today.” [46]

Clifton goes further, suggesting that trap-and-kill has actually backfired: “Regardless of motive,” writes Clifton, “the effect on the feral cat population replicates natural predation: the most frequent victims are the very young, the old, the disabled, and the ill. The healthiest animals usually escape to breed up to the carrying capacity of the habitat, if they can.” [10]

“Responding to the intensified mortality,” Clifton continues, “felis catus now bears an average litter of four. Nearly seven centuries of killing cats doubled the fecundity of the species.” [10]

Accountability
What Becky Robinson called a “new environmental witch hunt,” [1] I like to think of as a Trojan Horse. Disguised as good advice for responsible cat owners, ABC’s Cats Indoors! campaign has, since 1997, been used more to combat TNR than anything else.

With the publication of The ABC Guide, the authors had a chance to right some past wrongs by coming clean about the research surrounding predation, wildlife impacts, and TNR, as well as the true implications of their call to “make TNR and the feeding of cat colonies illegal.” [2] Instead, they elected for business as usual.

Facts vs. Human Connection
In doing so, ABC missed a golden opportunity to use its enormous influence for moving the discussion forward. (More recently, ABC took another big step backwards by endorsing a deeply flawed and irresponsible paper released by the University of Nebraska-Lincoln, once again sacrificing their integrity for some easy PR.)

But Fenwick, who’s been President and CEO since ABC’s founding in 1994, doesn’t seem to get it. “What have we learned about the opposition?” he asks rhetorically in the book’s preface.

“For one thing, every point of view has its own science and economics to support its contentions, whether it be pro- or anti- pesticide use, free-roaming cats, bird collisions with glass or towers, conflicts with fisheries, land conversion, wind energy, mining, timbering, climate change, or any other issue we consider in addressing bird conservation…” [2]

Fenwick seems to be suggesting that “the opposition” has its own science and economics, whereas ABC has, on its side: Science and Economics (a truly untenable position, in light of a recent ABC press release).

“Facts alone will not win these battles,” he continues, “but human connection might.”

Communication vs. Misinformation
I have to agree with Fenwick that facts alone are insufficient to engage the general public. It’s difficult, for instance, to convey the critical nature of climate change in terms of ocean temperatures rising a couple of degrees Celsius (a figure I use here only to make a point). Explain to people how deep the water may rise in their city or neighborhood, however, and you’re liable to get their attention.

But that’s not what ABC is doing. They have effectively dismissed any and all rigorous science, choosing instead to broadcast as loudly as possible their increasingly dire message—in spite of the science.

Fenwick’s analogy is not climate change, but human health and welfare:

“…no matter the issue, our opposition will unfailingly question our priorities. So, they ask, ‘Why are you blaming __________ when we know habitat loss is the real problem?’ when I am asked these questions, I reply first that we continue to add to our base of knowledge and thus improve decisions affecting bird populations; second, if winning the debate translates to financial gain for the debater, then that position cannot be truly unbiased; and third, isn’t it analogous that if heart disease is the greatest mortality factor in our species, then why do we spend so much money combating cancer and other diseases, poverty and hunger? Solving any single problem—for birds or humans—is insufficient for our cause. Thoughtful people understand that it is critical that we fight for birds and humans across the full, broad front of issues.” [2]

Fenwick’s medical research analogy is an interesting one, but not in the way he intended. Actually, I’m reminded of David Freedman’s profile of John Ioannidis, professor at the University of Ioannina medical school’s teaching hospital, which appeared in last month’s Atlantic. In the piece, Freedman describes a provocative 2005 article that garnered Ioannidis worldwide attention:

“The article spelled out his belief that researchers were frequently manipulating data analyses, chasing career-advancing findings rather than good science, and even using the peer-review process—in which journals ask researchers to help decide which studies to publish—to suppress opposing views.” [47]

Obviously not the image Fenwick was trying to convey—but far more fitting.

Attacking “the full, broad front of issues” simultaneously makes perfect sense, but promoting erroneous and deceptive scientific claims in order to marshal the support necessary is unethical, plain and simple.

We’re not talking about cancer research distracting us from research into heart disease, to use Fenwick’s metaphor. No, what he and ABC are doing—in their relentless persecution of free-roaming cats, at least—is akin to funneling critical resources into the bottling and marketing of snake oil:

There’s no science behind it, and no remedy in its consumption—whatever the dosage.

Literature Cited
1. Sterba, J.P. (2002, October 11). Tooth and Claw: Kill Kitty? Wall Street Journal, p. A.1,

2. Lebbin, D.J., Parr, M.J., and Fenwick, G.H., The American Bird Conservancy Guide to Bird Conservation. 2010, London: University of Chicago Press.

3. APPA, 2009–2010 APPA National Pet Owners Survey. 2009, American Pet Products Association: Greenwich, CT.

4. Clancy, E.A., Moore, A.S., and Bertone, E.R., “Evaluation of cat and owner characteristics and their relationships to outdoor access of owned cats.” Journal of the American Veterinary Medical Association. 2003. 222(11): p. 1541-1545. http://avmajournals.avma.org/doi/abs/10.2460/javma.2003.222.1541

5. Lord, L.K., “Attitudes toward and perceptions of free-roaming cats among individuals living in Ohio.” Journal of the American Veterinary Medical Association. 2008. 232(8): p. 1159-1167. http://avmajournals.avma.org/doi/abs/10.2460/javma.232.8.1159

6. Jessup, D.A., “The welfare of feral cats and wildlife.” Journal of the American Veterinary Medical Association. 2004. 225(9): p. 1377-1383. http://avmajournals.avma.org/doi/abs/10.2460/javma.2004.225.1377

7. Levy, J.K., et al., “Number of unowned free-roaming cats in a college community in the southern United States and characteristics of community residents who feed them.” Journal of the American Veterinary Medical Association. 2003. 223(2): p. 202-205. http://avmajournals.avma.org/doi/abs/10.2460/javma.2003.223.202

8. Patronek, G.J. and Rowan, A.N., “Editorial: Determining dog and cat numbers and population dynamics.” Anthrozoös. 1995. 8(4): p. 199–204.

9. Clifton, M. (2003) Roadkills of cats fall 90% in 10 years—are feral cats on their way out? http://www.animalpeoplenews.org/03/11/roadkills1103.html Accessed May 23, 2010.

10. Clifton, M. Where cats belong—and where they don’t. Animal People 2003 [cited 2009 December 24].  http://www.animalpeoplenews.org/03/6/wherecatsBelong6.03.html.

11. Dauphine, N. and Cooper, R.J., Impacts of Free-ranging Domestic Cats (Felis catus) on birds in the United States: A review of recent research with conservation and management recommendations, in Fourth International Partners in Flight Conference: Tundra to Tropics. 2009. p. 205–219. http://www.pwrc.usgs.gov/pif/pubs/McAllenProc/articles/PIF09_Anthropogenic%20Impacts/Dauphine_1_PIF09.pdf

12. Winter, L., “Trap-neuter-release programs: the reality and the impacts.” Journal of the American Veterinary Medical Association. 2004. 225(9): p. 1369-1376. http://avmajournals.avma.org/doi/abs/10.2460/javma.2004.225.1369

13. Fougere, B. Cats and wildlife in the urban environment—A review. in Urban Animal Management Conference. 2000.

14. Baker, P.J., et al., “Impact of predation by domestic cats Felis catus in an urban area.” Mammal Review. 2005. 35(3/4): p. 302-312. http://dx.doi.org/10.1111/j.1365-2907.2005.00071.x

15. Baker, P.J., et al., “Cats about town: is predation by free-ranging pet cats Felis catus likely to affect urban bird populations? Ibis. 2008. 150: p. 86-99. http://dx.doi.org/10.1111/j.1474-919X.2008.00836.x

16. Woods, M., McDonald, R.A., and Harris, S., “Predation of wildlife by domestic cats Felis catus in Great Britain.” Mammal Review. 2003. 33(2): p. 174-188. http://dx.doi.org/10.1046/j.1365-2907.2003.00017.x

17. Churcher, P.B. and Lawton, J.H., “Predation by domestic cats in an English village.” Journal of Zoology. 1987. 212(3): p. 439-455. http://dx.doi.org/10.1111/j.1469-7998.1987.tb02915.x

18. Fiore, C.A., The Ecological Implications of Urban Domestic Cat (Felis catus) Predation on Birds In the City of Wichita, Kansas, in College of Liberal Arts and Sciences. 2000, Wichita State University: Wichita, Kansas.

19. George, W., “Domestic cats as predators and factors in winter shortages of raptor prey.” The Wilson Bulletin. 1974. 86(4): p. 384–396. http://elibrary.unm.edu/sora/Wilson/v086n04/p0384-p0396.pdf

20. Barratt, D.G., “Predation by house cats, Felis catus (L.), in Canberra, Australia. II. Factors affecting the amount of prey caught and estimates of the impact on wildlife.” Wildlife Research. 1998. 25(5): p. 475–487.

21. Lepczyk, C.A., Mertig, A.G., and Liu, J., “Landowners and cat predation across rural-to-urban landscapes.” Biological Conservation. 2003. 115(2): p. 191-201. http://www.sciencedirect.com/science/article/B6V5X-48D39DN-5/2/d27bfff8454a44161f8dc1ad7cc585ea

22. Crooks, K.R. and Soule, M.E., “Mesopredator release and avifaunal extinctions in a fragmented system.” Nature. 1999. 400(6744): p. 563–566. http://www.nature.com/nature/journal/v400/n6744/abs/400563a0.html

23. Coleman, J.S. and Temple, S.A., On the Prowl, in Wisconsin Natural Resources. 1996, Wisconsin Department of Natural Resources: Madison, WI. p. 4–8. http://dnr.wi.gov/wnrmag/html/stories/1996/dec96/cats.htm

24. Elliott, J. (1994, March 3–16). The Accused. The Sonoma County Independent, pp. 1, 10.

25. Fitzgerald, B.M. and Turner, D.C., Hunting Behaviour of domestic cats and their impact on prey populations, in The Domestic Cat: The biology of its behaviour, D.C. Turner and P.P.G. Bateson, Editors. 2000, Cambridge University Press: Cambridge, U.K.; New York. p. 151–175.

26. Leyhausen, P., Cat behavior: The predatory and social behavior of domestic and wild cats. Garland series in ethology. 1979, New York: Garland STPM Press.

27. Calhoon, R.E. and Haspel, C., “Urban Cat Populations Compared by Season, Subhabitat and Supplemental Feeding.” Journal of Animal Ecology. 1989. 58(1): p. 321–328.

28. Castillo, D. and Clarke, A.L., “Trap/Neuter/Release Methods Ineffective in Controlling Domestic Cat “Colonies” on Public Lands.” Natural Areas Journal. 2003. 23: p. 247–253.

29. Galbreath, R., “The tale of the lighthouse-keeper’s cat: Discovery and extinction of the Stephens Island wren (Traversia lyalli).” Notornis. 2004. 51: p. 193–200.

30. Medway, D.G., “The land bird fauna of Stephens Island, New Zealand in the early 1890s, and the cause of its demise.” Notornis. 2004. 51: p. 201–211.

31. Patronek, G.J., “Free-roaming and feral cats—their impact on wildlife and human beings.” Journal of the American Veterinary Medical Association. 1998. 212(2): p. 218–226.

32. n.a., What the Cat Dragged In, in Catnip. 1995, Tufts University School of Veterinary Medicine: Boston, MA. p. 4–6.

33. Møller, A.P. and Erritzøe, J., “Predation against birds with low immunocompetence.” Oecologia. 2000. 122(4): p. 500-504.

34. Mead, C.J., “Ringed birds killed by cats.” Mammal Review. 1982. 12(4): p. 183-186. http://dx.doi.org/10.1111/j.1365-2907.1982.tb00014.x

35. Patronek, G.J., “Letter to Editor.” Journal of the American Veterinary Medical Association. 1996. 209(10): p. 1686–1687.

36. Andersen, M.C., Martin, B.J., and Roemer, G.W., “Use of matrix population models to estimate the efficacy of euthanasia versus trap-neuter-return for management of free-roaming cats.” Journal of the American Veterinary Medical Association. 2004. 225(12): p. 1871-1876. http://avmajournals.avma.org/doi/abs/10.2460/javma.2004.225.1871

37. Natoli, E., et al., “Management of feral domestic cats in the urban environment of Rome (Italy).” Preventive Veterinary Medicine. 2006. 77(3-4): p. 180-185. http://www.sciencedirect.com/science/article/B6TBK-4M33VSW-1/2/0abfc80f245ab50e602f93060f88e6f9

38. Longcore, T., Rich, C., and Sullivan, L.M., “Critical Assessment of Claims Regarding Management of Feral Cats by Trap–Neuter–Return.” Conservation Biology. 2009. 23(4): p. 887–894.

39. Levy, J.K., Comments Re: “Critical Assessment”, Personal Communication. July 21, 2010.

40. Levy, J.K., Gale, D.W., and Gale, L.A., “Evaluation of the effect of a long-term trap-neuter-return and adoption program on a free-roaming cat population.” Journal of the American Veterinary Medical Association. 2003. 222(1): p. 42-46. http://avmajournals.avma.org/doi/abs/10.2460/javma.2003.222.42

41. Centonze, L.A. and Levy, J.K., “Characteristics of free-roaming cats and their caretakers.” Journal of the American Veterinary Medical Association. 2002. 220(11): p. 1627-1633. http://avmajournals.avma.org/doi/abs/10.2460/javma.2002.220.1627

42. Levy, J.K. and Crawford, P.C., “Humane strategies for controlling feral cat populations.” Journal of the American Veterinary Medical Association. 2004. 225(9): p. 1354-1360. http://avmajournals.avma.org/doi/abs/10.2460/javma.2004.225.1354

43. Bloomer, J.P. and Bester, M.N., “Control of feral cats on sub-Antarctic Marion Island, Indian Ocean.” Biological Conservation. 1992. 60(3): p. 211-219. http://www.sciencedirect.com/science/article/B6V5X-48XKBM6-T0/2/06492dd3a022e4a4f9e437a943dd1d8b

44. Rensburg, P.J.J.v., Skinner, J.D., and van Aarde, R.J., “Effects of Feline Panleucopaenia on the Population Characteristics of Feral Cats on Marion Island.” Journal of Applied Ecology. 1987. 24: p. 63–73.

45. Bergstrom, D.M., et al., “Indirect effects of invasive species removal devastate World Heritage Island.” Journal of Applied Ecology. 2009. 46(1): p. 73-81. http://dx.doi.org/10.1111/j.1365-2664.2008.01601.x

46. Hettinger, J., Taking a Broader View of Cats in the Community, in Animal Sheltering. 2008. p. 8–9. http://www.animalsheltering.org/resource_library/magazine_articles/sep_oct_2008/broader_view_of_cats.pdf

47. Freedman, D.H., Lies, Damned Lies, and Medical Science, in The Atlantic. 2010: Boston. p. 76–86. http://www.theatlantic.com/magazine/print/2010/11/lies-damned-lies-and-medical-science/8269/

Inside Job

Results from the American Pet Products Association’s 2009­­–2010 National Pet Owners Survey suggest that cats in this country are spending more time indoors than ever before. Although the proportion of owners keeping their cats inside at night has remained relatively steady since 1998 (at approximately 66%), their has been a 14% increase in daytime confinement (from 56% to 64%) over the same period. [1]

Indoor&Outdoor Access-APPA

It must be noted that owners were asked where they usually kept their cat(s), thereby raising some doubts about the accuracy of their responses. (There are actually two issues here: first is the level of truthfulness—did owners, intentionally or not, provide accurate information? But there is also the obvious ambiguity surrounding the term usually.) Nevertheless, these results correspond reasonably well with those of two earlier surveys: one commissioned by the American Bird Conservancy (ABC) in 1997, [2] the other conducted by Clancy et al. in 2001 [3] (the only other surveys I’ve found that investigated this issue specifically).

The ABC’s study (in which 250 cat owners participated in a telephone survey) indicated that “35% keep their cats indoors all of the time,” while “31% keep them indoors mostly with some outside access.” [2]

The 2001 survey included 168 cat owners, each of whom was part of the Feline Health Study, conducted at the Foster Hospital for Small Animals, Cummings School of Veterinary Medicine, Tufts University. Sixty percent of these cats were “strictly indoor cats,” while 40% “had some level of outdoor access.” [3] Probing further, Clancy et al. discovered that nearly half of the cats with outdoor access were outside for two or fewer hours a day. And 29% of them were outdoors for less than an hour each day. [3]

Considering the differences in sampling (most notably the fact that participants in the 2001 survey were all clients of a veterinary hospital, whereas APPA survey results for 2000 indicate that 27% of cat owners did not visit the vet in the previous 12 months), and the inherent uncertainty surrounding the terms mostly, usually, and some, the results of these three surveys are remarkably similar.

Counting Cats
Such findings are critical for developing accurate estimates of the number of birds killed by cats (assuming a reasonable level of accuracy is achievable, given the complexity of the issue). Simply put, cats that don’t go outside can’t kill birds.

Recognizing this, some researchers have inflated their figures for cats allowed outdoors. [4–6]

Dauphiné and Cooper, [6] for instance, cite the APPA’s 2007–2008 survey when referring to the number of owned cats in the U.S., but either ignored or overlooked its findings about confinement: 63% of owners reported that they kept their cat(s) indoors during the day, 70% during the night. (It’s also possible that the authors consulted only the APPA’s online summary, which probably didn’t include this information.)

By contrast, Dauphiné and Cooper claim that 65% of pet cats “are free-ranging outdoor cats for at least some portion of the day,” [6] citing not the APPA survey, but Linda Winter’s 2004 paper, “Trap-neuter-release programs: the reality and the impacts” (which can be downloaded here). Indeed, Winter, the former director of the ABC’s Cats Indoors! campaign, had suggested as much—misrepresenting the findings of a study commissioned by her own organization:

“A 1997 nationwide random telephone survey indicated that 66% of cat owners let their cats outdoors some or all of the time.” [7]

Double the proportion of cats allowed outdoors, and—just like that—the number of birds killed by pet cats doubles too. (Dauphiné and Cooper actually go much further, employing some grossly inflated predation rates as well.)

Counting Birds
Of course, such estimates do not necessarily relate directly to population impacts. The predation may be largely compensatory, for example; and there are source-sink dynamics to be considered as well.

Nevertheless, researchers persist—more often, it seems, in pursuit of staggering, media-friendly figures than a better understanding of what’s actually going on (e.g., Dauphiné and Cooper’s bumper-sticker-worthy “one billion birds”). As a result, the scientific literature is plagued with some rather spectacular failures where predation numbers are concerned (e.g., The Wisconsin Study, Christopher Lepczyk’s dissertation, Carol Fiore’s thesis, etc.).

*     *     *

The surprising level of agreement among the three “outdoor access” studies provides researchers a rare opportunity to agree among themselves. Which, in turn, could move us closer to an honest debate of the larger issues—arguing about which action is most appropriate, for instance, rather than about whose numbers are most valid.

Despite how results of these surveys have been—as recently as last year—overlooked, ignored, and misrepresented, I remain cautiously optimistic. As Patronek has suggested, “predation of songbirds tends to be noticed because it takes place during the day.” [8] It’s time predation research received the same kind of visibility. Sunlight, after all, is said to be the best of disinfectants.

Note: There is a an amendment to this post here.

Literature Cited
1. APPA, 2009–2010 APPA National Pet Owners Survey. 2009, American Pet Products Association: Greenwich, CT.

2. ABC, Human Attitudes and Behavior Regarding Cats. 1997, American Bird Conservancy: Washington, DC. http://www.abcbirds.org/abcprograms/policy/cats/materials/attitudes.pdf

3. Clancy, E.A., Moore, A.S., and Bertone, E.R., “Evaluation of cat and owner characteristics and their relationships to outdoor access of owned cats.” Journal of the American Veterinary Medical Association. 2003. 222(11): p. 1541-1545.

4. Coleman, J.S. and Temple, S.A., On the Prowl, in Wisconsin Natural Resources. 1996, Wisconsin Department of Natural Resources: Madison, WI. p. 4–8. http://dnr.wi.gov/wnrmag/html/stories/1996/dec96/cats.htm

5. Lepczyk, C.A., Mertig, A.G., and Liu, J., “Landowners and cat predation across rural-to-urban landscapes.” Biological Conservation. 2003. 115(2): p. 191-201.

6. Dauphiné, N. and Cooper, R.J., Impacts of Free-ranging Domestic Cats (Felis catus) on birds in the United States: A review of recent research with conservation and management recommendations, in Fourth International Partners in Flight Conference: Tundra to Tropics. 2009. p. 205–219.

7. Winter, L., “Trap-neuter-release programs: the reality and the impacts.” Journal of the American Veterinary Medical Association. 2004. 225(9): p. 1369-1376.

8. Patronek, G.J., “Free-roaming and feral cats—their impact on wildlife and human beings.” Journal of the American Veterinary Medical Association. 1998. 212(2): p. 218–226.

Repeat After Me

Listening to NPR’s On the Media this weekend, I was struck by a story (first broadcast in 2006) about how certain “sticky” numbers—however dubious—find their way into the media landscape and beyond, as On the Media co-host Brooke Gladstone noted:

“Four years ago, we delved into the mysterious number, said to be 50,000, of child predators online at any given time. It was cited by the NBC Dateline program “To Catch a Predator” and also by then Attorney General Alberto Gonzales.

But spokespersons for the FBI, the National Center for Missing and Exploited Children, and the Crimes against Children Research Center said it was not based on any research they were aware of. The A.G.’s office at the time, well, they said it came from Dateline.”

Wall Street Journal columnist Carl Bialik, who spoke to Gladstone for the story, described the process whereby such slippery figures gain traction:

“An interesting phenomenon of these numbers is that they’ll often be cited to an agency or some government body, and then a study will pick it up, and then the press will repeat it from that study. And then once it appears in the press, public officials will repeat it again, and now it’s become an official number.”

All of which sounds very familiar—Bialik could easily be describing the “official numbers” put out by so many TNR opponents. Among those that have gained the most currency are the predation estimates from the Wisconsin Study, the American Bird Conservancy’s figure for the proportion of birds in the diets of free-roaming cats, and Dauphiné and Cooper’s estimate of free-roaming cats in the U.S.

The Wisconsin Study
Despite its having been discredited long ago (see, for example, “Addressing the Wisconsin Study”), the Wisconsin Study continues to be cited as if its estimate of 8–219 million birds killed by the state’s rural cats [1] was credible. As recently as last year, Longcore et al. cited the work in their essay “Critical Assessment of Claims Regarding Management of Feral Cats by Trap–Neuter–Return.” [2]

This, despite the fact that—15 years earlier—co-author Stanley Temple told the press:

“The media has had a field day with this since we started. Those figures were from our proposal. They aren’t actual data; that was just our projection to show how bad it might be.” [3]

It’s true: the media has had a field day. Among the major newspapers to cite the Wisconsin Study are the Wall Street Journal [4], the New York Times [5], and the Los Angeles Times [6]. However, as I’ve described previously, it’s been the wildlife conservationists and bird advocates who’ve really had a field day with the Wisconsin Study:

  • The American Bird Conservancy (ABC) refers to the study, in its brochure Domestic Cat Predation on Birds and Other Wildlife. And the ABC goes one step further, pointing out that Coleman and Temple’s estimate was for rural cats, and that “suburban and urban cats add to that toll.” [7]
  • A 2009 article in Audubon Magazine suggests “cats were annually knocking off somewhere in the neighborhood of 8 million birds just in rural Wisconsin.” [9] To the magazine’s credit, they used Coleman and Temple’s low estimate—but none of the numbers from the Wisconsin Study are scientifically sound.

Birds Represent 20–30% of the Diet of Free-roaming Cats
According to an ABC report (downloadable from their website), “extensive studies of the feeding habits of domestic, free-roaming cats… show that approximately… 20 to 30 percent [of their diet] are birds.”

This, apparently, is the same report that Ellen Perry Berkeley debunked in her book, TNR Past Present and Future: A history of the trap-neuter-return movement, noting that the ABC’s 20–30% figure was not based on “extensive studies” at all. [10] In fact, just three sources were used: the now-classic “English Village” study by Churcher and Lawton [11], the Wisconsin Study (described above), and Mike Fitzgerald’s contribution to “The Domestic Cat: The Biology of Its Behaviour.” [12]

This gets a little complicated, so bear with me.

When Churcher and Lawton reported, “overall, birds comprised 35% of the total catch,” [11] they were referring to prey tallies recorded by study participants—not to the overall diets of the cats involved. Figures obtained through similar methods for the Wisconsin Study were 20–23%, [1, 13, 14] which the authors suggest—citing Fitzgerald’s comprehensive review of predation and dietary studies—are in line with other work:

“Extensive studies of the feeding habits of free-ranging domestic cats over 50 years and four continents [12] indicate that small mammals make up approximately 70% of these cats’ prey while birds make up about 20%.” [14]

But they’re comparing apples and oranges. Both the English Village and Wisconsin Studies report the percentage of birds returned as a portion of the “total catch,” whereas Fitzgerald reports percentage by frequency (i.e., the occurrence of birds in the stomach contents or scats of free-roaming cats), a point apparently lost on Coleman and Craven. The 21% figure [12] they refer to, then, is simply not comparable to their own (or that of the English Village study, a fact Churcher and Lawton acknowledge in their paper). As Berkeley notes, “this would put birds, as a portion of the diet of cats, at roughly 7 to 10.5 percent—nowhere near the ‘20 to 30 percent’ figures unleashed on the unscientific public by ABC!”

To put all of this into more familiar terms, it’s a bit like saying that coffee makes up 20–30% of the American diet versus saying that 20–30% of Americans drink coffee each day.

Nevertheless, 13 years after the ABC first published its report, the myth persists. The report—including the mistaken dietary figures—is still available. And the National Audubon Society has helped perpetuate the error, noting in its Resolution Regarding Control and Management of Feral and Free-Ranging Domestic Cats:

“…it has been estimated that birds represent 20–30% of the prey of feral and free-ranging domestic cats.”

Estimates of Free-roaming Cats
In January, Steve Holmer, the ABC’s Senior Policy Advisor, told the Los Angeles Times, “The latest estimates are that there are about . . . 160 million feral cats [nationwide].” Sounds like an awful lot of cats—nearly one for every two humans in the country. So where does this figure come from?

The source is a paper by Nico Dauphiné and Robert Cooper (which can be downloaded via the ABC website), presented at the Fourth International Partners in Flight conference. In it, Dauphiné and Cooper use some remarkably creative accounting, beginning with an unsubstantiated estimate of unowned cats, to which they add an inflated number of owned cats that spend time outdoors. In the end, they conclude that there are “117–157 million free-ranging cats in the United States.” [15] (For a more thorough explanation, see my previous post on the subject.)

Estimating the number of free-roaming cats wasn’t even the point of their paper. As the title—“Impacts of Free-ranging Domestic Cats (Felis catus) On Birds In the United States: A Review of Recent Research with Conservation and Management Recommendations”—suggests, the primary purpose was to describe the cats’ impact on birds. The authors’ exaggerated figure was merely a convenient route to their estimate of birds killed annually by cats: “a minimum of one billion birds” [15] (which, it should be clear, has the potential to become a very sticky number).

Holmer goes a step further, using only the upper limit of the range published by Dauphiné and Cooper, and making the subtle—but important—shift from free-ranging to feral cats.

When I asked him about this, he explained that those figures were “based on an earlier version of Nico’s latest paper and are now being updated in our materials.” I don’t know that any such changes were made; and in any event, the bogus estimate has already been published in the L.A. Times—as if it were true.

*     *     *

TNR opponents will often point to the vast collection of research studies, government reports, news accounts, and the like, that support their assertions. Drill down a bit into that collection, though, and they all start to look alike: the same familiar sources, the same flawed studies—and the same bogus figures. These figures have become the kind of “official numbers” Bialik refers to: quantitative poseurs owing their popularity to tireless—and irresponsible—repetition more than anything else.

Literature Cited
1. Coleman, J.S. and Temple, S.A., On the Prowl, in Wisconsin Natural Resources. 1996, Wisconsin Department of Natural Resources: Madison, WI. p. 4–8. http://dnr.wi.gov/wnrmag/html/stories/1996/dec96/cats.htm

2. Longcore, T., Rich, C., and Sullivan, L.M., “Critical Assessment of Claims Regarding Management of Feral Cats by Trap–Neuter–Return.” Conservation Biology. 2009. 23(4): p. 887–894.

3. Elliott, J., The Accused, in The Sonoma County Independent. 1994. p. 1, 10.

4. Sterba, J.P., Tooth and Claw: Kill Kitty?, in Wall Street Journal. 2002: New York. p. A.1

5. Barcott, B., Kill the Cat That Kills the Bird?, in New York Times. 2007: New York. http://www.nytimes.com/2007/12/02/magazine/02cats-v–birds-t.html

6. Kennedy, J.M., Killer Among Us, in Los Angeles Times. 2003: Los Angeles. http://articles.latimes.com/2003/dec/23/news/os-cat23

7. ABC, Domestic Cat Predation on Birds and Other Wildlife. n.d., American Bird Conservancy: The Plains, VA. www.abcbirds.org/abcprograms/policy/cats/materials/predation.pdf

8. FWS, Migratory Bird Mortality. 2002, U.S. Fish and Wildlife Service: Arlington, VA. www.fws.gov/birds/mortality-fact-sheet.pdf

9. Williams, T., Felines Fatale, in Audubon Magazine. 2009, National Audubon Society: New York, NY. http://www.audubonmagazine.org/incite/incite0909.html

10. Berkeley, E.P., TNR Past present and future: A history of the trap-neuter-return movement. 2004, Bethesda, MD: Alley Cat Allies.

11. Churcher, P.B. and Lawton, J.H., “Predation by domestic cats in an English village.” Journal of Zoology. 1987. 212(3): p. 439-455.

12. Fitzgerald, B.M., Diet of domestic cats and their impact on prey populations, in The Domestic cat: The biology of its behaviour, D.C. Turner and P.P.G. Bateson, Editors. 1988, Cambridge University Press: Cambridge; New York. p. 123–147.

13. Coleman, J.S. and Temple, S.A., Effects of Free-Ranging Cats on Wildlife: A Progress Report, in Fourth Eastern Wildlife Damaage Control Conference. 1989: University of Nebraska—Lincoln. p. 8–12. http://digitalcommons.unl.edu/ewdcc4/7

14. Coleman, J.S., Temple, S.A., and Craven, S.R., Cats and Wildlife: A Conservation Dilemma. 1997, University of Wisconsin, Wildlife Extension. http://forestandwildlifeecology.wisc.edu/wl_extension/catfly3.htm

15. Dauphiné, N. and Cooper, R.J., Impacts of Free-ranging Domestic Cats (Felis catus) on birds in the United States: A review of recent research with conservation and management recommendations, in Fourth International Partners in Flight Conference: Tundra to Tropics. 2009. p. 205–219.

The Work Speaks—Part 4: Mean Spirited

In April, Conservation Biology published a comment authored by Christopher A. Lepczyk, Nico Dauphiné, David M. Bird, Sheila Conant, Robert J. Cooper, David C. Duffy, Pamela Jo Hatley, Peter P. Marra, Elizabeth Stone, and Stanley A. Temple. In it, the authors “applaud the recent essay by Longcore et al. (2009) in raising the awareness about trap-neuter-return (TNR) to the conservation community,” [1] and puzzle at the lack of TNR opposition among the larger scientific community:

“…it may be that conservation biologists and wildlife ecologists believe the issue of feral cats has already been studied enough and that the work speaks for itself, suggesting that no further research is needed.”

In fact, “the work”—taken as a whole—is neither as rigorous nor as conclusive as Lepczyk et al. suggest. And far too much of it is plagued by exaggeration, misrepresentations, errors, and obvious bias. In Part 3 of this series, I discussed the distinction between compensatory and additive predation. Here, I’ll focus on how feral cat/TNR researchers often misuse averages to characterize skewed distributions, and how that error overestimates the impact of free-roaming cats on wildlife.

Something’s Askew
When a data set is skewed, it is inappropriate to use the mean, or average, as a measure of central tendency. The mean should be used only when the data set can be considered normal—the familiar bell curve. As Woods et al put it:

“the simple average number of animals brought home is not a useful measure of central tendency because of the skewed frequency distribution of the numbers of prey items brought home…” [2]

Studies of cat predation routinely reveal a positively skewed distribution; a few cats are responsible for many kills, while many of the cats kill few, if any, prey. So when researchers use the mean to calculate the total number of prey killed by cats in a particular area, they overestimate the cats’ impact.

How common is this? Very [see, for example, 3-9]. Of the many cat predation studies I’ve read, only a few [2, 10, 11] properly account for the skewed nature of this distribution. And others [12-17] often take these inflated figures at face value—as evidence of the impact cats have on wildlife. Published repeatedly, the erroneous estimates take on an undeserved legitimacy.

The proper method for handling skewed distributions involves data transformations, the details of which I won’t go into here. The important point is this: in the case of a positively skewed distribution, the back-transformed mean will always be less than the simple mean of the same data set.

Big Deal
Depending on the particular distribution, the difference between the simple mean and the back-transformed mean can be considerable. Let’s use the 2003 study by Woods et al. [2] to illustrate. In the case of mammals killed and returned home by pet cats, the back-transformed mean was 28.3% less than the simple mean. Or, put another way, the simple mean would have overestimated the number of mammals killed by 39.5%. Similarly, when all prey items were totaled (as depicted in the illustration above), the simple mean would have overestimated the total number off all prey (mammals, birds, herpetofauna, and “others”) by 46.9%.

On the other hand, the figures for birds appear to break the rule mentioned above. In this case, the back-transformed mean (4.1) is actually a bit higher than the simple mean (4.0). How can this be? In order to log-transform the data set, Woods et al. had to first eliminate all the instances where cats returned home no prey—you can’t take the logarithm of 0. So, they were actually working with two data sets. Now, the second data set—which includes only those cats that returned at least one prey item—is also highly positively skewed. As a point of reference, its simple mean was approximately 5.6 birds/cat, which, compared to the back-transformed mean, is an overestimation of 37.5%.

By now, it should be apparent that log-transformed means have another important advantage over simple means: because you have to eliminate those zeros from the data set, you are forced to focus only on the cats that returned prey home—which, of course, is the whole point of such studies! And in the case of this study, Woods et al. found that 20–30% of cats brought home either no birds or no mammals. And 8.6% of the cats brought home no prey at all over the course of the study.

Transforming a data set (and then back-transforming its mean) is simpler than it sounds, but Barratt offers a useful alternative, rule-of-thumb method (one echoed by Fitzgerald and Turner [18]):

“…median numbers of prey estimated or observed to be caught per year are approximately half the mean values, and are a better representation of the average predation by house cats based on these data.” [10]

So, whereas Dauphiné and Cooper (and others) suggest increasing such estimates by factors of two and three (“predation rates measured through prey returns may represent one half to less than one third of what pet cats actually kill…” [14]), they should, in fact, be reducing them by half.

Cat Ownership
There are other instances in which simple averages are used to describe similarly skewed distributions—with similar results. That is, they overestimate a particular characteristic—and not in the cats’ favor.

Cat ownership, for example, is not a normal distribution. Many people own one or two cats; a few people own many cats. This is precisely what Lepczyk et al. found in their 2003 study:

“The total number of free-ranging cats across all landscapes was 656, ranging from 1 to 30 per landowner…” [6]

In fact, about 113 (I’m estimating from the histogram printed in the report) of those landowners owned just one cat apiece. About 70 of them owned two cats. Only one—maybe two—owned 30 cats. And yet, Lepczyk et al. calculate an average of 2.59 cats/landowner (i.e., 656 cats/253 landowners who allow their cats outdoors), thereby substantially overestimating cat ownership—and, in turn, predation rates (which calculations are based upon the average number of cats/landowner).

Lepczyk et al. are not the only ones to make this mistake; several other researchers have done the same. [4, 5, 7-9]

Outdoor Access
The amount of time cats spend outdoors is also highly positively skewed, as is apparent from the 2003 survey conducted by Clancy, Moore, and Bertone. [19] Their work showed that nearly half of the cats with outdoor access were outside for two or fewer hours a day. And 29% were outdoors for less than an hour each day.

Among those researchers to overlook the skewed nature of this distribution are Kays and DeWan, who calculate an average of 8.35 hours/day. This greatly overestimates potential predation, and leads them to conclude—erroneously—that the actual number of prey killed by cats was “3.3 times greater than the rate estimated from prey brought home,” [9] as was discussed previously.

Compound Errors
Clearly, these errors are substantial—in some cases, doubling the apparent impact of cats on wildlife. Of course the errors are even more significant when one inflated figure is multiplied by another—as when Lepczyk et al. [6] multiply the average number of prey items returned by the average number of outdoor cats per owner. The resulting predation figures may well be four times greater than they should be! (Actually, there are additional problems with the authors’ predation estimates, which I’ll address in a future post).

*     *     *

The fact that such a fundamental mistake—one a student couldn’t get away with in a basic statistics course—is made so often is shocking. The fact that such errors slip past journal reviewers is inexcusable.

References
1. Lepczyk, C.A., et al., “What Conservation Biologists Can Do to Counter Trap-Neuter-Return: Response to Longcore et al.” Conservation Biology. 2010. 24(2): p. 627-629.

2. Woods, M., McDonald, R.A., and Harris, S., “Predation of wildlife by domestic cats Felis catus in Great Britain.” Mammal Review. 2003. 33(2): p. 174-188.

3. Coleman, J.S. and Temple, S.A., On the Prowl, in Wisconsin Natural Resources. 1996, Wisconsin Department of Natural Resources: Madison, WI. p. 4–8. http://dnr.wi.gov/wnrmag/html/stories/1996/dec96/cats.htm

4. Baker, P.J., et al., “Impact of predation by domestic cats Felis catus in an urban area.” Mammal Review. 2005. 35(3/4): p. 302-312.

5. Baker, P.J., et al., “Cats about town: is predation by free-ranging pet cats Felis catus likely to affect urban bird populations? Ibis. 2008. 150: p. 86-99.

6. Lepczyk, C.A., Mertig, A.G., and Liu, J., “Landowners and cat predation across rural-to-urban landscapes.” Biological Conservation. 2003. 115(2): p. 191-201.

7. Crooks, K.R., et al., “Exploratory Use of Track and Camera Surveys of Mammalian Carnivores in the Peloncillo and Chiricahua Mountains of Southeastern Arizona.” The Southwestern Naturalist. 2009. 53(4): p. 510-517.

8. van Heezik, Y., et al., “Do domestic cats impose an unsustainable harvest on urban bird populations? Biological Conservation. 143(1): p. 121-130.

9. Kays, R.W. and DeWan, A.A., “Ecological impact of inside/outside house cats around a suburban nature preserve.” Animal Conservation. 2004. 7(3): p. 273-283.

10. Barratt, D.G., “Predation by house cats, Felis catus (L.), in Canberra, Australia. II. Factors affecting the amount of prey caught and estimates of the impact on wildlife.” Wildlife Research. 1998. 25(5): p. 475–487.

11. Barratt, D.G., “Predation by House Cats, Felis catus (L.), in Canberra, Australia. I. Prey Composition and Preference.” Wildlife Research. 1997. 24(3): p. 263–277.

12. May, R.M., “Control of feline delinquency.” Nature. 1988. 332(March): p. 392-393.

13. Jessup, D.A., “The welfare of feral cats and wildlife.” Journal of the American Veterinary Medical Association. 2004. 225(9): p. 1377-1383.

14. Dauphiné, N. and Cooper, R.J., Impacts of Free-ranging Domestic Cats (Felis catus) on birds in the United States: A review of recent research with conservation and management recommendations, in Fourth International Partners in Flight Conference: Tundra to Tropics. 2010. p. 205–219

15. Longcore, T., Rich, C., and Sullivan, L.M., “Critical Assessment of Claims Regarding Management of Feral Cats by Trap–Neuter–Return.” Conservation Biology. 2009. 23(4): p. 887–894.

16. Winter, L., “Trap-neuter-release programs: the reality and the impacts.” Journal of the American Veterinary Medical Association. 2004. 225(9): p. 1369-1376.

17. Clarke, A.L. and Pacin, T., “Domestic cat “colonies” in natural areas: a growing species threat.” Natural Areas Journal. 2002. 22: p. 154–159.

18. Fitzgerald, B.M. and Turner, D.C., Hunting Behaviour of domestic cats and their impact on prey populations, in The Domestic Cat: The biology of its behaviour, D.C. Turner and P.P.G. Bateson, Editors. 2000, Cambridge University Press: Cambridge, U.K.; New York. p. 151–175.

19. Clancy, E.A., Moore, A.S., and Bertone, E.R., “Evaluation of cat and owner characteristics and their relationships to outdoor access of owned cats.” Journal of the American Veterinary Medical Association. 2003. 222(11): p. 1541-1545.

The Work Speaks—Part 1: Lost in Translation

In April, Conservation Biology published a comment authored by Christopher A. Lepczyk, Nico Dauphiné, David M. Bird, Sheila Conant, Robert J. Cooper, David C. Duffy, Pamela Jo Hatley, Peter P. Marra, Elizabeth Stone, and Stanley A. Temple. In it, the authors “applaud the recent essay by Longcore et al. (2009) in raising the awareness about trap-neuter-return (TNR) to the conservation community,” [1] and puzzle at the lack of TNR opposition among the larger scientific community:

“…it may be that conservation biologists and wildlife ecologists believe the issue of feral cats has already been studied enough and that the work speaks for itself, suggesting that no further research is needed.”

In fact, “the work”—taken as a whole—is neither as rigorous nor as conclusive as Lepczyk et al. suggest. And far too much of it is plagued by exaggerations, misrepresentations, errors, and obvious bias. For the next few posts, I’m going to present a sampling of its more serious flaws, beginning with how some researchers “reinterpret” work of others to suit their own purposes.

Tell It Like It Is
Studies of cat predation frequently cite the work of William G. George, who, in 1974, published a paper documenting his meticulous observations of the hunting behavior of three cats on his southern Illinois farm. “The results,” wrote George, “established a basis for examining the possibility that cat predation may result in depleted winter populations of microtine rodents and other prey of Red-tailed Hawks, Marsh Hawks, and American Kestrels.” [2]

Thirty years later, David A. Jessup interpreted things rather differently, giving George’s work an additional—and unwarranted—degree of certainty. Gone are the doubts that George expressed—first, regarding the impact of cat predation on rodent and other prey populations; second, regarding the relationship between these populations and the raptors that feed on them. For Jessup—who offers no additional evidence—it’s all very straightforward: “Feral cats also indirectly kill native predators by removing their food base.” [3]

More recently, Guttilla and Stapp seem to prefer Jessup’s take: “Human-subsidized cats… can spill over into less densely populated wildland areas where they reduce prey for native predators (George 1974).” [4]

If any additional work has been done on the subject (surely there are more cats in the area these days; how are the voles and raptors faring?), it seems to have gone unnoticed. Instead, Jessup, Guttilla, and Stapp (and others, too, no doubt) have simply rewritten George’s conclusion to suit their own purposes. Perhaps their version makes for a better story, but it’s rather poor science.

Credit Where Little/None Is Due
When the Lancet recently retracted a 1998 paper linking vaccinations to autism in children—“research” that sparked the ongoing backlash against vaccinations—it was headline news. The move prompted this criticism from one member of the British Parliament: “The Lancet article should never have been published, and its peer review system failed. The article should now be expunged from the academic record…”

At the risk of drawing too many parallels between the two papers, I think the same can be said for Coleman and Temple’s infamous “Wisconsin Study.” (On the other hand, it does serve a useful purpose as a red flag.) Actually, as Goldstein et al. point out, Coleman and Temple’s paper was never peer-reviewed (not necessarily a deal-breaker in my book, but such publications do warrant additional scrutiny), but achieved its mythical status by being cited ad nauseam in peer-reviewed journals, as well as the mainstream media.

Does anybody actually believe the numbers suggested by Coleman and Temple? Stanley Temple (one of the co-authors of the recent anti-feral cat/TNR comment in Conservation Biology) himself admitted their published figures “aren’t actual data; that was just our projection to show how bad it might be.” [5]

I don’t think Longcore et al. [6] or the editors at Conservation Biology put much stock in the Wisconsin Study—so why continue to publish “projections” that have been so thoroughly discredited? Because doing so strengthens their case, at least among those who don’t know any better—especially people outside the scientific community, including many journalists, policy makers, judges, and the general public.

In their recent comment, Lepczyk et al. suggest that conservation biologists and wildlife ecologists “look to the evolutionary biology community” [1] for an example of how to influence policy:

“When local policies or regulations are put forth that promote the teaching of creationism or intelligent design, the evolutionary biologists have responded in force from across the nation and world.” [1]

Let’s set aside for the moment all the baggage associated with their analogy. My question is this: Is the evolutionary biology community still publishing bogus “projections” from 13 years ago? I doubt it.

Check Your Premises
In their recent paper (available for download via the American Bird Conservancy (ABC) website), Dauphiné and Cooper arrive at their absurd figure of “117–157 million free-ranging cats in the United States,” [7] in part, by way of Jessup’s “estimated 60 to 100 million feral and abandoned cats in the United States.” [3]

So where does Jessup’s figure come from? We have no idea—there’s no citation. And Jessup is no authority on the subject—having conducted no studies or reviews of studies that quantify the feral cat population. What’s more, his “estimation” is among the highest figures published. Yet this is the shaky foundation upon which Dauphiné and Cooper attempt to build their subsequent argument.

The authors then add to the (dubious) number of feral cats the proportion of pet cats allowed outdoors. They refer to a 2004 paper by Linda Winter, director of ABC’s Cats Indoors! campaign, in which it was reported, “A 1997 nationwide random telephone survey indicated that 66% of cat owners let their cats outdoors some or all of the time.” [8]

That’s an interesting way to put it—Winter makes it sound like two-thirds of pet cats are essentially outdoor cats. But the surveycommissioned by ABC!—actually indicates that “35% keep their cats indoors all of the time” and “31% keep them indoors mostly with some outside access.” [9] The difference in wording is subtle, and hampered by imprecision—it all comes down to the meaning of some.

Winter’s 2004 paper implies that there are twice as many outdoor pet cats as was indicated in the original survey—an interpretation Dauphiné and Cooper seem to embrace. Had they looked further—and to a less biased source—they might have been able to get a better handle on the degree of outdoor access. For example: a 2003 survey conducted by Clancy, Moore, and Bertone [10] revealing that nearly half of the cats with outdoor access were outside for two or fewer hours a day. And 29% were outdoors for less than an hour each day.

Do these “part-timers” have the same impact on wildlife as feral cats? Dauphiné and Cooper would have us believe they do.

[Note: For a closer look at the flaws in Dauphiné and Cooper’s paper, download “One Billion Birds,” by Laurie D. Goldstein.]

The lesson? Credible research begins with a solid foundation; a weak foundation—one plagued with unsubstantiated claims—on the other hand, leads to pseudoscience.

Or worse. ABC’s Senior Policy Advisor, Steve Holmer, cited Dauphiné and Cooper’s bogus numbers when he spoke to the Los Angeles Times about his organization’s involvement with the legal battle against TNR. It’s like the Wisconsin Study all over again.

When All Else Fails, Look It Up
Though this would seem to be utterly obvious, it apparently bears repeating: Don’t cite work you haven’t actually read.

Isn’t this emphasized in all graduate (indeed, undergraduate, too) programs? What grad student isn’t, at one time or another, tempted to take the easy way out—ride the coattails of somebody else who’s (presumably) done the real work? In addition to the ethical implications, such shortcuts tend to invite more immediate troubles, too. Again, George’s work (described above) provides an excellent case study. Below are some examples of how his work has been referenced in the cat predation literature:

“It is very unlikely that cats bring home all of the prey that they capture. What proportion they bring home has been little studied. George (1974) on a farm in Illinois USA found that three house cats, all adequately fed, brought home about 50% of the prey that they killed.” [11]

“George found that about 50% of prey were indeed brought home, with the other 50% being eaten, scavenged by other animals or simply not found.” [12]

“These approximations are probably underestimates, assuming that cats do not bring back all the prey that they kill.” [13]

Trouble is, George never said these things; what he said was:

“… the cats never ate or deposited prey where caught but instead carried it into a ‘delivery area,’ consisting of the house and lawn. The exclusive use of this delivery area was verified in 18 to 70 mammal captures per cat, as witnessed between early 1967 and 1971.” [2]

In 2000, Fitzgerald and Turner pointed out the fact that George’s work was being misrepresented, noting that the erroneous 50% figure “has been reported widely, though it is unfounded.” [14] Nevertheless, the myth persists—even in 2010.

“In Illinois, George (1974) found that only about half of animals killed by cats were provided to their owners, and in upstate New York, Kays and DeWan (2004) found that observed cat predation rates were 3.3 times higher than predation rates measured through prey returns to owners. Thus, predation rates measured through prey returns may represent one half to less than one third of what pet cats actually kill…” [7]

As Dauphiné and Cooper demonstrate, the “reinterpreted” version of George’s work makes for a very convenient multiplier—suddenly, every kill reported is doubled (or tripled, if Kays and DeWan are to be believed—and they’re not, but that’s a topic for another post). Never mind the fact that it has no basis in actual fact.

Getting a copy of George’s study isn’t difficult, especially with the inter-library loan services available today. To reference it—to use George’s work so that your own appears more credible—without ever having actually read it, is simply inexcusable. But citing it blindly suggests more than laziness—it points to a certain coziness that has no place in scientific discourse. Too much Kool-Aid drinking, and not enough honest research.

*     *     *

Scientists can (and do) look at identical results and come to very different conclusions. But misinterpreting, misrepresenting, or dismissing the conclusions of others, is something else altogether. As the above examples (and there are many, many more!) illustrate, this happens far too often in the feral cat/TNR literature. And if we can’t believe what researchers are saying about the work of others, why would we believe what they say about their own work?

Next, I’ll focus on some of the major flaws in the feral cat/TNR literature—beginning with small sample sizes

References
1. Lepczyk, C.A., et al., “What Conservation Biologists Can Do to Counter Trap-Neuter-Return: Response to Longcore et al.” Conservation Biology. 2010. 24(2): p. 627-629.

2. George, W., “Domestic cats as predators and factors in winter shortages of raptor prey.” The Wilson Bulletin. 1974. 86(4): p. 384–396.

3. Jessup, D.A., “The welfare of feral cats and wildlife.” Journal of the American Veterinary Medical Association. 2004. 225(9): p. 1377-1383.

4. Guttilla, D.A. and Stapp, P., “Effects of sterilization on movements of feral cats at a wildland-urban interface.” Journal of Mammalogy. 2010. 91(2): p. 482-489.

5. Elliott, J., The Accused, in The Sonoma County Independent. 1994. p. 1, 10

6. Longcore, T., Rich, C., and Sullivan, L.M., “Critical Assessment of Claims Regarding Management of Feral Cats by Trap–Neuter–Return.” Conservation Biology. 2009. 23(4): p. 887–894.

7. Dauphiné, N. and Cooper, R.J., Impacts of Free-ranging Domestic Cats (Felis catus) on birds in the United States: A review of recent research with conservation and management recommendations, in Fourth International Partners in Flight Conference: Tundra to Tropics. 2010. p. 205–219

8. Winter, L., “Trap-neuter-release programs: the reality and the impacts.” Journal of the American Veterinary Medical Association. 2004. 225(9): p. 1369-1376.

9. ABC, Human Attitudes and Behavior Regarding Cats. 1997, American Bird Conservancy: Washington, DC. http://www.abcbirds.org/abcprograms/policy/cats/materials/attitude.pdf

10. Clancy, E.A., Moore, A.S., and Bertone, E.R., “Evaluation of cat and owner characteristics and their relationships to outdoor access of owned cats.” Journal of the American Veterinary Medical Association. 2003. 222(11): p. 1541-1545.

11. Churcher, P.B. and Lawton, J.H., “Predation by domestic cats in an English village.” Journal of Zoology. 1987. 212(3): p. 439-455.

12. May, R.M., “Control of feline delinquency.” Nature. 1988. 332(March): p. 392-393.

13. Crooks, K.R. and Soule, M.E., “Mesopredator release and avifaunal extinctions in a fragmented system.” Nature. 1999. 400(6744): p. 563.

14. Fitzgerald, B.M. and Turner, D.C., Hunting Behaviour of domestic cats and their impact on prey populations, in The Domestic Cat: The biology of its behaviour, D.C. Turner and P.P.G. Bateson, Editors. 2000, Cambridge University Press: Cambridge, U.K.; New York. p. 151–175.

No-Kill Austin? Not So Fast.

In March, Austin made headlines when its city council voted to adopt “Recommendations for the Implementation Plan to Reduce Animal Intake and Increase Live Animal Outcomes,” also known as the “No Kill Plan.” Over the weekend, it became clear just what an accomplishment this was, when Austin American-Statesman writer Mike Leggett devoted his column to the defense of his cat-killing neighbor. According to Leggett, the man’s killed more than 20 feral cats—he “just cannot tolerate what cats do to wild birds.” And, according to Leggett, “none of us should.”

Not exactly the no-kill spirit Austin had in mind, I’ll bet.

As if anticipating a backlash from Statesman readers, Leggett offered “all apologies to cat lovers,” before launching into his personal endorsement of cat killing. Judging by the online comments, there are a lot of people out there who doubt his sincerity. And what about Leggett’s neighbor, the executioner? He’s not a bad guy, either, apparently: “He doesn’t boast about it. Doesn’t take any pleasure in it.” Indeed, writes Leggett, “His family has owned cats.” What does that mean, exactly? Did his grandmother have a cat once? Hardly a ringing endorsement.

And nothing even approximating a defense. Leggett seems to be suggesting that it’s OK to kill cats as long as “your family has owned cats.” But how would that work, do you suppose? I mean, does this apply only to immediate family? Is there a statute of limitations involved? What if my family has owned only dogs—am I still allowed to kill cats?

Leggett’s argument doesn’t get any better when he looks to science for support, referring to the infamous “Wisconsin Study.” He doesn’t cite a specific source, but it’s likely, given which estimate he used, that it came from the U.S. Fish and Wildlife Service. Apparently, that’s good enough for Leggett. Never mind the fact that he’s writing about a controversial subject—which, one would hope, warrants a little bit of honest research.

Leggett also refers to a recent study published in The Journal of Mammalogy. Leggett’s take on this research: “Catching feral cats and neutering them did nothing to diminish the territory they hunted, nor did it stop them from hunting the birds that nest and rest on the island.” Anybody familiar with the topic of cat predation knows that results of island studies cannot simply be applied to continental studies. Or, to put it another way, Austin is not an island.

But there are more immediate issues with Leggett’s use of this research as “evidence.” The Catalina study [1] actually had very little to do with the hunting habits of cats at all. Essentially, these researchers measured how far 27 cats traveled across the island—to get a sense of their range—and also estimated the total number of cats living on Catalina. Everything else was extrapolation and speculation. There have been many studies of cat predation, but this is not one of them.

*     *     *

What comes through loud and clear (despite his disingenuous attempts to suggest otherwise: “I know killing cats is not for everyone. I know I don’t want to do it.”) is that Leggett simply doesn’t like cats. And he’s looking for whatever support he can find to justify their being killed. But he’s done something far worse. By presenting his endorsement as something justified scientifically—in a major newspaper—Leggett has crossed another line altogether.

If Leggett wants to engage in the feral cat/TNR debate, then he should do so honestly. His recent column—lacking even the pretense of a genuine journalistic endeavor—demonstrates an inexcusable lack of professional integrity. And the same can be said for the editorial staff across whose desks his article passed. What value did they suppose it would add to the paper? To the lives of its readers? Is it any wonder newspapers are in decline?

References
1. Guttilla, D.A. and Stapp, P., “Effects of sterilization on movements of feral cats at a wildland-urban interface.” Journal of Mammalogy. 91(2): p. 482-489.

A Critical Assessment of “Critical Assessment”—Part 2

The second in a series of posts that breaks down my critique of the essay “Critical Assessment of Claims Regarding Management of Feral Cats by Trap-Neuter-Return” (Conservation Biology, Volume 23, No. 4, 887–894) by Travis Longcore, Catherine Rich, and Lauren M. Sullivan.

Like so many others interested in blaming cats for declining bird populations, Longcore et al. refer to a 1996 article in Wisconsin Natural Resources magazine [1], in which the authors estimate that 8–219 million birds are killed annually by “free-ranging rural cats” in the state. More than any other work, the “Wisconsin Study” (which is actually a series of articles, the first being published in 1993 [2]) has been used as “evidence” against advocates for free-roaming cats in general, and TNR in particular.

In my previous post, I referred only briefly to Coleman and Temple’s work; in fact, careful scrutiny is in order. Among the study’s more notable flaws:

  • Its “estimate that 23 percent of [cats’] diet consists of birds” is well above the 7–10.5% figure suggested by Fitzgerald, [3] one of the world’s foremost experts on the subject (for a detailed account, see Ellen Perry Berkeley’s 2004 book, TNR Past present and future: A history of the trap-neuter-return movement [4]). In fact, Coleman and Temple cite Fitzgerald’s work, making the error all the more egregious.
  • Coleman and Temple assume that all cats hunt; in fact, it has been suggested that only 35–56% of cats are hunters. [5,6]
  • Their figures for cat density, too, have been challenged. [7]

For a more complete critique of the Wisconsin Study, download the 2003 report by Laurie D. Goldstein, Christine L. O’Keefe, and Heidi L. Bickel at Stray Pet Advocacy.

Now 14 years old, the Wisconsin Study has achieved mythical status—but not in a good way. I suppose it’s because the numbers are so impressive. Forget the fact that they’re essentially fictitious—they’re simply too tempting for people who see cats as the primary reason for declining bird populations. James Tantillo, a Lecturer in the Department of Natural Resources at Cornell University’s College of Agriculture and Life Sciences, is right on the money when he refers to Coleman and Temple’s estimate as an example of a “‘mutant statistic’ whose origins and genesis have been greatly lost to the people who cite it.” [8]

*     *     *

Among those who cite it are, of course, Longcore et al. But they failed to cite an important follow-up comment by one of the authors of the Wisconsin Study. In a 1994 interview, an “exasperated” Temple told The Sonoma County Independent:

The media has had a field day with this since we started. Those figures were from our proposal. They aren’t actual data; that was just our projection to show how bad it might be. [9]

More than the media, however, it’s been the wildlife conservationists and bird advocates who have had a field day with the Wisconsin Study. Here are just a few examples:

  • The American Bird Conservancy refers to the study in its brochure Domestic Cat Predation on Birds and Other Wildlife. But ABC goes one step further, pointing out that Coleman and Temple’s estimate was for rural cats, and that “suburban and urban cats add to that toll.” [10]
  • The U.S. Fish and Wildlife Service cites the study’s “intermediate” estimate of 39 million birds in its Migratory Bird Mortality Fact Sheet.
  • A recent article in Audubon Magazine suggests “cats were annually knocking off somewhere in the neighborhood of 8 million birds just in rural Wisconsin.” [11] To the magazine’s credit, they used Coleman and Temple’s low estimate (a surprise given the overall tone of the piece). Still, none of the numbers from the Wisconsin Study are scientifically sound (indeed, one can make a strong argument that none of the work constitutes actual research).

For Longcore et al. to cite the Wisconsin Study without even a mention of its numerous flaws, or the rather public admission by one of its authors that their estimates “aren’t actual data,” casts serious doubt on the entire paper. Either they didn’t know how flimsy Coleman and Temple’s work was, or they knew and ignored the facts. Neither approach makes for good science, of course.

*     *     *

Estimating the number of birds killed by cats is difficult enough; demonstrating that their predation is the cause of declining bird populations is an even greater challenge. Nevertheless, Longcore et al. suggest the evidence is both plentiful and compelling. I’ll lay out an argument to the contrary in my next post

References
1. Coleman, J. S., & Temple, S. A. (1996). On the Prowl. Wisconsin Natural Resources, 20, 4–8. http://www.dnr.state.wi.us/wnrmag/html/stories/1996/dec96/cats.htm

2. Coleman, J. S., & Temple, S. A. (1993). Rural Residents’ Free-Ranging Domestic Cats: A Survey. Wildlife Society Bulletin, 21(4), 381–390.

3. Fitzgerald, B. M. (1988). Diet of domestic cats and their impact on prey populations. In D. C. Turner & P. P. G. Bateson (Eds.), The Domestic cat: The biology of its behaviour (1st ed., pp. 123–147). Cambridge; New York: Cambridge University Press.

4. Berkeley, E. P. (2004). TNR Past present and future: A history of the trap-neuter-return movement. Bethesda, MD: Alley Cat Allies.

5. Baker, P. J., Molony, S. E., Stone, E., Cuthill, I. C., & Harris, S. (2008). Cats about town: is predation by free-ranging pet cats Felis catus likely to affect urban bird populations? Ibis, 150, 86-99.

6. Goldstein, L. D., O’Keefe, C. L., & Bickel, H. L. (2003). Addressing “The Wisconsin Study.” http://www.straypetadvocacy.org/html/wisconsin_study.html

7. Clifton, M. (2003). Where cats belong—and where they don’t. Animal People http://www.animalpeoplenews.org/03/6/wherecatsBelong6.03.html

8. Tantillo, J. A. (2006). Killing Cats and Killing Birds: Philosophical issues pertaining to feral cats. In J. R. August (Ed.), Consultations in Feline Internal Medicine Volume 5 (5th ed., pp. 701–708). St. Louis, MO: Elsevier Saunders.

9. Elliott, J. (1994, March 3–16). The Accused. The Sonoma County Independent, pp. 1, 10.

10. American Bird Conservancy (undated). Domestic Cat Predation on Birds and Other Wildlife. The Plains, VA. www.abcbirds.org/abcprograms/policy/cats/materials/predation.pdf

11. Williams, T. (2009). Felines Fatale. Audubon Magazine. http://www.audubonmagazine.org/incite/incite0909.html

A Critical Assessment of “Critical Assessment”—Part 1

The first in a series of posts that breaks down my critique of the essay “Critical Assessment of Claims Regarding Management of Feral Cats by Trap-Neuter-Return” (Conservation Biology, Volume 23, No. 4, 887–894) by Travis Longcore, Catherine Rich, and Lauren M. Sullivan.

How many birds are killed by cats? It’s a fair question. And if Longcore et al. are to be believed, we actually have a pretty good handle on this issue:

Feral and free-roaming cats are efficient predators, and their abundance results in substantial annual mortality of wildlife. Churcher and Lawton (1987) concluded that cats were responsible for 30% of the mortality of House Sparrows (Passer domesticus) in an English village. May (1988) extrapolated their results to an estimated 100 million birds and small mammals killed per year in England. Although this extrapolation is often criticized for the limited geographic scope and number of cats studied, Woods et al. (2003) confirmed and refined this result with a larger sample size and geographic area that included England, Scotland, and Wales. From a survey of cat owners that documented prey returned by 696 cats, Woods et al. (2003) estimated that the 9 million cats in Britain kill at least 52–63 million mammals, 25–29 million birds, and 4–6 million reptiles each summer. In North America Coleman and Temple (1996) developed estimates of cat densities in Wisconsin and associated mortality of 8–217 million birds per year.

The relationship between cat predation and bird populations is highly complex, and our understanding quite limited—something Longcore et al. only hint at. It doesn’t help matters that results of small, isolated studies are often extrapolated from rural to urban environments, from one region to another, and so forth. In 1995, Churcher himself cautioned against making such leaps: “I’d be very wary about extrapolating our results even for the rest of Britain, let alone America,” he told Catnip, a newsletter published by the Cummings School of Veterinary Medicine at Tufts University.

Actually, Churcher went much further: “I don’t really go along with the idea of cats being a threat to wildlife. If the cats weren’t there, something else would be killing the sparrows or otherwise preventing them from breeding.” [1] Although Longcore et al. seem eager to cite Churcher and Lawton’s now-classic work as “evidence” of the damage cats can do, they make no mention of Churcher’s later comments (just one of many examples of their tendency to “cherry pick” from the literature only the bits and pieces that fit neatly into their argument).

But back to the number of birds killed by cats. Many of the studies on the subject—including those cited by Longcore et al.—are quite flawed. Among the numerous issues that call into question their estimates are assumptions regarding the number of cats that actually hunt, the number of cats allowed outdoors, the number of cats that live in a particular area, and so forth. And then, of course, there are the risks inherent in estimating population numbers and characteristics based on a small sample size.

(In fact, Woods et al. go to some lengths to emphasize the limitations of their study, conceding, for example, that they “may have focused on predatory cats.” [2] This is just one of many reasons the authors cite for requesting that their work be treated “with requisite caution”—a request apparently ignored by Longcore et al.)

By referring uncritically to such studies, Longcore et al. give far greater importance to this work than is warranted. Repeating—and therefore reinforcing—figures known to be erroneous and/or misleading is simply irresponsible.

The fact that the “English village” study and “Wisconsin Study” have been so thoroughly discredited (see, for example, the comments of Nathan Winograd, director of the No Kill Advocacy Center, and a report by Laurie D. Goldstein, Christine L. O’Keefe, and Heidi L. Bickel) raises some unsettling questions about their inclusion in a paper billed as a “critical assessment.” For example: Are the authors interested enough in rigorous scientific inquiry to look beyond “the usual suspects” in their assessment of the key issues?

One might also wonder: Given the important literature that Longcore et al. choose to overlook, ignore, or dismiss (to be addressed in detail in future posts), what is their motivation for writing the essay in the first place? Actually, this question was answered in January, two months after the paper’s publication, when L.A. Superior Court Judge Thomas McKnew decided in favor of an injunction against publicly supported TNR in Los Angeles (LASC BS115483). The Urban Wildlands Group (for which Longcore serves as Science Director, and Rich as Executive Officer) was the lead petitioner in the case.

If “Critical Assessment” is any indication, the case had much more to do with politics, PR, and marketing than with science.

References
1. n.a. (1995). What the Cat Dragged In. Catnip, 4–6.

2. Woods, M., Mcdonald, R. A., & Harris, S. (2003). Predation of wildlife by domestic cats Felis catus in Great Britain. Mammal Review, 33(2), 174-188.

Works cited in “Critical Assessment” excerpt:

• Churcher, P. B., & Lawton, J. H. (1987). Predation by domestic cats in an English village. Journal of Zoology, 212(3), 439-455.
• Coleman, J. S., & Temple, S. A. (1996). On the Prowl. Wisconsin Natural Resources, 20, 4–8.
• May, R. M. (1988). Control of feline delinquency. Nature, 332, 392-393.