Devolution In the Classroom: Three Editions of F. Gill’s “Ornithology”

For more than 20 years now, Gill’s classic text has been required reading for ornithology students. While the book’s attention to conservation issues has expanded over its three editions, its treatment of the impact of cats on bird populations reflects an unsettling shift away from science.

The hoards of students descending upon college campuses this fall will—despite the rise of the eco-friendly PDF and a great variety of online content—more often than not find their arms and backpacks stuffed with old-school printed-and-bound books. Among them will be Frank Gill’s Ornithology, a regular offering on campus bookstore shelves for 21 years now.

Gill’s Ornithology is, I’m told by one Vox Felina reader, “considered (at least in these parts) the text regarding ornithology.” From what I can tell, it’s popularity as required reading for third- and fourth-year undergraduates isn’t limited to any one region of the country. Indeed, according to Amazon.com, the book is “the classic text for the undergraduate ornithology course.” Its third edition, published in 2007, “maintains the scope and expertise that made the book so popular while incorporating a tremendous amount of new research.”

Unfortunately, none of this new research made it into the section—a single paragraph—meant to address the “threat” of cats. Indeed, students interested in this topic are better off with the first edition, published 17 years earlier.

First Edition
“The numbers of deaths attributable directly or indirectly to human actions each year during the 1970s are staggering,” writes Gill in the 1990 edition of Ornithology, “but are apparently minor in relation to the population level.” [1] Citing a 1979 U.S. Fish and Wildlife Service report by Richard C. Banks, Gill continues:

“Human activities are responsible for roughly 270 million bird deaths every year in the continental United States. This seemingly huge number is less than two percent of the 10 to 20 billion birds that inhabit the continental United States and appears to have no serious effect on the viability of any of the populations themselves, unlike human destruction of breeding habitat and interference with reproduction… Miscellaneous accidents such as impact with golf balls, electrocution by transmission lines, and cat predation, may amount to 3.5 million deaths a year.” [1]

Predation by cats (included under “All Other Indirect”), then, according to Banks, represents about 1.3 percent of overall human-caused mortality—a loss of, at most, 0.04 percent of the U.S. bird population annually. By contrast, hunting and “collision with man-made objects” combine to make up “about 90 percent of the avian mortality documented” in Banks’ report. [2]

Second Edition
Five years later, in the second edition, the story changes dramatically. Gill discards Banks’ reference to cats and uses his 270 million figure purely for dramatic effect—the set-up for a punch line in the form of Rich Stallcup’s back-of-the-envelope guesswork (which Stallcup himself considered “probably a low estimate” [3]). Gill even includes a bar chart to drive the point home. (Apparently, he didn’t find Banks’ pie chart compelling enough to include in the his first edition of Ornithology.)

“Human activities are directly responsible for roughly 270 million bird deaths every year in the continental United States, about 2 percent of the 10 to 20 billion birds that inhabit the continental United States (Banks 1979)… Dwarfing these losses are those attributable to predation by pets. Domesticated cats in North America may kill 4 million songbirds every day, or perhaps over a billion birds each year (Stallcup 1991). Millions of hungrier, feral (wild) cats add to this toll, which is not included in the estimate of 270 million bird deaths each year.” [4]

But Stallcup’s “estimate”—published in the Observer, a publication of the Point Reyes Bird Observatory (which Stallcup co-founded)—lacks even the slightest scientific justification. 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.” [3]).

“Let’s do a quick calculation, starting with numbers of pet cats. Population estimates of domestic house cats in the contiguous United States vary somewhat, but most agree the figure is between 50 and 60 million. On 3 March 1990, the San Francisco Chronicle gave the number as 57.9 million, ‘up 19 percent since 1984.’ For this assessment, let’s use 55 million.

“Some of these (maybe 10 percent) never go outside, and maybe another 10 percent are too old or too slow to catch anything. That leaves 44 million domestic cats hunting in gardens, marshes, fields, thickets, empty lots, and forests.

“It is impossible to know how many of those actively hunting animals catch how many birds, but the numbers are high. To be very conservative, say that only one in ten of those cats kills only one bird a day. This would yield a daily toll of 4.4 million songbirds!! Shocking, but true—and probably a low estimate (e.g., many cats get multiple birds a day).” [3]

It’s hardly surprising that Stallcup’s “estimate” grossly exaggerates predation rates since his research never went any further than the Chronicle’s mention of the U.S. pet cat population. His assumptions about how many of these cats go outdoors and their success as hunters stand in stark contrast to the trend suggested by pet owner survey results and various predation studies (some of which suggest that just 36–56 per­cent of cats are hunters. [5, 6])

(It was, no doubt, the “shocking” aspect of Stallcup’s numbers that appealed to Nico Dauphine, who, in her “Apocalypse Meow” presentation, acknowledges that Stallcup “didn’t do a study” but nevertheless concludes, inexplicably, that his “is a conservative estimate.”)

Unnatural Selection
So, how did Stallcup’s indefensible “estimate” make it into the standard ornithology textbook? It was, Gill told me recently by e-mail, “one of the few refs [he] could find.”

Referring to what he calls “the great cat debates,” Gill writes: “I claim no great expertise or authority… now or in the ancient histories of early textbook editions.”

Fair enough. Writing, editing, and revising multiple editions of Ornithology was an enormous undertaking—one for which Gill deserves much credit. But there was, available at the time, work by scientists who, unlike Stallcup actually studied predation. Indeed, even before the first edition of Ornithology was published, a great deal of work had been done—and compiled in the first edition (published in 1988) of The Domestic Cat: The Biology of Its Behaviour. In it, Mike Fitzgerald, one of the world’s foremost experts on the subject, reviewed 61 predation studies, concluding:

“Predation on songbirds by domestic cats is noticed because it takes place during the day, whereas much predation on mammals takes place at night. People generally enjoy having songbirds in their gardens, and providing food in winter may increase the numbers of birds. When cats kill some of these birds, people assume that cats are reducing the bird populations. However, although this predation is so visible, and unpopular, remarkably little attempt has been made to assess its impact on populations of songbirds.” [7]

Two years later, Fitzgerald had a brief letter on the subject published in Environmental Conservation. His comments are as relevant today as they were some 21 years ago:

“Before embarking… on programmes to educate the public so that they will pressure elected officials to act on ‘cat delinquency,’ we must discover what effect domestic cats really have on the wildlife populations in various urban localities—not merely what effect we assume they have on the basis of prey brought home by cats in one English village. Although we know what prey cats bring home in a few urban localities, we do not know what effect this predation has on the prey populations, or how the wildlife populations might differ if cat populations were reduced. Until we have this information we cannot ensure sound educational programmes. We should perhaps also try to discover what values urban people place on their wildlife and their pets—it seems likely that many of the people who love their pets also treasure the wildlife.” [8]

Surely, Fitzgerald’s work would have been more appropriate for, and useful to, Ornithology’s audience. Instead, unsuspecting undergraduates were treated to biased editorializing dressed up as science.

Third Edition
Gill tells me I wasn’t the first to “react… to the Stallcup paper,” and that the push-back was sufficient to prompt its removal from the third edition. Gone, too, is Banks’ report. Instead, Gill employs the now-common kitchen-sink approach, rattling off a litany of sins—borrowed, it seems, from the American Bird Conservancy.

“Domestic house cats in North America, for example, may kill hundreds of millions of songbirds each year. Farmland and barnyard cats kill roughly 39 million birds (and lots of mice, too) each year. Millions of hungrier, feral (wild) cats add to this toll. There is a common-sense solution. Letting cats roam outside the house shortens their expected life span from 12.5 years to 2.5 years and increases their risk of rabies, distemper, toxoplasmosis, and parasites. Evidence is mounting that cats help to spread diseases such as Asian bird flu. The message is clear: Keep pet cats inside for their own well being and for the future of backyard birds (http://www.abcbirds.org/cats/).” [9]

That 39 million birds figure, of course, comes from the infamous “Wisconsin Study,” the authors of which claim: “The most reasonable estimates indicate that 39 million birds are killed in the state each year.” [10] (The “reason” is, in fact, notably absent from Coleman and Temple’s figure—which can be traced to “a single free-ranging Siamese cat” that frequented a rural residential property in New Kent County, Virginia. [11])

Its implied use as a nationwide estimate, Gill says, was “a lapse.” The more serious lapse by far, though—not in copyediting but in judgment—is Gill’s endorsement of ABC.

A Constructive Approach
While he readily admits that he’s “not tracked nor verified [ABC’s] stats (and have paid precious little attention to the issue for almost 10 years),” Gill’s support is unwavering.

“ABC has taken a lead role on the cat-bird issues, generally with a constructive approach, which I applaud, given how polarized the debates can be.”

Constructive? As I’ve pointed out repeatedly, 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. (The Wildlife Society, though, which shares ABC’s penchant for bumper-sticker science and public discourse via sound-bites, is at least as eager to participate in the witch-hunt.)

Among the more glaring examples: senior policy advisor, Steve Holmer’s claim, quoted in the Los Angeles Times, that “there are about… 160 million feral cats [nationwide]” [12]; ABC’s promotion of “Feral Cats and Their Management,” with its absurd $17B economic impact “estimate,” published last year by the University of Nebraska-Lincoln; and the numerous errors, exaggerations, and misrepresentations that persist in their brochure Domestic Cat Predation On Birds and Other Wildlife (PDF)—including a rather significant blunder that Ellen Perry Berkeley brought to light seven years ago in her book TNR Past, Present and Future. [13]

A constructive approach begins, by necessity, with sound science. But when it comes to the issue of free-roaming cats, at least, ABC has demonstrated neither an interest nor an aptitude.

So how does such an organization end up as the sole resource listed in a widely-used undergraduate textbook? (One written by the same man who served as the National Audubon Society’s chief scientist from 1996 to 2005, no less.) What’s next—physiology and nutrition books directing students to the PepsiCo Website for their hydration lesson? Psychology texts deferring to Pfizer (makers of Zoloft) on selective serotonin reuptake inhibitors?

Frank Gill’s View
Gill never responded to my follow-up questions for this post. Still, his comments during our first exchange shed some light on his general attitude toward cats. “I have owned some wonderful (Siamese) cats in my life,” Gill explained, “so I do view them positively in many ways. But when they are dumped near a research station by returning vacationers and then eat the ringed birds I have been studying for many years, I take a different view.”

He followed this last sentence with a smiley-face emoticon, though the joke was clearly wasted on me.

“My informal view now is that managed feral cat colonies are potentially a serious threat to local bird populations, including both migrants that stopover in urban parks and endangered shorebird colonies. Sustaining those colonies should be prohibited generally. The return of coyotes to suburban landscapes is most welcome both to add a top predator to these ecosystems and to counter the numbers of feral cats as well as other midsized predators that impact breeding productivity. Just their presence in a neighborhood should persuade cat owners to keep their cats safely inside!”

•     •     •

It would be a mistake to suggest that the sloppy, flawed research I spend so much time critiquing can be traced directly to the second or third editions of Frank Gill’s textbook. Still, for many students, the path to a degree in ornithology (and onto related graduate degrees) leads through the book of the same name. As such, Ornithology may well be their first exposure to issues of population dynamics, conservation, and the like.

First impressions tend to be lasting ones. If, as a wide-eyed undergraduate, you “learned” that cats kill up to four million songbirds every day, how might that shape your future studies? Your career? What if you “learned” that such predation takes a $17B toll on the country annually?

Considering the tremendous burden we’re placing on future generations, why would we hobble them—before they even get started, really—with such misinformation and bias? They’ve got more than enough on their plate without having to fact-check their textbooks, too.

Literature Cited
1. Gill, F.B., Ornithology. 1st ed. 1990, New York: W.H. Freeman and Company. 660.

2. Banks, R.C., Special Scientific Report—Wildlife No. 215. 1979, United States Department of the Interior, Fish and Wildlife Service: Washington, DC. p. 16.

3. 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

4. Gill, F.B., Ornithology. 2nd ed. 1995, New York: W.H. Freeman and Company.

5. Perry, G. Cats—perceptions and misconceptions: Two recent studies about cats and how people see them. in Urban Animal Management Conference. 1999.

6. Millwood, J. and Heaton, T. The metropolitan domestic cat. in Urban Animal Management Conference. 1994.

7. 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.

8. Fitzgerald, B.M., “Is Cat Control Needed to Protect Urban Wildlife? Environmental Conservation. 1990. 17(02): p. 168-169. http://dx.doi.org/10.1017/S0376892900031970

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

10. Coleman, J.S., Temple, S.A., and Craven, S.R., “Cats and Wildlife: A Conservation Dilemma.” 1997. http://forestandwildlifeecology.wisc.edu/wl_extension/catfly3.htm

11. 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

12. Yoshino, K. (2010, January 17). A catfight over neutering program. Los Angeles Times, from http://www.latimes.com/news/local/la-me-feral-cats17-2010jan17,0,1225635.story

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

Apocalypse Meow: A Brief Review

Although Nico Dauphine has yet to be suspended from her duties at the Smithsonian’s Migratory Bird Center, it seems all the attention she’s received over the past week-and-a-half is making life rather uncomfortable for her supporters.

Last week, the National Zoo removed Dauphine’s online application for recruiting field assistants from its Website; this week, the University of Georgia’s Warnell School of Forestry and Natural Resources pulled her infamous “Apocalypse Meow” presentation from its site.

Which is understandable, given the circumstances. Far more puzzling is what it was doing there in the first place. The content is, not surprisingly, remarkably “selective” in terms of the science. What is surprising, though, is Dauphine’s delivery: she looks and sounds like a person without the least bit of conviction in the material she’s presenting. (Actually, she’s mostly reading to the audience—for 41 minutes.)

Dauphine (whose status hearing, originally scheduled for June 1, has been postponed until the 15th) presented “Apocalypse Meow: Free-ranging Cats and the Destruction of American Wildlife” in March of 2009, at Warnell (where she earned her PhD). Although she tells the audience that her goal “is to review and present the best available science that we have,” what she delivers is essentially no different from what she presented in her Partners In Flight conference paper [1]  (much of which is recycled in the current issue of The Wildlife Professional in a special section called “The Impact of Free Ranging Cats” [2]).

In other words: lots of exaggerated and misleading claims—and plenty of glaring omissions (i.e., the distinction between compensatory and additive predation).

Included in the section on predation are all the usual suspects: Longcore et al., [3] Coleman and Temple, [4] Crooks and Soulé, [5] PhD dissertations by both Christopher Lepczyk [6] and Cole Hawkins, [7] along with references to Linda Winter, David Jessup, [8] Pamela Jo Hatley, and others.

Among the highlights:

Invasive Species (of All Kinds)
Referring to island extinctions, Dauphine references a 2008 paper by Dov Sax and Steven Gaines—the same one the U.S. Fish and Wildlife Service cite (again, as “evidence” of island extinctions caused by cats) in their Florida Keys National Wildlife Refuges Complex Integrated Predator Management Plan/Draft Environmental Assessment, released earlier this year. As I point out in my response to the Keys plan, though, the Sax & Gaines paper isn’t about cats at all, but invasive plants. [9]

Magic Multipliers
For Dauphine, Lepczyk’s estimated 52 birds/cat/year predation rate simply isn’t enough. Studies using “prey returns,” she argues, underestimate the real damage. “Some studies using radio-collars and other techniques have shown that, typically, cats will return maybe one in three kills that they make, and sometimes not at all—so this is, again, a very conservative estimate of the actual number of kills.”

But Lepczyk’s PhD work wasn’t based on “prey returns” at all. He used a survey (one of many flaws), asking landowners, “how many dead or injured birds a week do all the cats bring in during the spring and summer months?” [6]

And the idea that cats return only one in every three kills? That’s based on some wonky analysis by Kays and DeWan, who studied the hunting behaviors of just 24 cats: 12 that returned prey home, and another 12 (11 pets and 1 feral) that were observed hunting for a total of 181 hours (anywhere from 4.8–46.5 hours per cat). [10]

The Selective Generalist
Dauphine stretches Hawkins’ conclusions (which Hawkins himself had already stretched past the point of being defensible) to suggest “a sort of preferential prey take for native species in some cases, by cats.” In other words, the cats might target native species.

Or not. Less than two minutes later, Dauphine’s making the case for hyperpredation—the devastating impact on native prey species (e.g., seabirds) brought about by a large population of cats supported largely by predation on an introduced prey species (e.g., rabbits).

From Millions to Billions
It’s difficult not to see Dauphine’s assertion that “it’s not productive to argue about the numbers”—which comes fairly early in her presentation—as disingenuous when she tries repeatedly to quantify predation levels (each of which is then qualified as “conservative”). Her use of a graph included in the second edition of Frank Gill’s Ornithology (shown below) is particularly interesting.

Now, the original source of Gill’s cat “data,” as Dauphine acknowledges, is Rich Stallcup’s 1991 article, “A reversible catastrophe”—inexplicably, the only source Gill cites when he refers to predation by cats: “Domesticated cats in North America may kill 4 million songbirds every day, or perhaps over a billion birds each year (Stallcup 1991). Millions of hungrier, feral (wild) cats add to this toll…” [11]

And where does Stallcup’s “data” come from?

“He simply argued—he didn’t do a study—he just argued that if one in ten of those cats kills one bird per day, already then we have 1.6 billion cat-killed birds per year,” explains Dauphine. “We actually know that the numbers are much larger. For instance, he’s starting out with 55 million pet cats; we know there are over 100 million outdoor cats in this country, and possibly far more. We also know from some studies that 80 percent of cats hunt, and the number of birds killed per year are probably much higher. So again, just to emphasize: this is a conservative estimate.”

In fact, Stallcup’s “estimate” is even flimsier than Dauphine suggests:

“Let’s do a quick calculation, starting with numbers of pet cats. Population estimates of domestic house cats in the contiguous United States vary somewhat, but most agree the figure is between 50 and 60 million. On 3 March 1990, the San Francisco Chronicle gave the number as 57.9 million, ‘up 19 percent since 1984.’ For this assessment, let’s use 55 million.

Some of these (maybe 10 percent) never go outside, and maybe another 10 percent are too old or too slow to catch anything. That leaves 44 million domestic cats hunting in gardens, marshes, fields, thickets, empty lots, and forests.

It is impossible to know how many of those actively hunting animals catch how many birds, but the numbers are high. To be very conservative, say that only one in ten of those cats kills only one bird a day. This would yield a daily toll of 4.4 million songbirds!! Shocking, but true—and probably a low estimate (e.g., many cats get multiple birds a day).” [12]

Shocking, yes. True? Why would anybody think so? (I can see the appeal for Dauphine, though: like her, Stallcup grossly overestimates the number of pet cats allowed outdoors.)

(The fact that this absurdity made it—however well disguised—into a standard ornithology textbook may explain a great deal about the positions frequently taken by today’s wildlife managers and conservation biologists regarding feral cats/TNR.)

Apocalypse Now
Perhaps the strangest—almost surreal—part of “Apocalypse Meow” comes when, to illustrate her point that the (over)heated TNR debate can “result in a lot of misunderstandings, misinformation, and hard feelings,” Dauphine refers to an e-mail sent out to the university’s CATSONCAMPUS listserv during the fierce TNR debate in Athens, which read in part:

“There are some folks in the area (and all over) who are not only Anti-TNR, they also hate felines so much that some of them want to round up the cats in the area and kill them.”

Two years later, this is pretty much what Nico Dauphine stands accused of.

Literature Cited
1. 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

2. Dauphine, N. and Cooper, R.J., “Pick One: Outdoor Cats or Conservation.” The Wildlife Professional. 2011. 5(1): p. 50–56.

3. 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. http://www.abcbirds.org/abcprograms/policy/cats/pdf/Management_claims_feral_cats.pdf

4. 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

5. Crooks, K.R. and Soulé, 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

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. http://www.sciencedirect.com/science/article/B6V5X-48D39DN-5/2/d27bfff8454a44161f8dc1ad7cc585ea

7. 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

8. 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

9. 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

10. 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. http://dx.doi.org/10.1017/S1367943004001489

www.nysm.nysed.gov/staffpubs/docs/15128.pdf

11. Gill, F.B., Ornithology. 2nd ed. 1995, New York: W.H. Freeman and Company.

12. 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