The Silent Treatment

“I don’t want to be sort of a poodle dog when I’m out there, and a friendly sort of presence in people’s lives,” explained New York Times reporter David Carr in an October 2011 interview with Fresh Air host Terry Gross, “and then come back and do something that’s really mean or aggressive.”

“And if it’s gonna be a hard story, one of things I always say is: This is gonna be a really serious story, and I’m asking very serious questions. And it behooves you to think it through and really work on answering, and defending yourself, because this is not a friendly story. And if they don’t engage, I just tell them: Well, you know what? You better put the nut-cup on, because this is not gonna be pleasant for anyone.

Two months later, I heard the interview as part of a year-end compilation of the show’s most memorable conversations. Carr’s comments struck a chord; just three weeks earlier, following the publication of “Perceived Predation Risk Reduces the Number of Offspring Songbirds Produce per Year” in Science, I was unable to get co-authors Liana Zanette and Michael Clinchy to “engage.”

Which I found both frustrating and puzzling.

Clearly, these two are eager to talk about domestic cats (see, for example, Clinchy’s comments in ScienceNOW and Zanette’s in the Winnipeg Free Press), even when their work has nothing at all to do with them (or, given the absurd methods employed, real-world predation in general). And here I am—pretty much all cats, all the time—reaching out, only to be snubbed.

During his Fresh Air interview, Carr refers to his October 23 column (“basically a screed,” he says), in which he took on big media—in particular, The Tribune Company and Gannett.

“I spent four days [in June] trying to get comments on Gannett [executive] bonuses, and on Sunday night they said, ‘We’re not going to comment on these bonuses.’ And I just said: Really? You’re a newspaper company. You’re a publicly held company. These bonuses are a matter of public record, and you have nothing to say about them? And I just found that appalling, and I think some of that was reflected in the piece.”

“Clearly,” added Carr, explaining the crux of his frustration, “they were living a life beyond consequence.”

Again, I’m reminded of Zanette and Clinchy. These two led a study in which contrived methods rendered the work nearly worthless—and then went on to misrepresent the study’s implications to the media. And what consequences will they face? None, I suspect. After all, the research did receive funding, and the resulting paper was published in a prestigious journal.

All of which paves the way for more of the same.

Not that Zanette and Clinchy are exceptional in this regard. Since launching this blog in April 2010, I’ve had numerous e-mail inquiries go unanswered. Scientists, journalists, officials of various agencies and organizations, etc.—people eager to get their message out, clearly, but unwilling to respond when that message is challenged. I’d always thought such scrutiny not only came with the territory, but was also welcome—a necessary tool for shaping better science, reporting, and policy.

Others apparently disagree. Among those with whom I have a decidedly one-way correspondence:

Melissa Miller, Wildlife Pathologist, California Department of Fish and Game
Miller was one of 14 co-authors to link the Type X strain of T. gondii—responsible for nearly three-quarters of sea otter infections, according to one study [1]—to wild felids (e.g., mountain lions and bobcats) rather than domestic cats.

“Three of the Type X-infected carnivores were wild felids (two mountain lions and a bobcat), but no domestic cats were Type X-positive. Examination of larger samples of wild and domestic felids will help clarify these initial findings. If Type X strains are detected more commonly from wild felids in subsequent studies, this could suggest that these animals are more important land-based sources of T. gondii for marine wildlife than are domestic cats.” [2]

Now, one needs to be very careful about making conclusions based on such small sample sizes. Nevertheless, given (1) the unprecedented (as far as I can tell) nature of these findings, and (2) the nature of the current “cat debate”—in which free-roaming cats are being vilified in both the scientific literature and mainstream media—this would certainly seem to be newsworthy.

And yet, just two paragraphs later, the paper goes into detail about the estimated mass of “feline fecal deposition” created by domestic cats in the communities near Estero Bay. Suddenly, the focus is back on domestic cats.

I asked her about this in July of 2010, but received no response.

(Nine months later, in a special section of the Spring issue of The Wildlife Professional, Miller and David Jessup (another of the 14 co-authors on the 2008 paper, and a colleague of Miller’s at the California Department of Fish and Game) were at it again, arguing simply, “the science points to cats.” [3])

Christine Stracey, Assistant professor of biology at Westminster College
“I thought the cats probably really hammered them when they were fledglings,” said Stracey, a former University of Florida doctoral student in a UF press release about her study of Northern mockingbirds, “but when they were in the nests, I didn’t really expect the cats to be a huge problem. But I was really wrong about that.”

Once again, the underlying science fails to live up to the dramatic press release. Dig into the details of Stracey’s study, and it becomes clear that she’s probably overestimating the strength of cats as urban predators. Perhaps considerably. In fact, her nest camera placement almost certainly biased her data.

In short, it seems Stracey observed predation by cats largely because she placed the cameras where the cats were.

“We need to think hard about the feral cat problem,” warns Stracey in the press release. But if, as she suggests, cats are a “huge problem,” then how to explain the fact—as Stracey notes in the very same press release—Northern mockingbirds have proven “able to not only live with us, but do really well living with us” [and our cats]? These birds are, as she puts it, “urban winners.”

I asked Stracey about all of this by way of e-mail, but received no response. My follow-up e-mail also went unanswered, but I did notice some Website traffic from the Salt Lake City area (where Westminster College is located) that same day. Coincidence? Could be.

The same goes for the traffic from Columbus, OH, following my e-mail to Amanda Rodewald, professor of wildlife ecology at Ohio State University.

“There are a lot of loud voices that deny cats are important predators of birds in our cities,” argued Rodewald (whose relationship to Stracey’s work remains a mystery) in the UF press release. “But this study shows clearly that cats were the dominant predator in this Florida system—and that wasn’t presumed, it was recorded on video, so it was fact.”

When I wrote to Rodewald, I identified myself as one of those “loud voices,” explaining that I wasn’t asking her to speak for Stracey, nor to defend the research. But, given her own research interest—and her obvious concern with Stracey’s work—perhaps she might be able to answer one question for me: What impact might we expect on the area’s Northern mockingbird populations if the cats were removed from the environment?

It was, apparently, one question too many.

Michael E. Grigg, National Institutes of Health
Like Zanette and Clinchy, Grigg, who serves as Chief of the Molecular Parasitology Unit at the National Institute of Allergy and Infectious Diseases (part of NIH), used a PR opportunity to misrepresent his work. “The most remarkable finding of our study,” notes Grigg in an NIH press release, “was the exacerbating role that [Sarcocystis] neurona appears to play in causing more severe disease symptoms in those animals that are also infected with T. gondii.”

So, the story is more complicated than is typically acknowledged—T. gondii may not be the culprit it’s so often made out to be.

But Grigg is still hanging his hat—in spite of his own findings—on simple environmental contamination:

“Identifying the threads that connect these parasites from wild and domestic land animals to marine mammals helps us to see ways that those threads might be cut… by, for example, managing feral cat and opossum populations, reducing run-off from urban areas near the coast, monitoring water quality and controlling erosion to prevent parasites from entering the marine food chain.”

In fact, Grigg and his colleagues found that “T. gondii infections peaked in 2007 then declined relative to S. neurona.” [4] Could it be that free-roaming domestic cats—generally presumed to be the primary source of T. gondii contamination—are also on the decline? TNR opponents don’t seem to think so.

And the researchers observed that infection rates associated with inland waters were no greater than in mammals found along the outer coast. Again, this raises serious questions about the role of domestic cats (which, one would presume, are more numerous inland). As do the numerous studies pointing to sources other than environmental contamination [5–7]—vertical transmission, [5] for example, and possibly ticks [8]—none of which Grigg and his colleagues acknowledge.

Then, of course, there are Grigg’s proposed solutions—first and foremost: “managing feral cat and opossum populations.” Even setting aside for the moment the numerous hurdles (e.g., ethical, economic, etc.) involved with the mass removal/reduction/eradication of these animals, what impact could we realistically expect in terms of T. gondii and/or S. neurona infections in marine mammals? (And what other consequences would we then face?)

I assume Grigg has given the subject considerable thought, but—so far, anyhow—he’s been unwilling to share those thoughts with me.

Steve Klett, Crocodile Lake National Wildlife Refuge Manager
I first ran across Klett’s name in the Florida Keys National Wildlife Refuges Complex Integrated Predator Management Plan/Draft Environmental Assessment, where he was cited as the source for the claim that “cats accounted for 77 percent of the mortality during a recent re-introduction of the Key Largo woodrat.” [9] If, as USFWS has suggested, there are only about 500 woodrats in the wild, [10] why not disclose precisely how many were involved in this “recent re-introduction”? Seventy-seven percent out of how many?

Thirteen, as far as I’ve been able to determine. That’s how many were apparently released in November 2010—following the release of 14 others in February. And, according to attorney and Endangered Species Act blogger Keith Rizzardi, 13 more were released in April 2011.

I e-mailed Klett in July, asking him to clarify that 77 percent figure (which, let’s face it: does a far better job of fanning the flames of the witch-hunt for feral cats than, say, “10 out of 13” does), but never heard back.

Klett retired in December, but Chad Anderson, USFWS biologist at the refuge, assures me that I can “look forward to that [77 percent figure] going from a personal comm. quote to a referenced white paper in the final IPM plan.”

I’m not holding my breath.

Timothy O’Hara, Reporter for the Key West Citizen
In an August 30, 2011 story for the Key West Citizen, Timothy O’Hara writes: “Research indicates that cat predation accounts for 50 percent to 77 percent of the deaths of Lower Keys marsh rabbits and Key Largo woodrats.”

One-half to three-quarters? Really?

Actually, no.

That 77 percent, of course, comes from Klett’s “personal communication”—and seems to reflect the 10 mortalities described above. (Another question I asked Klett was how they could be sure that cats were the culprits. It’s been suggested by a volunteer involved with the re-introductions that the evidence comes from camera traps on the refuge, but I know of no such information coming from refuge officials.)

The 50 percent figure, I’m quite sure, can be traced to Elizabeth Forys’ PhD work, done in the early 1990s on Navy-owned land on Boca Chica and Saddlebush Key. Forys found that 13 of 24 marsh rabbits monitored over the course of her two-and-a-half year study were killed by cats. [11] (USFWS misrepresents this, too, in its Predator Management Plan, once again omitting the number of mortalities: “Free-roaming domestic cat predation accounted for 50 percent of adult Lower Keys marsh rabbit mortality during radio telemetry studies…” [9])

Turns out, O’Hara wasn’t interested in being fact-checked; he never replied to my e-mail.

(If O’Hara is interested in real journalism, he might consider an investigative piece about how USFWS routinely plays misleads the public to whom they are ostensibly accountable.)

Darin Schroeder, ABC’s Vice President for Conservation Advocacy
In October, Schroeder sent a letter (PDF) to the mayors of the 50 largest cities in the country, urging them “to oppose Trap-Neuter-Re-abandon (TNR) programs and the outdoor feeding of cats as a feral cat management option.” In it, he trots out the usual laundry list of misleading complaints: predation, rabies, vague threats regarding the possible implications of the Endangered Species Act and the Migratory Bird Treaty Act, etc.

When I wrote to Schroeder, I made it clear that we need not get into all of this. I just wanted him to explain how feeding bans and policy directives opposing TNR would, as ABC suggests in its November 9 media release, “stop the spread of feral cats.” After all, common sense—and science—tells us that such policies (assuming they could be enforced, of course) would only drive population numbers upward. If, as Schroeder claims, there are “well-documented impacts of cat predation on wildlife,” how could an increase in the population of cats possibly be a benefit?

That was nearly two months ago now; I’m still waiting for Schroeder to connect the dots for me.

•     •     •

At the risk of stating the obvious, I’m not David Carr. And this is not the New York Times. I suppose my inquiries are easily ignored—coming, as they do, from an “outsider” whose blog has just 330-some subscribers. On the other hand—and not to put too fine a point on it—I’m asking the kinds of questions these people should be asked, by their colleagues, the press, and, in the case of the non-profits like the American Bird Conservancy, their donors.

That seems to be changing though—which means these folks had better get to work on better responses (or, as Carr suggests, put the nut-cup on). In the meantime, the fact that they refuse to engage speaks volumes.

Literature Cited
1.  Conrad, P.A., et al., “Transmission of Toxoplasma: Clues from the study of sea otters as sentinels of Toxoplasma gondii flow into the marine environment.” International Journal for Parasitology. 2005. 35(11-12): p. 1155-1168.

2. Miller, M.A., et al., “Type X Toxoplasma gondii in a wild mussel and terrestrial carnivores from coastal California: New linkages between terrestrial mammals, runoff and toxoplasmosis of sea otters.” International Journal for Parasitology. 2008. 38(11): p. 1319-1328.

3. Jessup, D.A. and Miller, M.A., “The Trickle-Down Effect.” The Wildlife Professional. 2011. 5(1): p. 62–64.

4. Gibson, A.K., et al., “Polyparasitism Is Associated with Increased Disease Severity in Toxoplasma gondii-Infected Marine Sentinel Species.” PLoS Neglected Tropical Diseases. 2011. 5(5): p. e1142.

5. Hide, G., et al., “Evidence for high levels of vertical transmission in Toxoplasma gondii.” Parasitology. 2009. 136(Special Issue 14): p. 1877-1885.

6. Prestrud, K.W., et al., “Serosurvey for Toxoplasma gondii in arctic foxes and possible sources of infection in the high Arctic of Svalbard.” Veterinary Parasitology. 2007. 150(1–2): p. 6–12.

7. Oksanen, A., et al., “Prevalence of Antibodies Against Toxoplasma gondii in Polar Bears (Ursus maritimus) From Svalbard and East Greenland.” Journal of Parasitology. 2009. 95(1): p. 89–94.

8. Sroka, J., Szymańska, J., and Wójcik-Fatla, A., “The occurrence of Toxoplasma gondii and Borrelia burgdorferi sensu lato in Ixodes ricinus ticks from eastern Poland with the use of PCR.” Annals of Agricultural and Environmental Medicine. 2009. 16(2): p. 313–319.

9. 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.

10. n.a., “Around the Refuge System: Florida and Arizona.” Refuge Update. 2010. 2. p. 17.

11. 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.

National Feral Cat Day 2011

National Feral Cat Day 2011 posterAs many of you are no doubt aware, Sunday is National Feral Cat Day, a holiday created 10 years ago by Alley Cat Allies “to raise awareness about feral cats, promote Trap-Neuter-Return, and recognize the millions of compassionate Americans who care for them.” This year, there are more than 320 events planned across all 50 states.

Even so, I’ll bet there are a number of scientists, journalists, and others who—despite devoting a great deal of attention to the topic the rest of the year—have allowed the holiday to sneak up on them, and therefore haven’t made plans. Here, then, are some suggestions for how some of these folks (listed in no particular order) might mark the 10th annual National Feral Cat Day.

•     •     •

Thank you to all those who—whether one day a year or year-round—raise awareness about, and care for, abandoned, stray, and feral cats, and promote TNR.

Video Games

Northern mockingbirdNorthern mockingbird. Photo courtesy of Wikimedia Commons and Ken Thomas.

“I thought the cats probably really hammered them when they were fledglings,” said former University of Florida doctoral student Christine Stracey in a press release about her study of Northern mockingbirds, “but when they were in the nests, I didn’t really expect the cats to be a huge problem. But I was really wrong about that.”

So, how big a problem are “the cats,” exactly?

No doubt it depends who you ask. But even Stracey, now an assistant professor of biology at Westminster College in Salt Lake City, seems to have rather different opinions on the matter.

In a paper documenting her research, to be published in Biological Conservation, Stracey readily acknowledges the limitations of her work:

“Before we can fully understand the role of nest predation in shaping urban bird communities, we need studies of a suite of species that do and do not thrive in urban environments and we need to study how predator diets change on a rural-urban gradient.” [1]

In the press release, however, Stracey’s not nearly so reserved: “We don’t see any reason why cats wouldn’t also eat cardinal nestlings, brown thrashers, towhees—anything else that is nesting in similar locations.” Noting that some of the cats caught on camera were wearing collars, she warns:

“People should not let their cats roam outdoors at all, but at the very least, keeping them inside at night will cut down on nest predation. Beyond that, we need to think hard about the feral cat problem.”

No wonder the story was picked up so enthusiastically by science sites (e.g., “To Kill a Mockingbird, Just Get a Cat” and “Cats No. 1 Predator to Urban Mockingbird Nests”).

While I agree completely that “we need to think hard about the feral cat problem,” I’m not convinced by Stracey’s work that cats are having any appreciable impact on the population of Gainesville’s Northern mockingbirds—never mind “anything else that is nesting in similar locations.” Indeed, Stracey herself describes the Northern mockingbird as an “urban winner,” and a “native species that is able to not only live with us, but do really well living with us.”

Well, which is it?

The Study
Stracey’s Biological Conservation paper combines the results of her work videotaping nest predators with data from 2005 and 2006, when she and her advisor, Scott Robinson, “documented [without the use of cameras] reduced nest predation in urban habitats at many of the same study sites.” [1]

The later work, conducted for her PhD thesis, involved collecting “data on nest predation rates at seven study sites (two parking lots, three residential neighborhoods, two pastures, and one wildlife preserve) in areas in and around Gainesville, FL between February and August of 2007–2008.” [1] In 2009, “one of the residential neighborhoods, one of the parking lots, and one of the pastures” were not included. [1]

Over this same period, Stracey used video cameras (clips are available at her Website) mounted at several nest locations (eight in 2007, 52 in 2008, and 84 in 2009) “to compare the identity of nest predators at nests in the urban matrix and non-urban habitats.” [1] Which, presumably, will shed light on the generally accepted urban nest predator paradox, which Stracey describes as the “mismatch between predation rates, which are often lower in urban areas, and predator abundance, which is often higher in urban areas.” [1]

In other words: if there are so many more predators is urban areas, why do predation levels tend to be lower?

Nest Survival
Using the logistic exposure method, Stracey calculated daily survival rates for Northern mockingbird nests for each habitat and each year of her study.

Here, the daily survival rate (DSR) is a measure of the odds that the eggs or nestlings will remain in the nest from one day to the next. A DSR of 90 percent, for example, means there’s a 90 percent chance—or nine-to-one odds—of a nest surviving from day to day. Or, to put it another way, there’s a 10 percent chance that the nest’s contents will be destroyed by a predator. (More generally, DSR includes any nest “failure,” but because Stracey was interested in predation, she “only considered nests that failed due to predation as ‘unsuccessful,’ thus her “daily survival rates… are not a measure of overall nest survival, but rather the probability of a nest escaping predation.’’ [1])

Nine-to-one odds sound great if you’re in Las Vegas, but no winning streak lasts forever. Over the course of the entire nest cycle, even a DSR of 96 or 97 percent takes its toll.

In the case of the Northern mockingbird, it takes about 13 days for the eggs to hatch and another 12 for the subsequent nestling stage. [2] (At least this is what Fischer found working in south Texas; Stracey doesn’t go into such details in her paper.) A DSR of 97 yields a 46.7 percent nest survival rate; a DSR of 96, only 36 percent (and this doesn’t take into account the additional “3 to 5 days for nest construction [and] 3 to 5 days for egg laying” observed by Fischer, who found that “a successful nest was used for an average of 33 days.” [2])

Assuming (conservatively) that there was essentially no risk of predation prior to the eggs being hatched, I used Stracey’s DSR data and a nest cycle of 25 days to estimate nest survival rates. (I also reordered the data to better compare habitats year-to-year.)

The result illustrates three important points:

  1. The residential neighborhoods—the only sites where cats were observed predating nests (more on that shortly)—are safer than either of the non-urban sites (the two pastures and the wildlife preserve) during 2005 and 2006, when cameras weren’t in use. (While I’m not suggesting that this difference is the result of the cameras, I’m not convinced that the cameras were as impartial as Stracey would have us believe—this, too, will be addressed shortly.) Indeed, even during 2007–2009, the results are, at best, mixed.
  2. The wildlife preserve, contrary to what its name suggests, fails to “outperform” the other habitats’ nest survival rates across all five years—sometimes (as in 2005, when the rate was just over 14 percent) spectacularly.
  3. Perhaps the most striking result, though, is the nest survival rates of Stracey’s two parking lot sites, which, in every year but 2008, top those of the other habitats—two to four times the rates documented at the wildlife preserve in some years. “Urban winner” is right. With apologies to Joni Mitchell, then, perhaps the best thing for the mockingbirds is to pave paradise and put up a parking lot.

Strong Nest Predators
My interest in Stracey’s work has less to do with nest survival itself, and much more to do with the role of cats in nest failure. Of the 24 predation events caught on tape in the residential neighborhoods, 17 (71 percent) were attributed to cats. By contrast, no cats were observed predating nests in the pastures or at the nature preserve. There, Cooper’s hawks were responsible for 15 of 33 (45 percent) predation events taking place at occupied nests. (One abandoned nest was raided by a blue jay.)

“I found no evidence,” writes Stracey, “that urban areas provide a refuge from strong nest predators.” [1]

“The strongest predator, cats, were essentially only found in urban areas, and Cooper’s hawks, the dominant predator in rural habitats, were found at roughly the same abundance in the two habitats (pers. obs.)… These results suggest that simple considerations of predator abundance do not explain habitat-specific patterns of nest predation.” [1]

Dig into the details of Stracey’s study, though, and it becomes clear that she’s probably overestimating the strength of cats as urban predators. In fact, her camera placement (intentionally or not) almost certainly biased her data.

Stracey didn’t use nest cameras in the parking lots “for fear of theft,” [1] a perfectly reasonable concession, but that means excluding approximately 36 percent (according to my calculations) of “urban” nest predation from her “whodunit” data set. And it’s easy to imagine that predation at these sites was skewed heavily toward predators other than cats (probably birds).

In terms of identifying individual predators, then, “urban” habitats include only residential neighborhoods.

Stracey also eliminated as candidates for video cameras 21 (7 percent) nests located more than 4 meters (approximately 13 feet) off the ground. These nests would seem to be largely inaccessible to cats. Similarly, she eliminated 18 of 124 (14.5 percent) of nests “located in trees that were right on the edge of a sidewalk or street that did not afford a place to hide the set-up.” [1] Again, perfectly understandable, but this almost certainly biased her results.

In short, it seems Stracey observed predation by cats largely because she placed the cameras where the cats were.

In addition to the 58 events caught on camera, “22 predation events were missed due to problems with the camera set-up, including drained batteries and damaged wires.” [1] Whether or not these incidents were evenly distributed across the three different habitats isn’t clear, and the implications could be significant.

As it is, the majority (58.6 percent) of videotaped predation occurred at non-urban sites; had the bulk of the technical problems (which accounted for 27.5 percent of the 80 predation events Stracey had the opportunity to videotape) also occurred at those sites, Stracey would have a more difficult time concluding, as she does, that “urban areas clearly do not provide a generalized refuge from nest predators.” [1]

Or maybe not. Even if Cooper’s hawks accounted for twice the nest predation as cats, I suspect the focus would merely shift from absolute predation rates to predation by non-native predators.

And finally there’s the question of whether the nest cameras had any effect on predation levels. Stracey says they didn’t, but it appears that she simply compared failure rates for nests with and without cameras for each year the cameras were in use.

Richardson et al. (whose work Stracey cites) point out that “expression of neophobia and wariness among larger mammals, corvids, and raptors is likely to differ according to the extent to which those predators have been persecuted [inline citations omitted]. Such variation should be considered when interpreting the results of camera studies from different habitats and among different groups of nest predators.” [3, emphasis mine]

“Although camera equipment at nests likely does attract the attention of generalist predators, we propose that many predators may not respond positively to these potentially novel objects. Some small rodents, in particular, can be highly neophobic, reacting to novel stimuli with extreme caution and often avoidance (Barnett and Cowan 1976, Innes 1978). Though seemingly fearless and inquisitive, wild corvids likewise can be highly neophobic, particularly toward objects that do not resemble natural food items (Coppinger 1969, Heinrich et al. 1995), which may explain why Thompson et al. (1999), expecting to document nest predation by American crows and blue jays based on their abundance at the study site and their reputation as nest predators, did not record predation by any corvids. Raptors may exhibit a degree of neophobia as well (Ruggiero et al. 1979). Both canids and corvids have demonstrated aversion toward remote camera equipment, possibly driven more by wariness of human activity than generalized neophobia (Hernandez et al. 1997, Harris and Knowlton 2001, Herranz et al. 2002, Sequin et al. 2003). For nest studies using remote cameras, neophobia may be reinforced by the fact that camera equipment is seldom left in place for >2 weeks. As nests fail or fledge, camera equipment is relocated to active nests at new locations.” [3]

To illustrate what they mean by persecution, Richardson et al. cite the work of Herranz et al. (one of those in-line citations omitted above): “In our study area, Black-billed Magpies are shot and trapped by hunters, and this may increase their awareness of strange objects in the environment.” [4]

It seems reasonable, then, to expect that cats—the most “welcome” (especially those kept as pets) of the predators in Stracey’s study—would also be the least neophobic. (Though, of course, from a historical perspective, cats are arguably the most persecuted of the lot.)

It may well be, then, that Stracey caught more cats on camera largely because (1) the cameras were located—literally—in the cats’ backyards, and (2) the cats weren’t put off by the equipment.

•     •     •

I asked Stracey about all of this by way of e-mail, but received no response. My follow-up e-mail also went unanswered, but I did notice some Website traffic from the Salt Lake City area that same day. Of course, it could be nothing more than coincidence.

The same can be said for the traffic I saw from Columbus, OH, late last week on the same day I contacted Dr. Amanda Rodewald, professor of wildlife ecology at Ohio State University. From what I can tell, Rodewald had nothing to do with Stracey’s mockingbird study; nevertheless, she was quoted in the UF press release:

“There are a lot of loud voices that deny cats are important predators of birds in our cities… But this study shows clearly that cats were the dominant predator in this Florida system—and that wasn’t presumed, it was recorded on video, so it was fact.”

So, I sent Rodewald an e-mail—identifying myself as one of those “loud voices.” I explained that I wasn’t asking her to speak for Stracey, nor to defend the research. But, given her own research interest—and her obvious concern with Stracey’s work—perhaps she might be able to answer one question for me: What impact might we expect on the area’s Northern mockingbird populations if the cats were removed from the environment?

No response yet—though it’s only been a few days. Still, I’m not holding my breath.

Literature Cited
1.  Stracey, C.M., “Resolving the urban nest predator paradox: The role of alternative foods for nest predators.” Biological Conservation. 2011. In Press, Corrected Proof.

2. Fischer, D.H., “Factors Affecting the Reproductive Success of the Northern Mockingbird in South Texas.” The Southwestern Naturalist. 1981. 26(3): p. 289–293.

3. Richardson, T.W., Gardali, T., and Jenkins, S.H., “Review and Meta-Analysis of Camera Effects on Avian Nest Success.” Journal of Wildlife Management. 2009. 73(2): p. 287–293.

4. Herranz, J., Yanes, M., and Suárez, F., “Does photo-monitoring affect nest predation? Journal of Field Ornithology. 2002. 73(1): p. 97–101.[0097:DPMANP]2.0.CO;2