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).
Wanting to add to the subsequent online conversion, I drafted a response. Unfortunately, it exceeded the paper’s 1,400-character limit… by a factor of four. And that’s without the list of references.
Although I eventually trimmed it down sufficiently (and removed all hyperlinks, which are apparently interpreted as “profanity,” and thus prevent the comment from being posted), it seems a shame to lose all that hard work. And so, here’s the comment I wish I could have submitted:
For those not familiar with the infamous “Wisconsin Study,” a brief overview…
In 1995, Stanley Temple and John Coleman, a PhD student for whom Temple served as advisor, estimated “the number of birds killed annually by free-ranging cats in rural
Wisconsin” to be 7.8–219 million. [1] Contrary to what Temple implies here, though, their “estimates” were not based on work done in Wisconsin. Or by Temple and Coleman. Rather, their predation figures came from five earlier studies, [2–6] one of which (the source of their “intermediate” estimate, described in a 1996 paper on the same subject [7]) can be traced to “a single free-ranging Siamese cat” in New Kent County, VA. [6]
There are a number of flaws in the way Temple and Coleman calculated their estimated annual predation rate, beginning with their estimated population of free-roaming rural cats, for which the two “surveyed farmers and other rural residents in Wisconsin for information about their free-ranging (not house-bound) cats.” [8] A careful review of their work reveals sampling that vastly over-represented farmers—who typically kept twice as many cats on their property as compared to non-farm rural residents. Farmers made up 82 percent of the 785 survey respondents, but, according to U.S. Census data, comprised just 7.8 percent of rural households in Wisconsin. By contrast, only 131 non-farm households participated in the survey, despite the fact that they made up 92.2 percent of rural Wisconsin housing in 1990.
Although Temple and Coleman concede that “some cats kill no prey,” [1] their calculations make no such allowance. And their suggestion that “about 23 percent [of prey killed were] birds” (for which they cite “unpublished data” [1]) exceeds by a factor of two or three [9] what renowned researcher B.M. Fitzgerald found after analyzing 61 dietary studies from across the globe. [10] (Ironically, Temple and Coleman actually cite Fitzgerald’s work, arguing that their 23 percent figure “is consistent with other studies reporting that roughly 20–30 percent of free-ranging cats’ kills are birds.” [1])
In a 1994 interview with The Sonoma County Independent, Temple—described in the story as “exasperated when asked again to rehash his findings”—told reporter Jeff Elliot, “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.” [11]
Curiously, Temple told Conservation magazine writer John Carey last year that their estimate came from his and Coleman’s own data: 5.6 birds/cat/year multiplied by 1.4 million free-roaming rural cats in Wisconsin. [12] When I asked Temple about this via e-mail, he explained it this way:
“That the observed predation rate of at least 5.6 birds per cat per year would agree closely with the mean predation rate reported by several previous studies doesn’t seem all that surprising, and that the numbers turned out to be the same is simply a coincidence.”
Simply a coincidence? It’s possible, I suppose. But even if it is, that does nothing to explain all the flaws in the calculations he and Coleman used to grab headlines 20 years ago. And Temple was unwilling to go further, asking me to “refrain from turning this into a running dialogue,” a wish I honored.
Eight months later, though, he’s weighing in on the issue publicly, endorsing the “killer cat study” published by researchers at the Smithsonian and U.S. Fish and Wildlife Service. And once again, Temple’s conclusions aren’t supported by the evidence.
Indeed, what he describes as a “science-based estimate” alone raises questions of credibility. The 1.4–3.7 billion annual mortalities reported by these researchers (which they describe throughout their paper as a conservative estimate) represent an astonishing 28.5–75.5 percent of the estimated 4.7 billion landbirds in all of North America.
Were these figures even remotely accurate, the continent would have been devoid of birds long ago.
A careful examination of the model these researchers used reveals one inflated input after another, each one the result of the researchers’ very selective review of the literature on the subject. Garbage in, garbage out, as they say in the computer science field.
It’s important to understand, too, that predation—even at very high levels—does not necessarily lead to population-level impacts. Like all predators, cats tend to prey on the young, the old, the weak, or unhealthy. At least two studies have investigated this in great detail, revealing that birds killed by cats are, on average, significantly less healthy that birds killed through non-predatory events (e.g., collisions with windows or cars). [13, 14]
There’s an irony to all of this. Two of these three authors (Peter Marra and Tom Will) have advocated publicly for restrictions or outright bans on the trap-neuter-return method of free-roaming cat management. And Temple is taking the same position here. In fact, such policies would, it’s virtually guaranteed, actually increase the number of cats in the environment—and thereby any potential risk to the wildlife they claim to want to protect.
Temple didn’t have a plan twenty-some years ago, and he hasn’t got one now. Neither do Loss, Will, and Marra. (Temple’s suggestion—“trap-neuter-confine”—is too wildly unrealistic to even warrant a response.) What we’re seeing today is just more of the same long-running witch-hunt—dressed up as science (funded by U.S. taxpayers, naturally*), published, and sold to the public as rationale for policy decisions.
On the other hand, a generation later, much has changed. We are fed up with the culture of killing, for one thing. And, in this era of unprecedented access to information—coupled with the “force multiplier” of social media—the people who continue to promote it—however well they may disguise it—are no longer able to do so with the impunity they once enjoyed.
* Temple and Coleman’s work was funded by the University of Wisconsin, the Wisconsin Department of Natural Resources, and the USDA. [15]
Literature Cited
1. 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
2. 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
3. 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
4. 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
5. 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
6. 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
7. Coleman, J.S. and Temple, S.A., “On the Prowl.” Wisconsin Natural Resources. 1996. December. p. 4–8. http://dnr.wi.gov/wnrmag/html/stories/1996/dec96/cats.htm
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. Berkeley, E.P., TNR Past present and future: A history of the trap-neuter-return movement. 2004, Bethesda, MD: Alley Cat Allies.
10. 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.
11. Elliott, J. (1994, March 3–16). The Accused. The Sonoma County Independent, pp. 1, 10,
12. Carey, J., “Cat Fight.” Conservation. 2012. March. http://www.conservationmagazine.org/2012/03/cat-fight/
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. 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
15. Imrie, R. (1997, April 29). Professor Says Predatory Cats Are Taking Toll on Ecosystem. St. Paul Pioneer Press, p. 1B,