As I continue to drill down into the “The impact of free-ranging domestic cats on wildlife of the United States”—tracking down and reading journal articles, compiling the data therein, etc.—I’m finding (not surprisingly) additional holes in the various claims made by Scott Loss, Tom Will, and Peter Marra. For example:

“Native species make up the majority of the birds preyed upon by cats. On average, only 33 percent of bird prey items identified to species were non-native species in 10 studies with 438 specimens of 58 species.” [1]

That’s quite a statement to make on the basis of just 10 studies (spanning 63 years*) and an average of fewer than eight specimens per species. And actually, one of the studies cited by Loss et al. was no study at all, but rather the Florida Fish and Wildlife Conservation Commission’s two-page brochure Impacts of Feral and Free-ranging Domestic Cats on Wildlife in Florida (PDF). Not only are there no “bird prey items identified to species,” the document relies heavily on claims made by the American Bird Conservancy (thus raising serious doubts about the agency’s assertion that “scientific data drives management decisions for fish and wildlife populations and their habitats”).

How nobody—neither the three authors nor the multiple reviewers—caught this is a bit of a mystery. Just a glance at the brochure’s title ought to raise eyebrows in light of the way it’s cited by Loss et al. On the other hand, mistakes like this do happen. And in this case, I’m willing to give the authors the benefit of the doubt—largely because there are so many other, far more substantive, problems with their paper.

Continue Reading »