Local Cats Act as Guinea Pigs to Save Birds

The Gorilla kills fewer birds since wearing a harlequin collar.
Photograph by Susan Willson

Starting today, the owners of 58 Northern New York cats will keep every dead bird, shrew and chipmunk that their pet drags in.

They’ll freeze each little corpse individually in a plastic bag labeled with the date it was killed.

“If your cat chewed up a mouse and threw it back up, we’re collecting it,” says Susan Willson, associate professor of biology at St. Lawrence University, in Canton, northwest of the Adirondack Park. At the end of eight weeks, Willson will gather the baggies and identify the contents in an attempt to quantify whether putting a harlequin collar on a domestic cat reduces its toll on wildlife.

A study published this year by scientists from the Smithsonian Conservation Biology Institute and the Fish and Wildlife Service estimates that free-ranging domestic cats kill 1.4–3.7 billion birds and 6.9–20.7 billion mammals annually in the United States. Cats are believed to be second only to windows in causes of individual bird deaths.

Half of the 58 cats in Willson’s study will start out wearing their everyday, unobtrusive neckwear. The second group will begin wearing a Birdsbesafe collar, a fanned, brightly colored and patterned fabric cover designed to catch the eye of birds. Birds are equipped with sensitive color receptors that help them perceive hues more vividly than humans and other mammals.

Most of the study cats live in St. Lawrence County, but to compensate for local differences in habitat and bird migration patterns, the two cat groups will alternate Birdsbesafe collars on and off for two-week periods. Warblers, thrushes and other migrants are beginning to fly south to warmer winter territory, and the numbers and types of species in the North Country will vary over the next two months.

The inspiration for the study is a big black stray cat that escaped a house fire and subsequently survived in the wild by hunting. Willson adopted him and took to calling him “the Gorilla” because burn scars left the skin around his eyes and nose shiny and hairless.

“My cat, he’s like a professional killer. He would kill multiple birds per week and bring them home, which was horrifying,” says Willson, who is an avian ecologist and conservation biologist.

So she searched the Internet for ideas on how to lessen the impact of an inveterate outdoor cat. She found Birdsbesafe collar covers, created by a woman in Vermont who wanted to stop her own cat from killing birds. Willson ordered one, paying about $10. Once the Gorilla was festooned, he was comfortable but conspicuous—and no longer able to sneak up on adult birds. He still kills small mammals, which have limited color vision, and baby birds, which can’t fly.

The collar is not a solution to every problem, but it appears to provide an effective warning for fledged birds. Willson is applying scientific method to gauge how effective.

“This has huge conservation implications,” she says. “If this [collar] was available in big pet stores . . . you could potentially save millions of birds.”

The American Bird Conservancy recommends that pet owners keep cats indoors to reduce needless loss of birdlife. However, barn cats are allowed to roam expressly to kill mice, and plenty of people are aware of the ecological damage caused by cats yet continue to let them out. Elizabethan collars may offer a way to address at least part of the issue. If this experiment demonstrates a significant reduction in the number of birds killed, it will be interesting to see whether bird conservation groups embrace the collar—or whether it has the unintended consequence of making pet owners think it’s OK to let even more cats roam.

Correction: September 3, 2013

An earlier version of this article referred to Susan Willson as an assistant professor. She is now an associate professor.

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