Laura Erickson's For the Birds

Last time I talked about my personal experiences as a rehabber dealing with birds injured by house cats. People with outdoor cats don’t like thinking about this. A mere ten years ago when people called the National Audubon Society to complain about cats, Audubon spokespeople said cats killed individual birds but didn’t cause any harm to avian populations—habitat loss was a far worse problem. But little by little, scientists studying the issue of cat predation have worked out hard numbers about just how many birds cats kill each year, and now ornithologists agree that keeping cats indoors or on leashes is a very high priority issue. Current estimates are that cats kill hundreds of millions of birds every year, as well as over a billion small mammals. Stan Temple at the University of Wisconsin in Madison calculated that every year cats kill in the vicinity of 140,000 game birds and 19 million songbirds in Wisconsin alone.

Cats are natural predators in their native Africa and southern Europe, where they were first domesticated. But when wild cats or other predators deplete prey species, they must move on or starve. Here in America, cats are subsidized by humans—given food, shelter, and medical treatment, so they don’t need to move on even if they remove most of the small animals. And because they are subsidized, large numbers of them can survive in a small area—natural predators must space themselves or starve. Worldwide, cats are believed to have been involved in the extinction of more bird species than any other cause except habitat destruction.

If killing birds and their prey isn’t enough, domestic cats also introduce diseases to wild species. Cats are the domestic animal most frequently reported to have rabies. They also spread feline leukemia virus to a mountain lion in California and may have infected the endangered Florida panther with feline distemper. Feline infectious peritonitis has been diagnosed in mountain lions and lynx, and feline immunodeficiency virus has been found in Florida panther and bobcat, presumably introduced by domestic cats.

If letting cats outside is bad for birds, it’s also bad for cats. Feline leukemia is transmitted from cat to cat, so cats that spend time outdoors are far more at risk than those kept indoors. Cats that toy with birds are the ones most likely to carry toxoplasmosis, too. Cats are hit by cars, injured in cat fights, and even occasionally killed by Great Horned Owls and foxes.

But despite all this many people feel like keeping their cats indoors is a form of incarceration. Cats do derive pleasure from stalking creatures in the real world. Some people try to help birds by putting a bell on the cat, but feline prowling movements are so steady and smooth that they have an easy time approaching prey without ringing the bell. And declawing cats doesn’t guarantee that they won’t kill birds, either. I once had an indoor cat named Sasha who could kill a chickadee within seconds of sneaking out, even after she was declawed. But declawed cats are very vulnerable to attacks by predators, so declawing is not way to protect bird OR cat. Fortunately, cats are adaptable animals, and adjust to life indoors rather quickly. If you really think your cat needs to spend time outside, at least let it out only at night. Unless they are desperate for food, cats tend to be visual hunters. At nighttime there are plenty of rodents about, but songbirds are hunkered down till first light, so aren’t moving enticingly. As long as kitty comes in by early morning, the bird kill will at least be minimized. It’s the very least we can do.