Laura Erickson's For the Birds

Conservation– Keep your cat indoors.

There are about 78 million pet cats in the United States, about 48 million of which are allowed to roam outdoors. And at least as many stray and feral cats run wild. Most pet cats don’t kill many birds, but even small numbers add up when are so many cats, and a few cats kill a great many birds apiece. One early October morning during a migration fall-out when my son was in kindergarten, I found 17 dead Yellow-rumped and Palm Warblers on the ground on a two-block stretch, all killed by a single pet cat. Current estimates are that cats kill hundreds of millions of birds each year.

Sometimes people rescue birds from their cats. But these birds are invariably doomed. I was a rehabber for many years, and took in a wide variety of birds that had been injured by cats. To the unpracticed eye, many had no apparent injuries because bird feathers spread out, each one covering a lot of skin. Feathers can hide not only puncture wounds but also tears, gashes, and blood. Once a woman brought me a White-breasted Nuthatch that she was pretty sure had only lost a few tail feathers. But beneath the belly feathers, I saw in horror that the entire pygostyle (the fused vertebrae of the tail) had been ripped out, along with skin, muscles, and the tail-end of the intestines. I held the nuthatch as its life ebbed out. Meanwhile, the woman was driving home feeling virtuous for saving this little creature. Tragically, almost every cat-injured bird I ever cared for ended up dying.

Cat leash laws help birds. One excellent case in point is that of cardinals in Duluth. Individual cardinals have been appearing here for many decades, and in the 1990s more and more appeared in the city—enough that occasionally a male and a female would be in the same area at the same time, and people started calling me about cardinals nesting in their neighborhoods. But newly-fledged cardinals, before they get good at flying, spend a lot of time on the ground and in the low branches of shrubs, where cats have an easy time picking them off. Before the Duluth City Council passed a cat leash ordinance which took effect at the start of 2000, the highest number of cardinals ever recorded on a Duluth Christmas Bird Count was 6, and counts averaged about 2. The year the ordinance was passed, the CBC count for cardinals swelled to 17! In 2001, 20 cardinals were counted, in 2002, 15 cardinals were counted, and in 2003, 20 were tallied. I don’t believe that the burgeoning population immediately following the cat leash law is a coincidence.

Cats are, of course, natural predators. But unlike foxes, coyotes, hawks, owls, and other wild predators, we subsidize cats, providing them with food and shelter, attending to their injuries and taking care of them when they’re sick. On a single suburban block, three or four cats might thrive while a family of foxes would require far more space, and would move on or die out when they depleted their prey.

People often romanticize the wild nature of their cats. But over my lifetime, I’ve taken in four cats that I rescued as strays, and all four seemed perfectly content to stay indoors. Killing for a living is a hard life for a domesticated animal. One cup of dried cat food weighs 4-6 ounces, the same weight as 2 robins, 3 cardinals, or 15 chickadees, whose weight also includes their indigestible parts. So it takes a lot of birds to sustain a cat. And feeding feral cats hardly stops them from killing birds—cats have a natural instinct to chase and toy with birds and rodents whether or not they’re hungry, and the fitter a cat is, the more effective at killing it becomes.

Keeping cats indoors is not only good for birds; it’s good for cats and humans as well. The average lifespan of indoor cats is significantly longer than that of even the most well-protected outdoor cats, which can be crushed by cars, injured in fights with other cats, killed by dogs, foxes, or other predators, or contract serious diseases such as feline leukemia. People who allow their cats outdoors have significantly higher vet bills. And cats that toy with or feed on wild birds and mice are the ones most likely to carry toxoplasmosis, a protozoan organism which is extremely dangerous for our own unborn babies and newborns. Cats prefer to eliminate their wastes in loose, sandy soil, so they often use children’s sandboxes and cultivated gardens, exposing small children and gardeners to their droppings, which are rich in toxoplasmosis.

A great many people, including animal welfare groups and the American Veterinary Medical Association, recommend keeping cats indoors. Whether you love cats or birds or both, it’s the kind thing to do.