Cats on the Prowl
My renters abandoned their house in the middle of the summer a couple of years ago. I was upset, but not about losing money. My renters were house wrens, and they leased the one-bedroom home for a song.
I was more worried, just as they were, that the neighborhood had grown too dangerous. Two cats from next door claimed my backyard as their territory. That summer, the cats laid in wait for the wrens as they gathered twigs, grass and other tidbits for their nest.
The wrens kept their eyes on the cats and carefully chose nesting material from open areas where they felt safe. But when their first brood began to fledge, the real problem began. Whenever I was home and heard the parents' distinctive danger calls, I chased the cats from the young birds. Normally the wrens raised several broods in my backyard each summer. But that year, after one nesting, they headed for safer, cat-free ground.
A quick count revealed nine outdoor cats lived within a radius of three houses from mine. All the owners but one ignored the frantic cries of distraught birds trying to protect their young. "It's just part of nature," most replied.
Domesticated cats, however, have advantages over native predators that go after the same food. In a study on rural free-ranging cats, John S. Coleman and Stanley A. Temple of the University of Wisconsin in Madison, found "up to 114 cats per square mile, which is several times higher than the combined densities of all similar-sized native predators, such as foxes, skunks, opossums and raccoons."
In urban areas, the numbers can be even more alarming, especially in cities with large populations of feral cats. With a higher than normal number of predators, the bird population often suffers.
Large populations of cats are able to exist because of several reasons, according to researchers Coleman, Temple and Scott R. Craven. People feed cats, so their survival isn't dependent upon the amount of prey they find. Pet owners also protect them from disease and predation, factors that help control the number of other predators. Combine these advantages with a cat's ancestral drive to hunt, and the odds turn sharply against the birds.
Domesticated house cats most likely descended from the African wild cat. As northern Africans turned from hunting and gathering to agriculture around 5000 B.C., they encouraged these tabby-colored wild cats to live around their grain storage bins to eat rats and