I’ve been to Chicago and the surrounding area plenty of times, but I never thought to look for coyotes. I hadn’t realized that the animals have been expanding their territory over the last several hundred years, and they can now be found in many U.S. and Canadian cities, including Chicago. In many of these areas, coyotes are now the largest carnivores, at the top of the food web. And that might be affecting some of the animals we are more familiar with.
Urban coyotes have a varied diet, consisting mostly of small rodents, white-tailed deer, fruit (carnivores aren’t strictly meat eaters), bunnies and birds. They also eat a small number of cats, which led a group of scientists who are studying urban coyotes in the Chicago area to look into how coyotes and feral cats interact in the city’s suburbs. The results of their study appear in PLOS ONE.
Between February 2008 and September 2009, the researchers captured 43 cats in eight sites in the suburbs west of Chicago. They then took blood samples from the cats and fitted 39 with radiocollars (two cats were thought to be pets, one was too small for the collar, and one was so sick it was euthanized). Getting good data from the cats was difficult: A fifth of the cats died during the study period, a quarter were adopted, 13 percent had collars that didn’t last until the end of the study, 10 percent were never heard from again, and, in what is the most mysterious statement in the study, 23 percent “were removed from the system by cat advocates opposed to our research.” Despite the difficulties, however, the researchers were able to get good tracking data for a number of kitties, enough to map out several cats’ home ranges and plot them against the ranges of coyotes in the urban coyote project.
The cats and coyotes, the researchers found, did overlap a bit in their travels, but for the most part, cats stuck to areas around homes and buildings. The coyotes, in contrast, preferred natural habitats away from human development. “Coyotes in our system appear to inhibit cat use of the natural habitat fragments through a combination of predation and cat avoidance of coyote activity,” the researchers conclude. “It is clear the two species are largely separated across the metropolitan area.”
This is only a small study, but the team speculates that coyotes may be controlling the feral cat population throughout the Chicago area, keeping the cats out of the fragments of natural habitat that dot the suburbs. If the pattern holds in other areas, then in regions where coyotes can be found, the ecological impacts of cats (that is, the cats’ killing of birds and other native wildlife) might be overestimated. Cats have gained a reputation for being evil murderers that devastate wildlife, but we’re finding that the story is far more complicated. And its one that needs to be better elucidated.