Credit: Stan Gehrt; Flash module photo on hompage: background photo by GreyArea, doctored by Maggie Wittlin
The owners of the Chicago Bears might want to consider a new mascot for their team. The city is pretty much bear-free—save the local zoo—but there is at least one pack of coyotes living right downtown in the Loop, and there may be thousands of coyotes residing in the Chicagoland area.
"I'm sure there are some areas in the most heavily-developed core that have few, if any, coyotes," said Stan Gehrt, a wildlife biologist at Ohio State University. "However, we can't find any of those areas."
A six-year study into the habits and habitats of urban coyotes, sponsored by Cook County's Department of Animal Control and led by Gehrt, has continually produced surprising results. When the study began, Gehrt's team expected to find the canines confined to large parks or forest preserves. Coyotes are hard to catch and the researchers' initial sample was limited; if the study had ended after a year, researchers might not have observed the coyoytes' full range. "Once we began putting radio collars on these coyotes," Gehrt said, "they taught us very quickly that we had to expand our vision of what is suitable habitat for coyotes."
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Scientists believed that, given the pressures of living amid the nine-million people of greater Chicago, coyotes would not be able to maintain defined territories or preserve the complex social structure of the packs they typically live in. "But they do," said Gehrt. "And it looks no different in an urban area than it would out in the country. They carved out territories in completely developed areas."
Coyotes are commonly feared or seen as a nuisance. However, the Cook County project shows that coyotes control more typical nuisance species, such as rats and mice. "People don't realize the ecological benefits that coyotes have," said another urban coyote researcher, Jonathan Way,s who recently received his Ph.D. from Boston College. "They make other animals act more naturally."
For instance, coyotes facilitate population control by eating the eggs of Canadian geese. Chicago's goose population, which had been expanding at 10% to 20% per year, is now growing at just 1% to 2%, due to coyote predation. Likewise, around Chicago, coyotes are the major predator of white-tailed deer. When deer become numerous, they over-browse the foliage, fawns become more visible, and predation rates rise until the deer population drops and their cover is restored.
"A lot of people assume urban coyotes are eating garbage or pets, and not anything else." Ohio State's Gehrt said, "We found 99% of their diet has nothing whatsoever to do with people, even though they are living among people every day. The majority, by far, will walk right by garbage cans. They prefer to catch their own prey."
Coyotes' diets shift through the year, according to availability; Gehrt found that fruit is among the top four sources of food, along with mice or rats, rabbits and deer.
Way, who has been studying coyotes in urbanized parts of Massachusetts since 1998, calls most resident urban coyotes "low-key animals." To succeed in cities, coyotes must learn to be invisible, avoiding peopled areas where they are likely to be spotted. Urban coyotes are more active at night than their rural counterparts; Way's studies have shown that coyotes cover 15 to 25 km (10 to 15 mi) a night as they range through a roughly 26-square-kilometer (10-square-mile) territory.