Thriving under our noses, but stealthily: coyotes
and World Science staff
Scientists have long thought coyotes intently avoid cities, but a new study has found the opposite.
Groups of the historically maligned beasts are thriving in some large U.S. cities: they lurk in darkness and come out at night, probably helping the human inhabitants by eating vermin, the study found.
This animal’s amazing ability to thrive in cities has surprised scientists, said Stanley Gehrt of Ohio State University, who is studying coyotes in urban Chicago.
Since the study began six years ago, Gehrt and his colleagues say they have found that urban coyote populations are much larger than expected; that they live longer than their rural cousins in these environments; and that they are more active at night than coyotes living in rural areas.
Coyotes also do some good–they help control rapidly growing populations of Canada geese throughout North America, Gehrt said. And while his coyote research is concentrated in Chicago, he said, the results likely apply to most major metropolitan areas in North America.
The study began in Chicago in 2000 when Gehrt was a researcher for the Max McGraw Wildlife Foundation in Dundee, Ill. In the 1990s the foundation received growing complaints about coyotes taking pets and stalking children. In the late 1990s the Cook County Animal Control agency asked Gehrt to gather information on coyote populations in metropolitan Chicago.
The study was only supposed to last for a year.
“Nine million people live in the greater Chicago area,” said Gehrt. “We didn’t think very many coyotes could thrive in such a highly urbanized area. We also thought that the few animals that were causing problems were probably used to living around people.”
The problem with studying coyotes is that they’re very hard to catch, he explained. They quickly learn to avoid traps. But his team distributed their traps widely throughout the greater Chicago area and caught several animals. They put radio-tagged collars on them and released them.
The researchers had expected to find no more than several dozen coyotes, he said, but they were everywhere. “We couldn’t find an area in Chicago where there weren’t coyotes,” Gehrt said. “They’ve learned to exploit all parts of their landscape.”
By now, the researchers say they have caught and tagged more than 200 coyotes. They estimate that there may be somewhere between several hundred and 2,000 coyotes living in Chicago. Some inhabit parks; others live among apartment and commercial buildings and in industrial parks.
The funding agency, Cook County Animal Control and Conservation Medicine Coalition, renews the study every year because the researchers keep finding results that surprise them, Gehrt said. This spring, Gehrt will publish the first round of papers from the last six years’ worth of research.
The major findings include:
Coyotes are helping to curb the booming Canada goose population in urban areas by eating the eggs. Coyotes can clean out several goose nests in one night, but don’t actually eat all the eggs, Gehrt explained. Rather, they usually carry the eggs away from the nest and bury them, saving them for later, Gehrt said.
Coyotes prefer to hunt alone, but often form packs to defend territories. Gehrt estimates that roughly half of urban coyotes live in territorial packs that consist of five to six adults and their pups born that year. These packs establish territories of about five to 10 square miles – a fraction of the area that a rural coyote pack would cover. Thus, the population densities in the urban area are usually three to six times higher than rural populations.
Those urban coyotes that don’t hunt in packs can cover ranges of 50 square miles or more, often in just one night. “The first solitary coyote we tracked covered five adjacent cities in a single night,” Gehrt said.
Urban coyotes survive far longer than their rural cousins. A coyote living in urban Chicago has a 60-percent chance of surviving for one year, while a rural coyote has a 30 percent chance of living for another year.
Most coyotes pose little threat to humans, Gehrt said. The problems generally start when people feed coyotes, even unintentionally. “A coyote may eat the food that’s left outside for a pet,” he explained. “It’s not uncommon to see a coyote pass through an urban or suburban neighborhood.
“But most coyotes aren’t thrilled about being seen by people,” he continued. “Urban coyotes are more active at night than their rural counterparts, so humans don’t see a lot of their activity. In many cases, coyotes are probably doing us favors that we don’t realize – they eat a lot of rodents and other animals that people don’t want around.”
The next phase of the study is underway, Gehrt said. He and his colleagues are conducting genetic study of coyotes’ social system. The researchers want to know if members of a pack are closely related. Such information could help to further explain coyote behavior.
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