A professor of wildlife ecology at Ohio State University says urban coyotes, the largest of the mid-size carnivores, may be setting the stage for their larger brethren to start migrating to cities.
"They're the ones that are kind of pushing the envelope right now," Stan Gehrt said, suggesting animals like bears, wolves and mountain lions may be next.
"It used to be rural areas where we would have this challenge of co-existence versus conflict with carnivores," said Gehrt, who gave a talk on the topic Friday at a conference in Columbus, Ohio.
"In the future, and I would say currently, it's cities where we're going to have this intersection between people and carnivores."
In an interview earlier this week, Gehrt suggested cities probably evolved because it was safer for people to live in mass settlements. When people lived in a dispersed fashion "we were prey," he said.
But that freedom from predation also works to the advantage of wild animals, which are pushing into cities in huge numbers. Gehrt described Toronto's raccoon population, for instance, as "humongous" — a description no Torontonian would argue with.
While pet owners and home owners in cities have been tussling with skunks and raccoons for years, coyotes have recently made appearances in urban centres far from the open range with which people associate them. "They don't have any predators in the cities," he explained.
Greater Chicago, with a population of nine million people, is home to at least 2,000 coyotes, said Gehrt, who has been studying the animals in Chicago for the past 12 years. "That's minimum. That's a really conservative estimate," he said.
He and colleagues even found a pack of coyotes living about eight kilometres from O'Hare International Airport, one of the world's busiest airports. The animals live in the smallest coyote territory ever observed, less than a third of a mile.
As the animals have lived at the site for years, the environment must be meeting all their needs, Gehrt said, adding that what scientists are learning about urban coyotes defies much of what was thought about the animals in the past.
Canadian cities and towns are seeing coyotes with increasing frequency as well. Calgary has a large population of the animals; some people estimate as many as 600 to 700 live in the city.
They are also seen in Saskatoon, said Dr. Emily Jenkins a professor in the University of Saskatchewan's department of veterinary microbiology and school of public health.
While those cities might not seem so far off the beaten track for the animals, Toronto certainly is — and yet coyotes are seen in the city from time to time. And recently in New Waterford, N.S., wildlife officials killed four of the animals after a teen girl was attacked by a coyote.
Why are carnivores encroaching on urban centres? Gehrt said the reasons are complex, and may differ from species to species.
The ranks of coyotes has swelled in recent years, with fewer people hunting and trapping the animals. But the animals are territorial and can only tolerate so many members in a pack. When numbers get too large, young males are expelled and have to find new territory for themselves, Gehrt said. In some cases, cities have filled that need.
Jenkins said the easy access to garbage is also a draw for some carnivores, such as bears. "They're just big raccoons," Gehrt agreed.
The plentiful supply of raccoons and the occasional house pet may be a draw for mountain lions, which don't eat garbage, he said.
With new animals may come new health challenges for people. Jenkins has been involved in research tracking the presence of a dangerous tapeworm in urban coyotes, Echinococcus multilocularis.
But Gehrt noted that if larger carnivores prey on urban raccoons, the risk from raccoon roundworm might actually decline.
Jenkins didn't necessarily agree that coyotes would serve as ice-breakers for larger carnivores.
But she suggested the design of cities may be drawing the animals into closer contact with people, with ravines and green belts and river valleys acting as virtual highways for animals trying to traverse territories fragmented by urban sprawl.
"It's not uncommon to hear about cougars and moose coming through town because they've just sort of naturally funnelled into the river valley and then pop out at a really bad place — like 8th Street in the middle of Saskatoon, which we've had happen," she said.
"It goes both ways. Are we in their territory? Are they in our territory? It's kind of a moot point when we all just have to figure out if we're going to co-exist or if we're going to try and fight these battles as we traditionally have with bullets and trapping and poison."
Municipal planners need to keep these kinds of issues in mind and should consult with wildlife ecologists, Jenkins said.
Gehrt said it is difficult to predict how this convergence of cities and wildlife will turn out.
"Basically it's an uncontrolled experiment that's going," he said. "It's hard to say for sure exactly what's going to happen."