Carnivorous animals like coyotes, mountain lions and bears are quickly adapting to urban life, posing problems for city-dwellers.
Ecologists at a summit in Ohio agreed that wild animals are poised to inhabit cities in the near future.
According to CBS News, the scientists referred to the increasing number of coyotes that are living in cities, particularly those that have recently moved close to Chicago's O'Hare International Airport.
Their introduction will likely mean the arrival of even more dangerous animals, say researchers.
"Mountain lions are already living in the outskirts of Los Angeles, Denver, and other western cities," research leader Stanley Gehrt told Discovery News in an interview.
"Black bears are living in a variety of cities in the West and in the East. Wolves have yet to make a regular appearance, but they are getting closer. In Europe, there are urban brown bears that act much like raccoons over here."
Gehrt's team at Ohio State University is currently undertaking a study on urbanizing coyotes by placing collars on them to track their movements.
They found that increasing numbers of the animals were inhabiting urban areas.
According to NBC News, Gehrt said that their presence can be explained by - not unlike why humans move to cities - the ease of living in a city.
He said "they don't have to go far to find food and water. They're finding everything they need right there, in the suburbs of Chicago."
OurAmazingPlanet said that coyote pups even survive five times longer than their rural peers.