ALBANY, N.Y. - Black bears are multiplying and on the move across North America, snooping around cities where they've been a rarity, becoming roadkill and leading states to start or expand hunting seasons.

When bears come into contact with humans, they usually create just a nuisance by raiding garbage, bird feeders, orchards, crops, and beehives - or by simply scaring the daylights out of residents.

But as bears enter more urban areas, the number of highway accidents has also increased, creating a danger for drivers usually accustomed to slowing down just for deer.

Bear numbers across the Northeast are at or near record levels, said John McDonald Jr., a wildlife research specialist with the U.S. Fish and Wildlife Service based in Massachusetts.

"For the first couple weeks of June, males will be looking for females and last year's cubs will leave their mothers and head off in random directions trying to find their own home range," McDonald said.

A bear may wander 100 miles or more looking for a new home, he said.

The bear population in the United States rose from about 156,000 in 1989 to about 227,000 in 2001, according to a report published by McDonald in 2007.

New York state has about 6,000 to 7,500 black bears, according to the Department of Environmental Conservation.

The state used to have three distinct populations of bears - in the Adirondack Mountains, in the Catskills, and in the southwestern corner of the state. Over the last decade, those populations have expanded toward one another, and bears are wandering into areas where they've rarely been seen.

Two bears - a yearling and a 300-pound adult - were killed recently on highways around Buffalo.

Two bears were spotted in recent weeks wandering through Philadelphia's suburbs, forcing lockdowns at several elementary schools. One bear was bowled over by a car, but both bear and driver went on their way.

In New York, the number of bears killed by vehicles annually has increased from 14 to 61 over the last 20 years. In Pennsylvania, there are about 200 bear-vehicle collisions a year.

That compares with about 50,000 deer-vehicle collisions a year in New York and nearly 100,000 a year in Pennsylvania, McDonald said.

Lynn Rogers, founder of the nonprofit North American Bear Center in Ely, Minn., estimates there are about 900,000 black bears across North America. The number of bears in Minnesota has grown from fewer than 6,000 to more than 22,000 in the four decades he has been studying them, he said.

"Bears are more abundant now than they have been in hundreds of years," said McDonald, who completed doctoral research on bears. "They're filling in states like Ohio and Kentucky that historically didn't have bears for hundreds of years."

Rogers, who has spent 42 years observing bears in their habitat, attributes the rise in black bear population to conversion of farmland to forest and to the fact that the animals are no longer poisoned, trapped, or shot as vermin.

Conflicts arise when people enter bear habitat, or vice versa.

"There are bears that take up residence in suburban areas and lose their fear of people," McDonald said. "Problems range from destroying bird feeders to breaking into people's homes."