BOZEMAN, Mont. (AP) - A new study suggests hunters attract grizzlies, sometimes from Yellowstone National Park.

But mountain lions and elk tended to leave areas attracting hunters, mostly moving into Yellowstone. And wolves really didn't seem to care.

A group of carnivore researchers working in and around the park monitored radio-collared grizzlies, wolves and cougars in the park's northern range and in the Absaroka Beartooth Wilderness Area, just north of Yellowstone, to determine how the predators react to the presence of hunters.

"Grizzly bears shifted north of the boundary once hunting began," the researchers determined in looking at a small sampling of bears.

Cougars, however, tended to leave the wilderness and head for the park once large numbers of hunters arrived, possibly following elk herds that also head south.

"Our findings for grizzly bears were not unexpected," wrote the study's authors. The scientists included representatives of the National Park Service, U.S. Fish and Wildlife Service, U.S. Forest Service, Montana Department of Fish, Wildlife and Parks, Montana State University and the private research groups Wildlife Conservation Society and Beringia South.

The 10 scientists cited previous studies showing hunters leave behind as much as 500 tons of guts, bones and discarded meat every year in the greater Yellowstone area.

That much food is a big motivator for grizzly bears, especially since hunting season coincides with the hyperphagia, a sort of feeding frenzy that grizzly bears enter before they take to their dens in the late fall or winter.

Numbers of hunting-related grizzly bear mortalities increased in the Yellowstone area during the 1990s and nearly half the increase came during early season hunts in September, the researchers said. The situation, the added, "may be exacerbated by an increasing and expanding grizzly bear population."

There are as many as 70 hunting camps in the area when the season opens, and they act as magnets for grizzlies.

Their movements to hunting zones "were correlated with the opening of hunting season," the study says.

More than half of all grizzly deaths and human injuries occur during big-game hunting seasons, based on statistics compiled by the state fish and game agency, said Kevin Frey, an FWP bear specialist.