ISLAND PARK, Idaho (AP) - Officials plan to trap more grizzly bears in eastern Idaho's Island Park this summer and fit them with radio collars to get a better understanding of how many grizzlies are in the area and where they roam.

The Interagency Grizzly Bear Study Team, which includes members from the U.S. Fish and Wildlife Service and the Idaho Department of Fish and Game, trapped six grizzlies in Island Park last year and fitted them with radio collars.

"It will be interesting to see if we trap the same bears or different ones (this summer)," Lauri Hanauska-Brown, a wildlife biologist with the state fish and game department, told the Standard Journal in Rexburg.

Three of the bears trapped last year were released where they were captured, and three others were moved to more remote locations. Of the three relocated bears, one returned to Harriman State Park and was trapped again.

Keith Hobbs, the park's manager, said the number of bears trapped, along with signals from two other radio collars, indicate more bears are in the area.

U.S. Forest Service officials estimate the grizzly bear population in and around nearby Yellowstone National Park has increased from an estimated low of 136 in 1975, when the bears were listed as a threatened species, to more than 580 bears in 2004.

The grizzly population has been increasing 4 percent to 7 percent a year, officials estimate, causing bears to expand their range into areas where they have been absent for decades.

That's led Hanauska-Brown to try to educate Island Park residents about not leaving out items that might attract bears.

"Our biggest effort will be education in Island Park," she said. "We're going door to door to clean up problems. If we get an area cleaned up before the bears get there we'll have fewer problems. If a bear gets in the habit of getting into garbage, dog food or bird seed, it can become more aggressive about getting that food source."

Mark Orme, a Forest Service biologist for the Caribou-Targhee National Forest, said some summer residents in Island Park will also have to change their routines.

"We're pushing to show people there are grizzlies up there," he said. "People are going to have to go by the rules. In those summer home areas, people are going to have to keep garbage away from them."