BILLINGS, Mont. (AP) -- State Department of Livestock crews spent much of Tuesday hazing about 500 bison into Yellowstone National Park.

It was the largest hazing operation so far this year.

The bison had wandered out of the park's western border. About 65 of them were on airport property at West Yellowstone, and another 35 were in a nearby parking lot, said Rob Tierney of the Livestock Department.

Others were scattered on private land and elsewhere.

The hazing of wandering bison is allowed under a state-federal management plan aimed at reducing the potential spread of brucellosis from bison to cattle in Montana. Many of the park's bison have brucellosis, as do some elk in the region, and the disease can cause cows to abort.

Opponents of hazing have said bison deserve more tolerance when they leave the park.

Last year, more than 1,000 bison were captured, and most were sent to slaughter.

So far this year, few bison have strayed from the park. Mild weather has allowed most of the animals to find food inside the park, thereby reducing their migration.