HELENA, Mont. (AP) _ Bison that wander outside Yellowstone Park to graze in Montana, where they're considered a threat to livestock, can be shot by park rangers as well as state game wardens, the National Park Service said.

Also Monday, the 9th U.S. Circuit Court of Appeals said it would hear arguments in Seattle in early March on an appeal by the Fund for Animals, a national animal-rights group that seeks to stop the killing.

The court, however, refused to stop the shooting while the appeal is pending.

State officials believe the bison spread brucellosis, a disease that can cause domestic cows to miscarry.

Wardens have shot 150 bison so far this winter out of an estimated 3,500 in the park herds. The herds are growing by about 500 animals a year.

The job fell to state game wardens after the Montana Legislature last year ended the practice of allowing hunters to kill the animals.

In a decision Monday, the National Park Service agreed to participate in an interim plan under which park rangers will, at the state's request, assist in killing bison that wander out of the park onto private land in Montana.

The national director of the Fund for Animals, Wayne Pacelle, charged that the Montana state veterinarian, Donald P. Ferlicka, was ''ludicrously exaggerating'' the threat that bison pose in transmitting brucellosis disease to cattle.

''It appears that the state kills bison at the request of any complaining rancher,'' Pacelle said in a letter to park Superintendent Bob Barbee. ''This would be comical if its result was not so tragic.''

Ranchers have ''deeply imbued cultural prejudices'' toward bison and Ferlicka is fanning those prejudices, Pacelle said.

Ferlicka insisted that the killing of bison was scientifically justified. Most of the bison killed outside Yellowstone have been tested for brucellosis and 38 percent tested positive, he said.