The National Park Service is looking at using sharpshooters, capture and other methods to reduce the number of bison that are roaming the far northern reaches of the Grand Canyon and damaging resources, officials said.
The massive animals can weigh up to 2,000 pounds, and park officials say they are destroying water sources, vegetation, soil and archaeological sites. Hunting is prohibited within park boundaries, but the agency has the authority to kill animals that harm resources, using park staff or volunteer hunters.
The park service announced in 2014 that it would work on a long-term plan to manage bison and do a more in-depth environmental review. But the Grand Canyon said last week that it changed course because immediate action is needed to control the growing bison population.
Park officials are asking the public for comment. Reduction of the animals could start this winter if everything goes as planned. Between 80 and 200 bison are sustainable, not the 400 to 600 now living on about 310 square miles, officials said.
"We're considering a suite of tools," Sue Consolo-Murphy, acting chief of science and resource management, said Friday. "Until we get into this, we don't know what's going to work."
Identical bills in the U.S. House and Senate would let state-licensed hunters kill the bison and keep the meat. Arizona Sen. John McCain and Rep. Paul Gosar touted them as a cost-saving measure and criticized the park service for what they see as delayed action.
"We can't afford to allow more devastation to be caused to the park while the park service twiddles their thumbs trying to come up with an expensive plan," Gosar said in a statement. "We have a plan, and it puts Arizona hunters to work doing what they love, accomplishing this important task for free."
Consolo-Murphy said using volunteers is not out of the question, and the park is looking at models in other places for shrinking wildlife populations. Typically, the animal meat is turned over to wildlife agencies, tribes or charities to distribute.
Anything passed by Congress would have to be integrated into the park's plan.
Bison were introduced to the area in the early 1900s as part of a ranching operation to cross-breed them with cattle, creating hybrids known as "beefalo" or "cattalo." The animals no longer look like cattle but have a small percentage of cattle, if any, in their genes.
Opportunities for hunters to kill them on nearby U.S. Forest Service land have diminished because the bison spend more time in the boundaries of Grand Canyon National Park. Hunting permits for bison are the most sought-after of the state's hunted big-game species.
Birth control and relocating bison have not been effective in keeping them out of the park, officials have said.