An effort is under way to see bison hunted within Grand Canyon National Park. Arizona politicians who are pushing that proposal say the bison in the park are bison-cow hybrids that are "wreaking havoc" on the park.

The measure was expected to come up Thursday when the House Natural Resources Committee marks up legislation pertaining to the National Park Service. Seeking authorization to allow a bison hunt within Grand Canyon are U.S. Sens. John McClain and Jeff Flake and U.S. Rep. Paul Gosar, all three Republicans.

“The animals wreaking havoc on Grand Canyon National Park are no ordinary bison,” said Sens. McCain and Flake and Congressman Gosar back in March when they introduced their proposal. “They are cross-breeds between bison and cattle that continue to destroy the natural vegetation and pristine lands that make the park a national treasure and destination for millions of visitors. Our legislation advances a common-sense proposal that would cull these unmanageable herds and eliminate federal barriers by allowing volunteer hunters to take home the meat.”

Opposing the legislation is the National Parks Conservation Association, which said in a release that, "NPCA opposes Rep. Gosar's amendment to allow hunting of hybrid bison in Grand Canyon National Park. The National Park Service is currently preparing a Bison Management Plan and will soon make recommendations on the removal or management of the hybrid bison in the park—this amendment is premature."