North Rim bison herd to be culled near Grand Canyon National Park

Lethal, non-lethal methods to be used to drop herd numbers below 200

The bison herd, originally brought to Arizona in 1906, has wandered far from its first home at House Rock Wildlife Area and now spends most of its time in the park.


The bison herd, originally brought to Arizona in 1906, has wandered far from its first home at House Rock Wildlife Area and now spends most of its time in the park.

GRAND CANYON, Ariz. — The National Park Service (NPS) will work with cooperating agencies and partners to reduce the size of the bison herd on the north rim of Grand Canyon National Park (Park).

The herd is approximately 400 to 600 animals and will be reduced over the next three to five years to fewer than 200 by lethal culling utilizing skilled volunteers and non-lethal capture and transfer to cooperating agencies and tribes.

NPS prepared an Initial Bison Herd Reduction Environmental Assessment (EA) which evaluated management actions that would reduce the herd. NPS Intermountain Regional Director Sue Masica signed a Finding of No Significant Impact (FONSI) authorizing the park to proceed with the selected action which is designed to quickly reduce bison population density. 

Given the current distribution, abundance, density, and the expected growth of this herd, the NPS is concerned about increased impacts on park resources such as water, vegetation, soils, archaeological sites, and values such as visitor experience and wilderness character. Reducing the herd size will protect park resources and values. 

NPS biologists estimate that the herd has grown from approximately 100 bison, brought to the House Rock Wildlife Area in the early 1900s, to between 400 to 600 bison. Though the bison roam the Kaibab Plateau, they spend most of their time on the north rim of the park. Biologists predict that the herd could grow to nearly 800 in the next three years and be as large as 1200 to 1500 animals within 10 years without further management actions to control the size of the herd.

Multiple agencies are involved with bison management on the Kaibab Plateau and this EA was prepared in collaboration with the Arizona Game and Fish Department, the U.S. Forest Service, the Bureau of Land Management, and the InterTribal Buffalo Council. Partner organization goals and objectives for bison management were considered in development of the EA and the park and partner organizations are now actively developing specific operational guidelines for herd reduction. An announcement of opportunities and a process for tribal members and members of the public to participate in volunteer culling will be made once operational guidelines for herd reduction are in place.

The EA, FONSI and other reference documents can be found on the NPS Planning Environment and Public Comment (PEPC) website at


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