Bison Management

A hundred bison laying in a green field with a lush forest in the background and a sky full of clouds. Two NPS employees stand before the bison, counting the herd.
NPS and FWS employees count bison on the North Rim of Grand Canyon National Park. (S.Ciarrachi, 2017)

By 2025, the National Park Service will reduce the size of the overpopulated Kaibab Plateau (formerly House Rock) bison herd through live capture and transfer to American Indian Tribes and lethal removal with Skilled Volunteers. Grand Canyon National Park is reducing the size to under 200 in order to protect park resources—including vegetation, water, and sacred archeologic sites—from the impacts of the bison. Learn more about the effects of bison overpopulation on the impacts and monitoring website.

Bison Reduction to Date
As of September 2021, the park has held three successful live capture and relocation operations. A total of 124 bison have been transferred through the InterTribal Buffalo Council to 6 different Tribes in 4 different states. The park expects to continue yearly live capture and relocation until reduction goals are met. An additional 148 bison have been harvested off the park on the Kaibab National Forest during hunts managed by the Arizona Game and Fish Department. Other bison mortalities are also accounted for in this total (car-bison collisions, etc.).

A group of bison stand in front of a gate.
Bison enter a corral on the North Rim of Grand Canyon National Park during the park's bison corralling pilot program 2019.

NPS Photo/B. Maul

Population Size
The Kaibab Plateau herd moved from House Rock Valley into Grand Canyon National Park in the 1990's. In partnership with the U.S. Geological Survey, park biologists have outfitted bison with tracking collars to assist in annual population counts in order to determine whether or not reduction goals are being met. In addition, these tracking collars allow scientists to study the bison herd migratory patterns and population size. Visit the bison history page to learn more about the history of the herd.

Lethal removal with Skilled Volunteers will be piloted in Fall 2021. To augment live capture and relocation, twelve bison will be selected for removal by the NPS. Lethal removal will help achieve the management goal of quickly reducing the population while encouraging the herd to range more broadly on the landscape. This pilot program is being accomplished in consultation with Grand Canyon's Traditonally Associated Tribes. For more information, see our Frequently Asked Questions.

An operational summary report of bison management from 2018-2019 can be found in the 2018–2019 operations report.

The Environmental Assessment, Finding of No Significant Impact and other documents can be found on the NPS Planning Environment and Public Comment (PEPC) website.

If you have any specific questions related to bison management at Grand Canyon, please e-mail us.

Related information:

A sedated bison in a green meadow has a towel over her eyes while three park officials take her vitals.
Wildlife biologists at Grand Canyon National Park keep sedated bison stable during a collaring survey. (T.Corsetti, 2017)
Prepared by Desiree Espericueta, Wildlife Technician, Grand Canyon National Park (February 2018).

Last updated: September 22, 2021