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National Park Service releases bison management proposal for Yellowstone National Park

by Wyoming Livestock Roundup

National Park Service (NPS) proposes a major shift in its strategy for managing bison in Yellowstone National Park (YNP), which could mean larger herds, expanded hunting opportunities beyond park borders and more bison transfers to Tribal governments.

On June 6, the NPS released its final environmental impact statement (FEIS) for managing bison in YNP.

According to the NPS, the proposed plan allows the NPS to manage bison based on new scientific information and changed circumstances, explore ways to increase the transfer of bison to American Indian Tribes and continue working closely with Tribal Nations and agency partners in management.

“Managing bison is a balancing act between having enough bison to support a healthy population and some migrations out of the park, but not too large of a population that could lead to mass migrations and cause brucellosis transmission to livestock, harm people or damage private property,” NPS wrote on its website.

NPS notes the plan is committed to the YNP’s objectives of the Interagency Bison Management Plan (IBMP), which includes maintaining a wild, free-ranging bison population, reducing the risk of brucellosis transmission from bison to cattle, managing bison who leave YNP and enter Montana and maintaining Montana’s brucellosis-free status for domestic livestock.


The NPS’s FEIS considers alternatives to managing bison with varying population ranges and management activities.

Alternative One would continue management of bison pursuant to the existing IBMP, which was approved in 2000. 

NPS states, “This alternative maintains a population range between 3,500 to 5,000 bison after calving, similar to the last two decades.”

The plan allows for continued hunt-trap coordination, which balances population regulation in YNP by using harvest and hunting opportunities outside of the park.

It also allows for increasing the number of brucellosis-free bison relocating to Tribal lands via the Bison Conservation Transfer Program (BCTP) and work with the state of Montana to manage the already low risk of brucellosis spreading from bison to cattle. 

In Alternative Two, the preferred alternative, bison would be managed within a population range of about 3,500 to 6,000 animals after calving, with an emphasis on using the BCTP to restore bison to Tribal lands and Tribal treaty harvest and public hunting outside of the park to regulate numbers. 

In this plan, the NPS would shift away from transfer for processing as a primary population management tool and establish 5,200 bison in early winter as a population assurance threshold.

When there are more bison, NPS would manage for a decreasing population, where the post-calving population is smaller than the early winter population and would first rely on harvests to reduce numbers but would resume shipments for processing when necessary.

Under Alternative Three, NPS would rely on natural selection, bison dispersal and public and Tribal harvests in Montana as the primary tools to regulate numbers, which would likely range from 3,500 to 7,000 or more animals after calving.

The past and the future

Since 2013, bison numbers have ranged between 4,400 and 5,900 after calving, but numbers are likely to increase with less intrusive management. 

According to Park Services, research indicates there is sufficient forage in the park to sustain about 10,000 bison during summer months and 6,500 during the winter, although large variations in weather and grass production from year to year add complexity to this estimate. 

Near these estimates, foraging efficiency and bison condition should decrease, and more bison should migrate to lower-elevation areas in and outside of the park.

However, groups like the Montana Stockgrowers Association have long pushed to limit bison presence outside of the park, arguing risks associated with brucellosis transmission, fence damage and forage loss should preclude the park and other decision-makers from taking a more hands-off approach to bison management.

The park’s new plan preserves its ability to “take more aggressive management actions” in coordination with other federal, state and Tribal partners working under the existing IBMP if the risk of bison mingling with livestock increases.

In a press statement, National Parks Conservation Association Senior Yellowstone Program Manager Michelle Uberuaga describes the plan as an “important next step” which is science-based and will allow bison to thrive in Yellowstone.

“We applaud the park’s commitment to expanding Tribal cultural herds and will continue to work to ensure bison are managed in the same manner as other wildlife in the Greater Yellowstone Ecosystem, including ending the annual ship to slaughter program. The plan is grounded in the best available science and commits to flexible management strategies which will allow bison to thrive within Yellowstone,” states Uberuaga.

According to Montana Free Press, Gov. Greg Gianforte’s (R-MT) Press Secretary Katilin Price states, “The plan is not based in science, fails to incorporate any comments from our agency professionals and reflects a total disregard for the rulemaking process. In coming weeks, the governor will be submitting a formal response.”

The notice of availability of the FEIS was published in the Federal Register on June 7, initiating a required 30-day wait period.

At the conclusion of the wait period, NPS will sign and publish a record of decision, detailing the selected action.

Melissa Anderson is the editor of the Wyoming Livestock Roundup. Send comments on this article to

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