Yellowstone Bison Plan Looks to Balance Interests

A new bison management plan is expected to modernize practices and largely reflect the way the icon of the West is currently managed in Yellowstone National Park.

The National Park Service recently released both its final environmental impact statement and record of decision to round out the National Environmental Policy Act process that began in 2022. The agency went with its “preferred alternative” in the plan, which will manage bison within a population range of 3,500 to 6,000 after calving, averaging 5,000.

“That is generally what the last 10-year average has been,” park Superintendent Cam Sholly told Mountain Journal in a July 25 interview. “From a population standpoint, we understand that more bison could be inside Yellowstone from a summer habitat capacity perspective, but we would have been irresponsible to not consider the winter habitat availability and the limited tolerance outside the park.”

As Sholly alluded to, Yellowstone bison and their management tend to split public opinion, especially in areas bordering the park.

Bison populations in the West have fluctuated since the 19th century. The ungulate was nearly hunted to extinction as white settlement expanded westward but over the past 50 years, populations have rebounded. So has residential and agricultural development outside the park. The combination has created more potential for conflict, especially for ranchers raising cattle susceptible to brucellosis, a disease that bison carry.

Brucellosis is a contagious disease that can cause abortions in pregnant bison, cattle and elk. According to the Animal and Plant Health Inspection Service, the disease has mostly been eliminated in cattle, though livestock and wild animals in Greater Yellowstone are occasionally infected. The agency notes that bison and elk are the last carriers of this disease in the U.S.

When the Interagency Bison Management Program was established in the 1990s, officials believed that bison were the primary risk of brucellosis transmission to cattle. And while it’s documented that roughly 60 percent of bison have brucellosis, research published since the last bison management plan was conceived in 2000 shows that there has been no documented transmission of the disease between bison and cattle. Instead, the main culprit of wild to domestic transmission is elk, according to the final environmental impact statement.

“Bison are the only species we constrain, primarily because of a lack of tolerance outside the park,” Sholly said. That tolerance, he added, has grown since the IBMP’s inception, which was also reflected in the updated management plan.

During winter and spring, bison are allowed to migrate from Yellowstone into tolerance areas in Montana adjacent to the park’s northern and western boundaries, where they are separated from livestock by distance or fences. Outside of these tolerance areas, bison can be hazed back inside the park or killed.

Sholly said that the tolerance zones have expanded since the first iteration of the bison management plan. “I think that’s one of [Montana’s] biggest contributions to a wild and free-ranging bison population, which is one of the major IBMP goals,” he said.

The Montana Stockgrowers Association has followed the plan’s development with a watchful eye. Raylee Honeycutt, the organization’s executive vice president, said that while they continue to review the lengthy documents, the Stockgrowers emphasize the importance of management tools, including population control, spring hazing, vaccination, culling, tribal hunting, and shipment to processing facilities.

Late last year, the association submitted its comments on the draft environmental impact statement that signaled dissatisfaction with the plan’s alternatives at the time, which are largely unchanged from the alternatives in the final EIS, including the one chosen by the Park Service.

“MSGA continues to express its concerns with the increase in the bison population as it is likely to increase bison migration out the park and the risk of brucellosis transmission to cattle and the limited forage availability in the park during winter for a growing herd size,” according to an October press release from the group. “The association is further concerned with the concept of limiting management tools as the population increases, leading to an exponential growth in bison numbers.”

The state of Montana, while it also has not yet commented on specific management prescriptions in the plan, expressed disappointment in early July about the NEPA process and the state’s lack of involvement in it, despite its cooperating agency status.

Montana Republican Gov. Greg Gianforte said the Park Service did not solicit meaningful input from the state throughout the process, and did not give officials enough time to meaningfully review and comment on the updated plan.

“YNP has avoided substantive collaborative discussions with the state’s scientists and technical advisors at every turn on this issue, offering meetings only when documents and decisions were fully cooked,” Gianforte wrote in a letter to the Interior Department after the final environmental impact statement was released. “Such behavior only leads the State to one conclusion: the alternative was chosen and the course pre-plotted before NEPA even started.”

In the state’s comments on the draft environmental impact statement, it called for lower population thresholds and noted that tolerance areas the plan is based on are at the state’s discretion, and that they could shrink.

During the NEPA process, the Greater Yellowstone Coalition, a conservation organization headquartered in Bozeman, criticized the state’s position on bison management, which the group said would “manage bison like livestock.”

The coalition, in its own participation in the NEPA process, aimed for a population range of 4,000 to 7,000, said Shana Drimal, senior wildlife conservation associate with GYC. While the range the Park Service landed on is slightly lower than the coalition had hoped, Drimal said she understands the science behind the decision.

During winter 2022-23, a heavy snowpack pushed bison out of the park earlier than normal, around November, she said. It was also a highpoint in the past century for the population, which numbered roughly 6,000 bison.

“What we learned after that winter was that that was about the maximum that the areas outside of the park could really handle in terms of numbers of bison being on the landscape, based on the potential for conflicts, the potential for bison to breach that tolerance area and try to move into Paradise Valley,” Drimal told Mountain Journal.

In all, she said the new plan is a step forward in bison management. Before the updated plan, the park managed for a population range of 3,500 to 5,000.

The lack of land available for bison signals a need for more habitat improvements to hold more bison in the future, Drimal continued. “This just goes to show that we have more work to do,” she said.

Other alternatives explored in the plan would have either maintained the status quo or gone further in bison population growth, eliminating capture and processing. The “no action” alternative would have maintained a range of 3,500 to 5,000 bison after calving. On the other side, the third alternative would have set a population range of 3,500 to 7,000, ceased bison shipments to slaughter and, instead, limit populations by public and tribal hunting. 

Conservation groups, including GYC, the Buffalo Field Campaign and the National Parks Conservation Association, among others, want the Park Service to move away from slaughter as a management method. As prescribed in the original bison management plan in 2000, Park Service personnel have captured bison near Yellowstone’s northern boundary during winter to reduce bison numbers and prevent movement outside of tolerance areas. Captured animals have been shipped to processing facilities or transferred to Native American tribes as part of the Bison Conservation Transfer Program.

Under the new management plan, the park will continue to support tribal harvest outside the park boundary, Sholly said. Tribes exercise treaty rights to harvest bison on unclaimed lands outside the park, including Blackfeet Nation, Confederated Salish and Kootenai, Confederated Tribes of the Umatilla Reservation, Crow, Nez Perce, Northern Arapaho, Shoshone-Bannock, and Yakama Nation.

Bison hunts are an important aspect of Native American culture: for thousands of years, tribes have hunted the animal for meat and used its hide to make clothing, its bones to make tools.

Jason Baldes, executive director of the Wind River Tribal Buffalo Initiative and a member of the Eastern Shoshone Tribe, said that as a keystone species, bison support organisms on the landscape, including plants, mammals, insects, birds and more.\

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