Managing Yellowstone’s Bison Herd

Bison playfully butting heads in the snow

An ongoing battle between Yellowstone’s wild bison herds and ranchers that border the park has been going on for decades. Harsh winters in Yellowstone’s high country drive bison to more moderate-temperature low lands outside the park in Montana. Every year hundreds of Yellowstone National Park bison are shot and aggressively chased by helicopters and ATVs back into the park to prevent disease transmission to domestic cattle herds in Montana.

Ranchers are concerned about disease which can be spread by bison, elk and other wildlife. This has been the main focus of discussions. However there is also a fear of bison competing with cattle for grass on public lands which ranchers have enjoyed at a low cost. To add to the complexity of the situation, local Native Americans claim that Montana’s bison management plan infringes on treaty hunting rights. Historically, regional tribes hunt bison every winter. (See related story: Yellowstone Bison Hunt Takes Record Numbers)

The video below, “Silencing the Thunder,” shows many sides of the story.

Silencing the Thunder from Forest Clay Productions on Vimeo.

Shorter version of “Silencing the Thunder” on YouTube

February, 2014: This February, 20 wild bison from Yellowstone have been transferred to a Montana Native American tribe for harvesting. Another five were transferred to the U.S. Department of  Agriculture for use in a contraception program. This is in accordance with a multiyear plan to reduce the herd from about 4,600 to 3,000. Up to 600 bison could be killed this winter.

The last time a major reduction of herd was implemented was in 2008, when 1,600 were killed.

Janurary, 2013: Biologists in Yellowstone National Park recommend that 450 bison be killed this winter in order to “reduce abundance and growth potential,” reported Wyoming’s Star Tribune.

Estimates from 2012 report that Yellowstone has roughly 4,200 bison. These animals are divided into two herds: the central herd that stays primarily near Old Faithful and the Firehole and Madison river drainages, and the northern herd that gathers near the Lamar Valley and Yellowstone River drainage. Currently, the central herd has about 1,600 animals, while the northern herd has 2,600 animals, the most it’s ever had, according to park officials.

Ideally, the park service would like to see each herd have roughly 1,500 bison, with an equal number of males and females.

“Hunting and management removals of approximately 400 bison per year would provide a high certainty of approaching all desired conditions within five years,” reads the Interagency Bison Management Plan statement.

Without thinning the herds this winter, biologists say that there’s a 50 percent chance of bison numbers rising to more than 4,875 entering into the 2014 winter.

Those against the culling strategy argue that bison should be allowed in a larger area, rather than slaughtering the animals. Dan Brister, executive director of the Buffalo Field Campaign, a conservation group, supports enlarging the bisons’ habitat.

“We’d like to see them treat bison more like elk are treated,” he told the Tribune. “There’s a lot of great habitat they’re being excluded from.”

December 22, 2011: Montana Governor Brian Schweitzer is arguing with the U.S. Federal government over what to do with the upcoming winter’s overflow of hungry–and potentially brucellosis* exposed–Yellowstone National Park bison. TheAssociated Press reported that Interior Secretary Ken Salazar is proposing to move the bison to South Dakota’s Pine Ridge Indian Reservation and Great Sand Dunes National Park in Colorado. Gov. Schweitzer is adamant that the bison belong to the state of Montana and stay in Montana; he proposes moving them to the National Bison Range in the western part of the state and is blocking all shipments of fish and wildlife out of the state. The Department of the Interior believes transferring the bison to the National Bison Range will “stigmatize” the existing herd, although all bison slated for transfer have been found to be free of brucellosis. An alternate to transferring the bison is slaughtering them as has happened in years past. The projected number of bison expected to leave the park in search of food this winter is 1,000. Read the full AP article.

January, 2011: Limited food supplies within Yellowstone National Park in winter months leave hungry bison with little choice but to migrate to lower elevations not blanketed in snow. While park officials have made serious efforts to keep the animals from leaving the park, they have had little success. This year the roaming bison are being herded to holding pens at the Stephens Creek facility inside Yellowstone and, for the first time, the Brogan Bison facility at Corwin Springs. In total over 500 bison are currently being held at the two facilities.

Much of the controversy surrounding the wandering Yellowstone bison boils down to a disease some, not all, of the animals carry–*brucellosis, a bacterial infection that can cause cattle to miscarry, and is transferable between several species of animal. Ranchers have good reason to keep their cattle away from bison and other infected animals (elk can also carry the disease)–once a population becomes infected the cost to ranchers becomes immense (due to testing and slaughter expenses) and Montana ranchers are intent on maintaining their brucellosis-free standing.

In the past, as the Yellowstone holding pens reached capacity officials have been left with little choice but to send some bison to slaughter, a move that angered many, including Montana Governor Brian Schweitzer. Schweitzer recently passed a 90-day halt on the slaughter of Yellowstone bison.  The bill allows for enough time to herd bison back into the park come May 15, after the so-called “green-up” when the snow is melted and grass sprouts.

Currently incoming bison are sorted into infected and non-infected pens at the Stephens Creek facility. Some of the disease-free bison are then transferred to the Brogan facility; come spring the healthy bison will be returned to the park. A decision has not been made about the fate of the infected bison following the 90-day reprieve.

The holding pens, while an improvement over mass slaughter, are not a long-term solution for corralling hungry, wild bison. Montana lawmakers and the federal government have been working on a solution for years although previous agreements have yet to come to fruition.


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