While Yellowstone bison are not considered either endangered or threatened, they are one of the last remnants of the wild plains bison. Due to concerns from farmers and Montana agribusiness, the bison populating Yellowstone National Park are kept at a level of approximately 3,500 animals. This is done by periodically culling the herds, mostly by slaughter. A small percentage of the animals are shipped to research facilities as opposed to the slaughterhouse. Since the wild bison in Yellowstone have been reduced by about 600 animals this year, officials are done killing them for now.
Whether the current reduction will be enough for Montana ranchers will be determined in the coming months. Officials have reported that this winter’s slaughter has reduced the bison by 522, with 264 of those kills coming from hunters. An additional 60 animals were relocated to a research facility to be used in experiments. The slaughter and capture program was legalized in 2000 through a court-mediated agreement. The agreement, signed by the governor of Montana, the U.S. Secretary of Agriculture, and the U.S. Secretary of the Interior, allows for Yellowstone wild bison populations to be limited to 3,000-3,500 head. Even after the recent killings, the bison herd remains at a population level of around 4,000. If they do not reenter official Yellowstone State Park grounds early enough, it is possible that more will be slaughtered in the spring.
Bison killing is now typically done in the winter months at Yellowstone National Park. It is during this season that the animals tend to wander outside of official park territories and therefore may be prone to the population management efforts. The efforts toward population management are conducted through the National Park Service as well as the Montana Department of Livestock, the Montana Department of Fish, Wildlife and Parks, and the U.S. Forest Service, among other agencies. These agencies work together to control the bison population under the Interagency Bison Management Plan.
The annual bison killing has long been controversial. Many Montana ranchers believe that the wild bison may transfer a disease called brucellosis to their cattle herds. The disease may cause cattle to abort spontaneously or become inflicted with arthritis or bursitis. While the possibility exists that this may transpire, there are no known cases where infection of domesticated cattle has occurred from exposure to wild bison. Environmentalists and wildlife advocates believe that, due to the probability that wild bison have developed immunities to brucellosis, the possibility of a transfer from the wild bison to the domesticated cattle is extremely unlikely. Ironically, the annual killing of bison may pose a greater hazard in brucellosis infections. Brucellosis is spread through bodily fluids and those hunters, veterinarians, and slaughterhouse workers may be not only exposing themselves to the disease but spreading it to the domesticated herds themselves.
Because the wild bison population still stands at approximately 4,000 animals, it is possible that the spring will see more hunters killing off more of these animals. The court agreement in place has population guideline limits of 3,000-3,500 bison which allows the possibility for up to another 1,000 of the wild herd to be culled. In the meantime, the remaining Yellowstone bison have been granted a reprieve as the killing, for now, is done.
By Dee Mueller