Caretakers of the more than 5,000 bison, commonly called buffalo, which are living in Yellowstone National Park, have reached an agreement to reduce the herd by up to 900 animals in a wildlife management move designed to lower the risk of spreading brucellosis to cattle. It is a destructive and dangerous bacterial disease according to the Centers for Disease Control and the US Department of Agriculture.
Although the spread from bison to cattle has not been documented, authorities are concerned because the disease can spread to other animals, wild and domestic including elk and dogs. Fewer than 1,000 people a year get brucellosis (called undulant fever when it strikes people) but it can be contracted by eating undercooked meat, consuming unpasteurized dairy products, contact with skin lesions and even, very rarely, by breathing in the germs. In humans, the disease can cause fever, muscle fatigue, joint pain and other symptoms which may linger and recur. In cattle it is a great concern because it causes abortions and other negative health outcomes.
The agreement calls for the slaughter, hunting or quarantine of 600 to 900 animals. The move should reduce the herd slightly but it is expected to recover during calving season. Culling herds is common and is practiced by many private herd owners and some Native American tribes.
Federal, state and tribal authorities have all signed off on the deal, which is part of an ongoing drive to expand the bison population after its brush with extinction at the end of the 19th century. At one point bison numbered an estimated 60 million and roamed as far east as Pennsylvania and north into Canada. There are two closely related types of bison, plains bison and wood bison. Very closely related, the plains bison inhabited the Great Plains and their cousins were mostly found in Canada. Both types of bison were hunted to near extinction by the 1880’s with about 1,000 animals left out of the millions alive a few decades before. Since 1900 the numbers have increased greatly. About 20,000 wild plains bison exist today and about 11,000 wood bison. In total there as many as 500,000 bison scattered across the western United States and Canada. Most are in private hands and many show some genetic crossbreeding with domestic cattle. A number of the herds are owned by native tribes including the Crow, the Blackfeet and the Sioux. The Rosebud Sioux are developing a herd they wish to be the largest of all the Native American herds in existence.
The Yellowstone herd is of particular importance because it is descended directly from bison who have never left the park area. They are genetically purebred and have not crossed with cattle.
Culling is part of the herd management strategy as bison can overpopulate the land they live on. Bison meat was a mainstay of Native American diets and has gained popularity with other diners because it is low fat and grass fed.