Historically, bison inhabited Jackson Hole, as evidence by the presence of prehistoric bison remains. These animals were extirpated outside Yellowstone National Park by the mid-1880s. In 1948, 20 bison from Yellowstone National Park were reintroduced to a 1,500-acre Jackson Hole Wildlife Park near Moran, WY. A population of 15-30 bison was maintained in a large enclosure there until 1963, when brucellosis was discovered in the herd. All the adult animals were destroyed, but four vaccinated yearlings and fine vaccinated calves were retained. Twelve certified brucellosis-free bison were added soon afterward. In 1968, the herd (then down to 11 animals) escaped from the confines of the wildlife park. A year later, the decision was made to allow them to range freely. In 1975, the small Jackson bison herd (then 18 animals) began wintering on the National Elk Refuge. The use of standing forage by bison on this winter range was viewed as natural behavior and was not discouraged by managers. In 1980, however, the bison began eating supplemental feed being provided for elk, and they have continued to do so every winter since.
The discovery of supplemental feed by bison has had several consequences, including a decline in winter mortality and an increase in the populations' growth rate. As the population grew, separating elk and bison on feedlines became increasingly difficult, and the bison are now fed more than a maintenance ration to reduce displacement of elk from feedlines.
Since 1990, the size of the bison herd averaged increases of 10% to 14% per year, despite the Wyoming Game & Fish Department's managed efforts to harvest bison outside the refuge and Grand Teton National Park since 1997. Concerns about the rapidly increasing bison herd included increased damage to habitats, competition with elk, increased risk of disease transmission, and costs of providing supplemental feed for bison. The refuge began an annul bison hunt program in 2007 as a management tool to control the size of the bison herd.
Most of the Jackson bison herd winters on the refuge but are in areas where they cannot be easily viewed by the public. During the summer, bison primarily use nonforested areas of grassland and sage-steppe in Grand Teton National Park. In spring and fall transitional periods, bison may be found throughout both summer and winter range.
Photos of bison can be found in the National Elk Refuge's photo gallery.
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Elk aren't the only species of wildlife you may see on the National Elk Refuge.