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Animal Health

Bruc plan completed for Wyo bison

Written by Christy Hemken
Jackson - The Wyoming Game and Fish Department (WGFD) has completed Brucellosis Management Action Plans (BMAPs) for two bison herds in the state’s northwest corner.
    Following the lead of other BMAPs for elk and cattle, these plans outline what livestock producers and wildlife managers can do to reduce brucellosis risk and transmission among wildlife and from wildlife to livestock.
    “In contrast to the BMAPs for elk herds, in the bison plans we listed four actions we’re going to pursue, rather than options we’re going to look into,” says Brucellosis Information and Education Specialist Chris Colligan.
    The first action is to reduce the population of Wyoming bison herds to herd objective, which is 500 animals. “The second is to maintain habitat,” says Colligan. “Any opportunity to improve habitat – specifically winter range – will spread the animals out.”
    Last season the WGFD allowed a much higher bison harvest than in the past, partly because of permits allowed on the National Elk Refuge. “We increased permits for bison in an attempt to bring the herd down to the population objective,” says Colligan.
    The third action is to minimize the risk of transmission from bison to cattle through separation of the two. “In the past we’ve hazed animals that were getting close to domestic livestock operations,” says Colligan. “We’ve also used hunters to provide a disturbance or to remove animals.”
    Lastly, the WGFD is considering vaccinating the bison herds. “At this time that action is not going to be effective, and we’re going to wait for the development of a more efficacious vaccine,” he says, adding that vaccine delivery mechanisms also need to be improved.
    The National Park Service (NPS) has been vaccinating bison within Yellowstone Park, and Colligan says the WGFD will wait to see how that goes, then improve on the techniques used there. “We’re going to wait for the best science to become available before we begin vaccination,” he says.
    Colligan says Wyoming’s bison have historically had a high sero-prevalence. “Brucellosis has been documented in herds within Yellowstone and Wyoming, although we haven’t documented any cases of transmission from bison to cattle,” he says, explaining that bison don’t interact with cattle as freely as elk.
    “Most bison in the Jackson area are supplementally fed throughout the winter so they remain concentrated in the National Elk Refuge,” he says. “The bison coming out of Yellowstone to the Absaroka herd units are typically only bulls, with very few cows coming out of the Park to the east, and transmission risk is greater from the cows.”
    According to the WGFD, an average of 64 percent of male bison test positive for the disease, while females test an average of 59 percent positive.
    For cattle grazing in Grand Teton National Park, Colligan says the NPS has developed a grazing system to ensure separation of cattle and bison in both spatial and temporal aspects. Brucellosis vaccination is also required for cattle grazing in that park.
    The bison plans were the last two BMAPs completed by the WGFD through cooperation with land management agencies and livestock producers. In Dec. 2007 public comments were taken in Cody and Jackson regarding the management plans.
    “The more people we can get to read the plans, the better,” says Colligan. “It’s important they see how the Game and Fish is trying to work with producers.”
    To view the plans, visit http://gf.state.wy.us/wildlife/Brucellosis/index.asp. Christy Hemken is assistant editor of the Wyoming Livestock Roundup and can be reached at This email address is being protected from spambots. You need JavaScript enabled to view it..