National Park Service U.S. Department of the Interior Yellowstone Center for Resources Yellowstone National Park BRUCELLOSIS SCIENCE REVIEW WORKSHOP PANELISTS’ REPORT 2013 Panel participants: (left to right) Merete Aanes, Mary Ellen Wolfe, Michael Miller, Vanessa Ezenwa, Peter Nara, Steve Olsen, John Cox, Terry Kreeger, Anna Jolles, Keith Aune, Dave Hallac, Pat Flowers 2013 Brucellosis in Yellowstone Bison Science Review & Workshop FEBRUARY 26-28, 2013 u CHICO HOT SPRINGS RESORT u PRAY, MT Financial support for the workshop was provided by the Yellowstone Park Foundation and the National Park Service. Credits for photos: Where not otherwise indicated, photos are courtesy of the National Park Service. BACKGROUND inside Yellowstone National Park using a rifle-delivered biodegradable bullet with a vaccine payload revealed many The bison population that resides in Yellowstone uncertainties that would likely limit a significant reduction National Park is chronically infected with brucellosis (Bru- in disease prevalence and could have unintended adverse ef- cella abortus), which may induce abortions or the birth of fects on bison. non-viable calves and can be transmitted between bison, The National Park Service and Montana Fish, Wild- elk, and cattle. In most years, bison will migrate to low el- life & Parks remain committed to the suppression of bru- evation habitat outside the park boundaries in Montana to cellosis in a manner that is aligned with bison conservation. search for forage during winter and spring, where they could In light of limited and sometimes conflicting information on potentially come into contact with cattle. The risk of brucel- “best” prospective approaches for managing brucellosis in losis transmission from bison to cattle under current con- free-ranging bison, however, these agencies sought an inde- ditions appears to be low yet tangible, and is understand- pendent evaluation of current scientific knowledge and as- ably of concern because such transmission could result in sessment of suggested management approaches. economic loss to livestock producers from slaughtering in- fected animals, increased disease testing requirements, and decreased marketability of their cattle. This risk has reduced APPROACH To this end, a team of experts that do not work di- tolerance for bison in the greater Yellowstone ecosystem and elsewhere—thereby impeding the conservation of plains rectly on the issue of brucellosis in Yellowstone bison (Ap- bison. Therefore, the primary issue motivating discussions pendix A) were invited to a workshop to review and evaluate about brucellosis reduction in Yellowstone bison center on the current science and integrate that science into feasible the risk of brucellosis transmission to cattle in Montana. disease management approaches that consider the inter- ests of all stakeholders. David Hallac (Yellowstone National ISSUE & NEED Park) and Pat Flowers (Montana Fish, Wildlife & Parks) were appointed to serve as co-chairs on the panel, with the Bison and elk in the Greater Yellowstone Ecosystem role of helping lead discussions among the eight panelists. have long been infected with brucellosis. The management The facilitated workshop was held at Chico Hot of this disease has been a contentious issue for decades, es- Springs Resort in Pray, Montana, on February 26-28, 2013. pecially for Yellowstone bison. In years when bison migrate On the first day, presentations were provided to workshop to low elevation habitat outside Yellowstone National Park panelists that communicated the perspectives of stakehold- in Montana to search for forage during winter and spring, ers and the relevant science regarding host ecology, brucel- there is a small but tangible risk of brucellosis transmission losis dynamics, and disease management practices; panelists from bison to cattle, which could result in economic loss to also reviewed and considered other published materials in local livestock producers. the course of formulating their recommendations (Appen- In 2000, the federal government and the State of dix B). Panelists spent the second and third days addressing Montana agreed to a bison management plan that estab- specific questions based on the information presented and lished guidelines for cooperatively managing the risk of bru- developing their recommendations, with deliberations con- cellosis transmission from bison to cattle. This Interagency cluding mid-day on February 28. The entire workshop was Bison Management Plan (IBMP) emphasized maintenance open to the public. Although the public did not participate of a wild, free-ranging bison population while protecting in the panelists’ discussions, members of the public did have the livestock economy in Montana. To date, no documented opportunities to offer comments to the panel at the end of transmission of brucellosis from Yellowstone bison to cattle each day of the workshop. (Appendix C) has occurred. This success appears due, at least in part, to The panelists were charged with evaluating current successful efforts by federal and state agencies to maintain brucellosis science and providing consensus-based conclu- separation between cattle and bison. However, management sions and recommendations in a brief report to be finalized interventions that have removed large numbers of bison after the workshop. The panelists were also asked to limit yielded neither a measurable decrease in brucellosis expo- their discussions and recommendations to the current areas sure or infection rates within the bison population nor an of the IBMP and management practices within those areas. appreciable change in perceptions about the risk of trans- Specifically, the sponsors requested focused attention on: mission to cattle. Consequently, management has empha- sized spatial-temporal separation of cattle and bison, which • the state of and efficacy of ongoing brucellosis suppres- has thus far successfully prevented brucellosis transmission sion activities between these species. • the feasibility of significantly suppressing the disease in Vaccination of bison has been proposed as the bison primary method for reducing the level of brucellosis infec- • the likelihood that disease suppression will result in tion. Because few eligible bison (calves, yearlings) migrate more tolerance for bison and advance bison conserva- to boundary capture facilities during most winters, little tion progress has been made on the vaccination efforts envi- • the potential impacts of disease suppression on bison sioned in the bison management plan. Furthermore, a re- conservation, ecology and wildlife viewing in the park; cent evaluation of whether to vaccinate free-ranging bison • the pros and cons of implementing operational vaccina- 1 February 2013 • 2013 1 tion programs, to include hand vaccination at capture cine that could be delivered more practically), but we are not facilities and remote vaccination (i.e., without capture) aware of any such advances becoming available to manag- • a recommended course of action regarding research ers in the foreseeable future. To date, adaptive management and development to suppress brucellosis in bison. of contact between cattle and bison in the IBMP area ap- pears to have effectively prevented interspecies transmis- A workshop charter described the purpose, clari- sion of brucellosis. Spatial-temporal separation of these two fied the responsibilities and authority of various partici- species has effectively precluded such transmission despite pants, described the role of the public, and proposed a deci- relatively high seroprevalence in bison. Consequently, sero- sion making process with preliminary ground rules to guide prevalence in bison does not seem to be a good predictor of the process. brucellosis transmission risk from bison to cattle under the The panel arrived at their conclusions and recom- present management plan. It appears reasonable to assume mendations by consensus. In this context, consensus was that reducing seroprevalence through vaccination (or some defined as a general agreement or outcome of a group deci- other means) would have an effect on the risk of brucellosis sion-making process that most participants could live with. transmission among bison, but no experimental field data Though the group strove for unanimity, they retained the exist to support that assumption. option of choosing to settle for an agreement that had sup- On the potential ecological impacts of remote port of almost all members. vaccination: In addition to the foregoing main conclusion The organizers’ intent was that conclusions and rec- that an aggressive remote vaccination campaign for free- ommendations from the panel would be considered by the ranging bison cannot be justified based on available data, National Park Service in decision-making on the potential we also discussed other potential collateral consequences of implementation of future vaccination programs, and that such a program. Our distilled summary of this discussion is the workshop report also would inform short- and long- as follows: term adaptive management decisions on and strategies for disease management activities associated with the IBMP. In- • We anticipate that remote vaccination would have be- formation provided by the panel and presenters also may be havioral impacts on bison (e.g., reduced tolerance of used in the development of future bison management plans. people, vehicles, etc.). • Reduced tolerance for humans and vehicles could lead CONSENSUS PANEL CONCLUSIONS to shifts