Year of Award


Document Type


Degree Type

Master of Science (MS)

Degree Name

Geography (Community and Environmental Planning Option)

Department or School/College

Department of Geography

Committee Chair

David Shively

Commitee Members

Jeffrey Gritzner, Martin Nie


bighorn sheep, disease, domestic sheep, Mannheimia haemolytica, Ovis canadensis, policy analysis, wildlife management


University of Montana


For over 100 years, disease has significantly limited bighorn sheep (Ovis canadensis) in the western U.S. Interaction with domestic sheep (Ovis aries) has been a primary cause of fatal bighorn disease (typically pneumonia), which has severely reduced or eliminated entire populations. Various wild-domestic sheep interaction policies exist to address the disease problem. In this analysis, six case study locations are compared and analyzed in an effort to evaluate policy efficacy. Locations examined and their bighorn die-off dates include: the Tobin Range, NV (1991); Aldrich Mountain, OR (1991); the Highland/Pioneer Mountains, MT (1994-1995); the Tarryall/Kenosha Mountains, CO (1997-2000); the Hays Canyon Range, NV (2007); and Bonner/West Riverside, MT (2010). Each location is investigated based on the policy analysis criteria of: buffer zones, herder supervision rules, trailing restrictions, consideration of domestic sheep presence prior to bighorn reintroduction, grazing allotment alteration efforts, education/negotiation attempts, fatal removal of bighorns near domestic sheep, coordination/tension between agencies, and funding difficulties. Regarding wild-domestic sheep interaction, all locations lacked clear buffer zones and trailing restrictions. At least five locations lacked funding difficulties. Where applicable, in four locations, domestic sheep presence was considered before reintroducing bighorns. In at least two locations, grazing allotment alteration was attempted, and bighorns were fatally removed. In at least five locations, agencies coordinated bighorn management, and negotiation or education was attempted. Tension between agencies existed in at least one location. From 1990-2010, the wild-domestic sheep disease issue gained prominence in policy documents, politics, and in the minds of agency biologists. This project’s case studies illustrate that bighorn-domestic sheep interaction policies can be successful with diligence, but success is unpredictable and location-dependent. If bighorns and domestic sheep are to coexist in the same areas, one size-fits-all separation policies covering the entire American West will not be effective. In a strictly ecological context, not allowing domestic sheep and bighorns to share the same ranges at all is the least risky and most effective way to prevent bighorn die-offs caused by domestic sheep disease.

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