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The Montana Cooperative Wildlife Research Unit

The University of Montana

Sarah Sells - M.Sc. Candidate - Wildlife Biology

Advisor - Mike Mitchell


Natural Science Building - Room 312

Phone: 406-243-4348



B.S.: Fisheries and Wildlife Science at Oregon State University, 2005

Broadly, my interests are in wildlife conservation and disease. Since 2004, I have worked with a variety of fascinating species in dramatic surroundings, including Olympic marmots in Washington’s Olympic National Park, small mammals in Honduran cloud forest, Sage Grouse in Wyoming, and Burrowing Owls in California. I moved to Zion National Park in southern Utah in 2007 where I worked with many taxa.  One of my major interests in Zion was the iconic bighorn sheep. Extirpated in Zion by the 1950's, they were successfully reintroduced through immense management efforts; yet, any herd’s future is uncertain due to the ever-present threat of disease.


Proactive management of pneumonia epizootics in bighorn sheep in Montana

Disease outbreaks in bighorn sheep provide an excellent example of the potential severity and long-term implications of disease on the conservation and management of a species.  In particular, pneumonia epizootics have greatly impacted bighorn sheep, with new die-offs reported in the West every year.  Once pneumonia pathogens are introduced to a population of bighorn sheep, initial all-age mortality can exceed 80%.  The pathogens may also become endemic, resulting in pneumonia outbreaks that can cycle for decades.  Of critical concern, lamb recruitment often remains chronically low for many years following an epizootic, which further threatens a herd's long-term persistence, particularily if pre-epizootic abundance was low, mortality rates were high, or other stochastic events occur that push the herd to extinction.  Herds may require extensive management to recover, including removal of diseased individuals, augmentation from other herds, or reintroductions.  Despite great outlays of time and expense in attempt to restore herds after a pneumonia epizootic, they may never fully recover.  Disease management is therefore a major concern for wildlife agencies.  Disease management is usually reactive, however, as few tools exist to aid proactive management of wildlife diseases.

This project will provide a case study for developing risk and decision models for proactive wildlife disease management. My objectives are to:
  1. Collect data on past pneumonia epizootics in bighorn sheep in Montana from records and through collaboration with Montana Fish, Wildlife and Parks biologists.
  2. Develop a risk model to predict risk of future pneumonia epizootics based on assessment of past epizootics in Montana.
  3. Develop a decision model using a structured decision making process for identifying appropriate proactive management actions based on probability of pneumonia, herd-specific objectives, and predicted consequences of management actions.

Project Status, 2014:

We successfully developed a risk model for pneumonia in bighorn sheep in Montana based on analysis of data from 43 herds from 1979-2013.  We presented preliminary results at the Montana Chapter TWS meeting in early 2014, and are working on finalizing and publishing results.  We are working with biologists and managers from Montana Fish, Wildlife and Parks this summer to develop the decision model.

Natural Sciences Room 205

Missoula, MT 59812