Elk Contact Patterns and Potential Disease Transmission

Authors

  • Paul C. Cross U.S. Geological Survey, Northern Rocky Mountain Science Center, Bozeman, Montana 59715
  • Tyler G. Creech Oregon State University, Department of Fisheries and Wildlife, Corvallis, Oregon 97331
  • Michael R. Ebinger Institute on Ecosystems, Montana State University, Bozeman, Montana 59717
  • Kezia Manlove Pennsylvania State University, Department of Biology, Huck Institutes of the Life Sciences, University Park, Pennsylvania 16802
  • Kathryn Irvine U.S. Geological Survey, Northern Rocky Mountain Science Center, Bozeman, Montana 59715
  • John Henningsen University of Wyoming, Wyoming State Veterinary Laboratory, Laramie, Wyoming 82070
  • Jared Rogerson Wyoming Game and Fish Department, Pinedale, Wyoming 82941
  • Brandon M. Scurlock Wyoming Game and Fish Department, Wyoming 82941
  • Scott Creel Montana State University, Department of Ecology, Bozeman, Montana 59717

Abstract

Understanding the drivers of contact rates among individuals is critical to understanding disease dynamics and implementing targeted control measures. We studied the interaction patterns of 149 female elk (Cervus elaphus) distributed across five different regions of western Wyoming over three years, defining a contact as an approach within one body length (~2m). Using hierarchical models that account for correlations within individuals, pairs and groups, we found that pairwise contact rates within a group declined by a factor of three as group sizes increased 30-fold. Meanwhile, per capita contact rates increased with group size due to the increasing number of potential pairs. We found similar patterns for the duration of contacts. Supplemental feeding of elk had a limited impact on pairwise interaction rates and durations, but increased per capita rates more than two times higher. Variation in contact patterns were driven more by environmental factors such as group size than either individual or pairwise differences. Female elk in this region fall between the expectation of contact rates that linearly increase with group size (as assumed by pseudo-mass action models of disease transmission) or are constant with changes in group size (as assumed by frequency dependent transmission models). Our statistical approach decomposes the variation in contact rate into individual, dyadic, and environmental effects, which provides insight into those factors that are important for effective disease control programs.

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Published

2013-12-31

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Section

Montana Chapter of The Wildlife Society [Abstracts]