Cooperative Fish and Wildlife Research Units Program: Wyoming
Education, Research and Technical Assistance for Managing Our Natural Resources

Historically, elk pregnancy rates have not been a focus of study and management, but recent observations of unusually low pregnancy rates in several key Rocky Mountain elk herds have highlighted the potential importance of this demographic rate to calf recruitment. Yet the underlying causes of depressed elk pregnancy are poorly understood, which complicates the management of elk, their habitat, and their predators. A number of previous studies indicate that elk pregnancy rates are determined primarily by summer habitat conditions. It is also possible that winter severity influences elk pregnancy rates. Several recent studies have suggested that the risk of wolf predation depresses elk pregnancy, though there are currently conflicting results on this factor. Additionally, changes in age structure (i.e., following long-term recruitment declines), increasing brucellosis seroprevalence, and supplemental feeding may also influence elk pregnancy rates in Wyoming. Herein we propose a multi-population, regional-scale evaluation of variation elk pregnancy that is designed to help understand the relative contribution of each factor. This project is a collaboration of the Wyoming Cooperative Fish and Wildlife Research Unit (WCFWRU) and the Wyoming Game and Fish Department's Brucellosis Feedground Habitat group (WGFD-BFH).