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

Currently, Shiras moose (Alces alces shirasi) herds in the state are exhibiting a wide range of population performance, with many declining (e.g. Jackson, Snowy Range, North Park, CO) and some stable (e.g. Sublette, Unita) or increasing (e/g. Bighorn). For the declining herds, potential mechanisms that may affect carrying capacity are habitat deterioration due to current and historic overbrowsing, regional variation in forage quality, and other disturbances, such as severe wildfire or bark beetle outbreaks. Additionally, a new and growing predator community is present in the northwest corner of the state and may prevent higher recruitment rates form being achieved, but these predators can not account for declines elsewhere in Wyoming, Colorado, and Utah. Further, a newly emergent disease, the carotid artery worm (Elaeophora schneideri), appears to be prevalent in Wyoming. Unfortunately we do not yet understand the impacts of this disease on the nutritional condition and survival of moose. In combination with the observed range in population performance, variability of moose habitat in the state represents a timely opportunity to evaluate habitat-performance relationships (i.e. local carrying capacities). Such a statewide habitat evaluation could serve as a benchmark to understand the relationship between moose habitat and population performance and would provide the WGFD with 'early warning' metrics to predict where and when declines are likely to occur, and would improve the scientific basis of moose population objectives.