Effects of Bark Beetle Infestation on Chipmunks in Southeast Wyoming

Current climate warming is affecting the distribution, population dynamics, and phenology of many plants and animals. Mountain pine bark beetle (Dendroctonus ponderosae) populations erupted in recent years in the northern Rocky Mountains due to a measurable decline in winter severity. These beetle eruptions caused high mortality of trees in southeastern Wyoming. Such forest reduction may substantially increase encroachment rate of steppe vegetation on previously forested areas. Reduction in forest extent decreases habitat for many species of wildlife that rely on forests for food, shelter, and escape from predators. In this project, I assessed the abundance and diet of least chipmunks (Tamias minimus) in forest and sagebrush habitats as an indicator of the responses of other small mammals to forest loss. Using capture recapture methods, I found that chipmunk abundance was higher in both habitats in 2010 than in previous years and increased from early to late summer. This was more pronounce d in forested habitats. The difference in chipmunk abundance between the two habitats may be explained by food availability; I found significant differences in isotopic signatures of chipmunks and their food items between habitats. My results suggest that chipmunk populations may be negatively affected by future forest losses.