Response of northern red-backed vole (Clethrionomys rutilus) populations to a major spruce beetle infestation in the Copper River Basin, Alaska

Abstract

A spruce bark beetle (Dendroctonus rufipennis) epidemic in the Copper Basin of Alaska beginning in the late 1980's has infested over 200,000 ha of white spruce forests in the region. The impact of spruce beetle-induced habitat changes on the northern red-backed vole (Clethrionomys rutilus) was investigated using mark/recapture techniques for 2 field seasons. Vole abundance and recruitment was significantly greater on low versus heavily infested sites but a large vole survival response was lacking. Vole food resources and protective vegetative cover did not vary substantially in areas with different levels of spruce mortality. Male movement distances were influenced by sex ratio, and females appeared to respond to food resources (epigeous sporocarps). Beetle infestations alone did not influence vole movements, but female movement distances decreased when heavy infestation levels were coupled with female age and sporocarp availability. The impact of beetle infestations on red-backed vole populations in the Copper Basin appears to be relatively small.