Introduction

Landscapes of western North America have been highly dissected by glaciation, vulcanization, physiographic heterogeneity, and the formation of major river systems. These physical features have served as barriers to movement and gene flow among mammal populations resulting in speciation throughout evolutionary history. As a result of these many influences and resulting speciation, the mammal fauna of this area is highly rich and diverse. About half of the mammalian species in North America occur in western coniferous forests (see Lawlor 2003). Although fewer species are found specifically within these forests, most are widespread in many vegetative communities.

Mammalian faunas of coniferous forests of western North America represent many taxonomic groups, and they perform many functional roles. Shrews are little known but are often the most abundant species in these forests, and they are primarily insectivorous, as are bats. In contrast, ungulates are highly visible and represent large amounts of standing biomass in forested ecosystems. Their browsing and herbivorous diets can have a major influence on plant communities and other species of mammals.

Direct associations between coarse woody debris and mammals vary among species and studies, but most information on this association is for the terrestrial small mammals. For many species, coarse wood debris serves as an important form of cover or as feeding sites (McComb 2003). For example, martens use downed logs as important hunting sites during the winter when snow is deep.