Effects of brush piles on small mammal abundance and survival in central Pennsylvania

Brush piles have long been promoted as a means to enhance wildlife habitat, yet few studies have experimentally tested the perceived benefits of these structures for wildlife or evaluated the efficacy of different arrangements of these piles within landscapes. During summers 2005 and 2006, we used a mark-recapture study to compare small mammal abundance and survival in forested habitats provisioned with brush piles vs. similar habitats without, both at sites located adjacent to agricultural edges and within the interior of forests in central Pennsylvania. Northern short- tailed shrews Blarina brevicauda, mice Peromyscus, and eastern chipmunks Tamias striatus were all frequently captured within brush piles at edge and interior sites. Peromyscus were significantly more abundant at edge vs. interior sites. The presence of brush piles, however, seemed to have little effect on small mammal abundance or survival with the only potential effect being an increased overwinter survival rate experienced by Peromyscus at brush pile sites. We hypothesize that although brush piles provide cover and foraging sites for small mammals, the large quantities of coarse woody debris that exist naturally in many forested systems may already adequately provide these habitat features, minimizing the effects of brush piles on small mammal population dynamics.