Associations of bats with local structure and landscape features of forested stands in western Oregon and Washington

Abstract

Understanding the processes that underlie bat distribution and activity patterns requires examination of habitat associations at multiple scales. We examined the association of both local structure and landscape context with bat activity in forested stands using ultrasonic detectors. Forty-eight stands in western Oregon and Washington were monitored for bat activity on at least six occasions for each of two field seasons. At the stand level, bat activity was negatively associated with tree density. The standard deviation of tree density and the density of newly created snags were positively associated with bat activity. In combination, these three variables explained 46% of the total variance in bat activity among stands. Landscape-level variables did not explain any significant variation among a subset of stands (n=22). Our study suggests that management of forest-dwelling bats should focus primarily on structural attributes at the stand level and the effects of these features on feeding and roosting opportunities.