Characterizing Summer Roosts of Male Little Brown Myotis in Lodgepole Pine-Dominated Forests

Abstract

Although bat roosts have been well-studied in the eastern United States, we know less about roosts in the west. Western bats may make use of trees and snags, as in the east. However, the topography of the Rocky Mountains provides more exposed rock, and western bat species likely use different roosting features compared to the eastern US. Some western bats use rock features as autumn and winter roosts, but we know little about use as summer roosts. Additionally, roost studies often focus on maternity colonies, and information on roosts used by male bats is limited. Given that roosting sites may be limiting, we aimed to quantify characteristics of male roosts in lodgepole pine-dominated forests during the summer. We mist-netted for bats during summer 2017 and 2018 and attached transmitters to 34 male little brown myotis (Myotis lucifugus). We located at least 1 roost for 20 individuals (average = 1.6 roosts/bat; range = 1-5). Although snags were available, most bats roosted in rock features (15% in snags, 85% in rocks). Rock-roosting bats mainly used crevices (85%) instead of rock cavities (15%) and were more likely to select roosts with less canopy cover that were closer to water. They were also more likely to select roosts with wider entrances that provide access to a skyward-facing crevice. These results suggest that rock features may provide important summer habitat for male little brown myotis roosting in lodgepole-dominated forests. Understanding roost selection in these forests will help inform management decisions for conserving western bats