Little Brown Bats Utilize Multiple Maternity Roosts Within Foraging Areas: Implications for Identifying Summer Habitat

Abstract

Abstract Identifying habitat features that may influence the survival and fitness of threatened species is often constrained by a lack of information about the appropriate scale for habitat conservation efforts. Canada's Species at Risk Act lists little brown bats Myotis lucifugus as Endangered and there is a need to determine the scale for delineating important summer habitat features that should be protected. We used a 19-y dataset of banded little brown bats in a 15,000-km2 area of southern Yukon, Canada, to examine fidelity to roost sites and potential foraging areas. We captured and banded 4,349 bats during 208 live-trapping sessions at maternity roosts. Adult females used multiple roosts during the maternity period, separated by up to 6.1 km, within foraging areas, to which individuals exhibited fidelity. Our fidelity rates (≤ 60.5%) are the lowest, and roost-switching rates (≤ 35.5%) the greatest, reported for little brown bats. A small percentage (14.0–20.7%) of females banded as juveniles returned to their natal roosts or foraging areas as adults. We infrequently observed long-distance (25–200 km) switching to novel foraging areas (< 1% of banded bats). We established bat houses to mitigate the loss of a cabin roost; 46.3% of the bats banded at the cabin occupied these houses. The longest documented period of roost fidelity was 18 y, by a female banded as an adult. Roost fidelity by returning adult females declined annually by 3.8–5.3% due to natural mortality, roost switching, or dispersal. Having a choice of multiple maternity roosts within a foraging area may permit little brown bats to select optimal microclimatic conditions throughout the maternity season. Given that fidelity to foraging areas may be higher than to specific roost sites for little brown bats, identification of summer habitat based on foraging areas may be a more effective conservation strategy than relying solely on roost sites.