Use and selection of winter hibernacula by the eastern pipistrelle (Pipistrellus subflavus) in Texas

To determine characteristics associated with winter hibernacula of the eastern pipistrelle (Pipistrellus subflavus), microclimate parameters, land-use, and densities of bats were recorded and compared among 4 study sites, associated with box culverts under Interstate Highway 45 in Texas. Presence of bats in hibernacula varied throughout the year. Selection of winter hibernacula in temperate regions may not be dependent on microclimate parameters alone. Minimum temperature was the only significant microclimate predictor of abundance of bats and reflected seasonal use of hibernacula during winter. Analyses of land-use data revealed a significant correlation between number of bats present at each roost and amount of agriculture and forest surrounding each site. Distance from the opening of the culvert to forest also was correlated with number of bats. Occupancy of hibernacula by the eastern pipistrelle was greatest for December and January, with males consistently appearing in higher ratios than females. Fidelity of bats to hibernacula was highly variable within and between seasons. Recaptures ranged from 14 to 73% during both seasons with 24% of the bats marked during the Ist season returning the following year.