Day roost characteristics of northern long-eared bats (Myotis septentrionalis) in relation to female reproductive status

In summer, females of most temperate bat species aggregate at maternity roosts, during which time females gestate, give birth, and wean offspring. These activities make the presence of suitable roosts critical for population persistence. Many studies have identified important roost tree characteristics by comparing roost trees to random trees. However, if bats select trees that facilitate either torpor use or maintenance of normothermic body temperatures relative to the energetic demands of reproduction, then it follows that roost tree characteristics may vary similarly. We compared variation in roost tree and site selection by lactating northern long-eared bats to the pre- and post-lactation periods. Scores from 2 principal components were the best predictors of the variation in roost selection. Relative to pre- and post-lactation periods lactating bat roost sites had a high and relatively open dominant canopy with low tree density (both coniferous and deciduous) and roost sites were situated high in tall trees. Our result demonstrates that when managing for bat roost trees, within-season variation in roost tree use should be considered.