Seasonal differences in day-roost selection by Northern long-eared bats (Myotis septentrionalis) in Louisiana and a meta-analytical comparison across North America

Resting-site selection involves some of the most important decisions made by organisms. For forest-dwelling bats, where to roost influences not only resting but also many other activities that affect fitness such as raising young, thermoregulation, communication, and evasion of predators. Across much of North America, many bats roost in trees during summer and hibernate in caves during winter and as such, most of the focus on roosting ecology and forest management has been during summer. Along much of the Atlantic and Gulf coastal plains in the southern portion of North America, winters are relatively warm, few caves exist, and many bat species are active. Herein, we described the tree-roosting ecology of Northern long-eared bats (Myotis septentrionalis) in Louisiana in both summer and winter, examined roost selection, compared selection seasonally, and compared various aspects of roosting ecology in Louisiana to other areas across North America. We found that in Louisiana M. septentrionalis roosted primarily in pine trees and found no significant differences in roosting characteristics between sexes. Year-round, bats preferred roosts in trees in more advanced stages of decay than available trees. In summer, bats selected for plot level characteristics such as higher density of trees that were large and in more advanced stages of decay. In contrast, in winter, bats selected for tree characteristics such as those with taller, greater diameter and with more exfoliating bark. Comparisons with 21 other studies across North America indicated variation in selected roost characteristics among regions. These results highlight variability in roost selection through space and time and suggest that management strategies that are tailored to specific sites may be most effective for enhancing roosting opportunities of M. septentrionalis and ultimately the conservation of this species.