Bat boxes as alternative roosts for displaced bat maternity colonies

Maternity colonies of big brown (Eptesicus fuscus) and little brown (Myotis lucifugus) bats are vulnerable to exclusion from buildings. We monitored the use of bat boxes as alternative roosts for displaced colonies at 15 sites in Pennsylvania. Colonies returned to building roosts when exclusion attempts were inadequate. When successfully excluded, colonies moved to bat boxes that received ≥ 7 hours of direct sunlight and were attached to the building that formerly housed the colony. Preferred bat boxes offered high temperatures (8-10°C > ambient), an internal temperature gradient, and were wide enough (76 cm) to enable many bats to roost side by side. Our results suggest that bat boxes of the proper design and placement can serve as important tools in managing nuisance or displaced bat maternity colonies.