Bat roosts in buildings and trees provide critical shelter for hibernation and maternity colonies — disturbance during these periods causes bat mortality and offspring abandonment with serious welfare consequences.
Bat roost disturbance has concentrated welfare impacts at critical periods. Disturbance of maternity colonies in June-August causes mother bats to flee, abandoning dependent pups that cannot yet fly or thermoregulate. Pups die from exposure and starvation within hours. Hibernation disturbance forces bats to arouse from torpor — each arousal event costs 30 days of stored fat and may leave animals unable to survive until spring. The welfare harm from a single renovation project can kill dozens of bats through well-intentioned but mistimed work.