Bat maternity roosts where females give birth and raise young are particularly sensitive to disturbance, with human activities during the June-August period causing pup mortality and roost abandonment.
Bat pups separated from their mothers during building works die rapidly from exposure and starvation — they require maternal milk and warmth for their first weeks. Even brief disturbance that causes roost abandonment can result in the death of all pups in a maternity colony. The vulnerability of roosting bats during the maternity season creates significant welfare obligations for property owners planning works.