Big brown bats are documented across Pennsylvania in records centered on open water with nearby roosting cover. Pymatuning’s coves, Presque Isle’s Lake Erie setting, and the wooded Delaware corridor each combine insect-hunting space with trees or buildings that can shelter bats by day.
The record set rises from June through August, when warm nights make both bats and observers more active outdoors. Winter records confirm that the data are not limited to summer, and the seasonal crest describes detection, not the size of Pennsylvania’s apparently secure S4 population.
Full species profile
