Individuals wintering in cold climates hibernate, but may be active on warm winter days. Migrates between summer and winter ranges, probably over long distances. During spring and fall, large groups are encountered, occasionally in unusual locations. Females precede males in the northward spring migration, which occurs from February-May. Fall migration occurs from September-November.
Copulation occurs in autumn, in migration or on the wintering grounds.
Mating is followed by delayed fertilization. The young are born from mid-May through early July. From 1-4 young may be born, but most litters have 2. The offspring are capable of flight after 33 days. Forages with many other bat species.