Hibernates singly or in small clusters, usually several dozen or fewer. Most mating occurs from November-February, but many females are inseminated before hibernation begins. Sperm is stored until ovulation occurs in spring. Gestation lasts 56-100 days, depending on temperature, size of the hibernating cluster, and time in hibernation. Young are weaned in 6 wk and fly in 2.5-3 wk after birth.
Growth rate depends on temperature.
The maternity group begins to break up in August. Females mate in their first autumn, males in their first or second autumn. About half of young females return to their birth site after their first hibernation. Maximum recorded age is 16 yr. Forages with many other species.