Details of seasonal cycles and reproduction vary by species.
Many bats hibernate colonially in caves in winter, with the females entering hibernation first; then they disperse in spring, with females typically forming small to fairly large nursery colonies that may roost together in caves or in trees or a variety of other sheltered places. Most give birth in late spring to only one pup (some species may give birth to two, three, or even four). Usually, the mothers give birth while hanging by their feet; they curl their tail and wing membranes to catch the newborn pup, which begins nursing soon afterward. Bats are typically born naked or only slightly furred, and with their eyes closed.
Bat mothers are solicitous of their young, as they nurse and groom them, and are careful to relocate their own pups within the colony when they return from foraging excursions. The young usually begin to fly in midsummer.
Mating usually occurs in late summer or fall, as bats swarm near the entrances of their hibernation caves, but it can also occur during brief, active times during the winter and again in the spring. Bats typically undergo delayed fertilization: Females that mated in the fall or winter have the sperm within them go dormant, and the egg also pauses its development within the ovary. In spring when the female bat awakens, the egg is shed and fertilization occurs.
Lifespan varies with species; some can live to be more than 30 years old. This longevity reflects the low reproductive rate combined with low predation pressure.
Some bat species do not hibernate in the southern parts of their range, though they may hibernate in Missouri where winters are colder.
Some species, such as the silver-haired bat, eastern red bat, hoary bat, and evening bat, are migratory, moving south in the fall and north in the spring, sometimes flying great distances and in rather large numbers. These migratory bats may not spend much time in caves at all. In some cases, as in the evening bat, some individuals may migrate in fall to warmer climates while others stay in Missouri and hibernate.
Many bat species show a high fidelity to their home caves, returning to the same hibernating sites year after year, and finding their way back even when transported 180 miles away from the cave in which they were trapped.