Bats generally start to come out of hibernation in early spring. Some bats begin emerging in March, and by April, most bats are active again. However, if temperatures drop, they may temporarily return to a state of torpor. By mid- May, when temperatures are consistently warmer, all bats are usually fully active and out of hibernation. When bats first come out of hibernation, they are very hungry because they have survived the winter on fat reserves and typically lose about half their body weight during this period. Female bats then prepare for maternity season, giving birth to pups typically in May or June. In summary:
- Early emergence: March
- Most active and consistently out: April to mid-May
- Maternity preparation and birth: May to June
This pattern can vary slightly by species and region but generally holds for many bats in the U.S. and similar climates.
