Bats truly are amazing creatures. From their skillful flying to hunting prey using echolocation, bats have abilities that humans can only dream of. Perhaps one of their most impressive talents is surviving harsh winters by hibernating.
Although tropical bat species almost never hibernate, as they have a plentiful supply of food all year long, those in colder climates build up fat stores and find hibernation sites in the autumn. They usually hibernate from November to March – though they may not fully awaken until May. During these months, insects are harder to find, so it's more efficient for bats to stay still, rather than expending energy on hunting.
Bats manage to survive by drastically changing their body temperature, breathing rate, metabolism, and heart rate. Amazingly, a bat's heart rate can drop from 1,000 beats per minute to as low as 20 or even 10 bpm. By the end of the hibernation period, a bat may have lost around half of its body weight.
- Female bats usually give birth to a single pup in June. Over the next few months, they will live on their mother's milk, learn to fly, and gradually start to catch insects. By the end of the summer, young bats have moved on, ready for the mating season during September and October. At the same time, bats finish building up fat reserves and look for suitable hibernation spots.
- Bats aren't entirely inactive during the winter. They may sometimes leave their roost on warmer nights if they need to find food and water. This may also happen if they are disturbed – but they are likely to go back to sleep. Yet even in the spring, when hibernation is finished, they can go into a state of torpor during cold spells.
- Although some bats roost in caves during the winter, they are more likely to be found in holes in old trees, or even man-made structures like walls, roofs, or barns. To help bats in your area have a successful hibernation period, consider installing a well-insulated bat box on a tree, balcony, or roof in a sheltered yet sunny spot, ideally around 13 - 16 feet (4-5 m) off the ground.