Most bats will mate in their second year. Some do not breed at all until they are seven to ten years old. They mate and give birth once a year usually to a single young. Twins and even triplets have been known but are rare. Compare this to a mouse which might produce 90 young a year and it is clear why bats are the rarer species. Gestation takes between 45 and 90 days but tracking bat mating is so difficult the precise timings remain something of a mystery. Bats can live up to 30 years but the risk of bat life mean average life expectancy is far lower at between four and five years. Female bats emerge from hibernation to find nursery roosts around about April which are shared with other females and very few males. The births take place in the usual hanging position but the females are able to create a pouch with their tail membranes to catch the young as they emerge. The umbilical cord has also been known to act as a sort of maternal bungee cord preventing the tiny new born bat from plummeting to the ground.
