Long eared bats are mature at 12 - 15 months old. The long eared bat mates in the autumn, but the females are able to delay fertilisation of their eggs until spring. Females often form colonies in summer, with as many as 30 pregnant females roosting together.
They give birth to a single offspring, or very rarely, twins. Bat pups are born from late June to July and are completely hairless. The have long feet which they use to cling on to their mother’s fur. For the first 3 weeks, they stay with their mothers, feeding on her milk and then they are left alone in the roost while their mother hunts for food. The pups become independent after six weeks and are able to start hunting for themselves.