The life cycle of a bat

By Ethan Farley, 2021 3rd Year BSc (Hons) Ecology and Environment Science, University of Gloucestershire.

Winter

During the winter months, bats in Britain tend to be hibernating during this period (Historic England, 2021). They become dormant to conserve energy, reduce their body temperature and movements, to stay alive over the winter months. Bats will either roost on their own or in small groups. They will choose to hibernate in undisturbed areas such as abandoned buildings, tree holes or caves. However, bats cannot remain like this for too long as their fat reserves will not keep them going indefinitely.

Spring

As winter draws to a close, bats begin to feel the warmer temperatures. Their bodies tell them it is time to start feeding again, as their fat reserves are running low. Feeding of moths and other flies will begin over the nights, though early spring is still a cold period, with bats returning to roost during bad weather (The Bat Conservation Trust, 2021). Female bats in late spring will look for suitable sites to give birth and will join with other female bats to form what they call maternity colonies. This gives them a warm, safe environment to give birth to their pups. Warm, dry loft spaces are ideal for bat nurseries, so it’s always important to check these places before building work on your house can go ahead.

Summer

As summer springs into action, mother bats will give birth to their pups in their maternity colonies (Nagorsen and Brigham, 1993). Mothers feed their pups milk and cradle them using their wings while they are too small (less than an inch) and weak to forage for themselves. However, in three to five weeks, the pups will begin flying for themselves, often dropped to the floor to encourage flight. Thus, as pups can now forage for themselves, maternity colonies disperse, and both female and male bats look for mating roosts.

Autumn

Males in autumn compete for the best roosts to attract a female bat to mate with, though the males will also use calls. In most species, male bats will seek multiple females to breed during the autumn period (Altringham, 2011). As temperatures begin to drop, increased feeding during the night occurs to build up fat stores for the coming winter months. After mating has taken place, the bat couple will leave one another to locate the best location for hibernation. Cooler temperatures are encouraging them to become dormant once again.

References:

• Altringham, J.D (2011). Bats: From Evolution to conservation. 2nd ed. London: Oxford University Press. pg105.
• Bat Conservation trust. (2021). A year in the life of a bat. Available: https://www.bats.org.uk/about-bats/a-year-in-the-life-of-a-bat. Last accessed 1st July 2021.
• Historic England. (2021). British Bats and Their Life Cycles. Available: https://historicengland.org.uk/advice/technical-advice/buildings/building-works-and-bats/british-bats-and-their-life-cycles/. Last accessed 1st July 2021.
• Nagorsen, D.W.; Brigham, R.M. (1993). Bats of British Columbia. London: UBC Press. p17.