Brilliant Bats!

28th September 2023

Bats are the only mammals on the planet capable of powered flight, and they can navigate through the darkest night by the power of echolocation. Across the globe they are vital pollinators, valuable pest-controllers and even effective tree-planters. There are 1,300 different species worldwide and they can be found almost everywhere but the frozen north and south poles.

Here in the UK there are 18 different species of bat and all of them have been recorded in Sussex. Sadly, many of our bat species are rare and the rarest of all is the Greater Mouse-eared Bat. Since 2002, Sussex has been home to the only UK population: a single individual who faithfully roosts in the same secret location every winter. He was nicknamed the loneliest bat in Britain and was almost certainly the last of his kind living here – until the exciting discovery in January this year of a second individual hibernating in the same system of underground tunnels. Happily, the Greater Mouse-eared Bat is now less lonely and slightly less rare but still our largest resident bat species, with a wingspan of 45 cm – about the same as a Starling.

Greater Mouse-eared Bat © Ryan Greaves

At the other end of the spectrum are the commonest bat species, the Pipistrelles, which are so tiny they can fit inside a matchbox. Pipistrelles can be seen in gardens, parks and urban greenspaces where they are sometimes mistaken for small birds flitting about at dusk. They first leave their roosts about twenty minutes after sunset, flying fast, low, and seemingly erratically as they zig-zag after their insect prey.

Common Pipistrelle Bat © Hugh Clark FRPS

Despite their diminutive size, Pipistrelles have a healthy appetite and will each devour 3,000 flies, midges, and mosquitoes in a single night, catching and eating their food on the wing. If you were to listen in with a bat detector, you’d discover that some Pipistrelles emit their rapid-fire echolocation calls at a much higher frequency, which distinguishes the Common Pipistrelle from the higher-pitched Soprano Pipistrelle.

Like all our bat species, Pipistrelles rely on flying insects but as the bounty of the summer months diminishes and autumn shifts towards winter, food is harder to come by and bats prepare to hibernate. Pipistrelles are small enough to tuck themselves into tiny cracks and crevices in trees or buildings, where they often go completely unnoticed until they emerge in spring - the secret stars of the night sky.

Charlotte Owen
Conservation Officer at the Sussex Wildlife Trust