20th January 2023

Greater mouse-eared bat population doubles - to 2! “This is a hugely important discovery”

Photo: ©Martyn Phillis greater mouse-eared bat

We are delighted to hear the good news that the population of Britain’s rarest mammal - the greater mouse-eared bat - has doubled from one known individual to two!

Since 2002, for 20 winters, one solo male bat was recorded hibernating in a tunnel near the south coast, by Sussex Bat Group.

He was nicknamed Britain’s loneliest old bat. Then he vanished and was feared lost. The pandemic prevented any monitoring from 2020 until now… However on January 14 2023, two greater mouse-eared bats were discovered in two disused underground railway tunnels.

The species had previously been declared extinct in Britain. Prior to that, a small population had been infrequently recorded in Sussex and Dorset but disappeared from Dorset in the early 1970s and finally from Sussex in 1992 - until this one individual turned up in 2002 and reappeared each winter.

The discovery is thanks to the important conservation efforts of volunteers who record bats as part of BCT’s annual National Bat Monitoring Programme. Sheila Wright of Sussex Bat Group said: “This is a hugely important discovery for us and demonstrates the importance of regular monitoring of bat colonies. We could have missed this highly significant find of the second greater mouse-eared bat in Britain. It also shows how important it is to safeguard these hibernation sites for bats.”

The greater mouse-eared bat Myotis myotis is the largest British bat at around 30g. It has been speculated that either one or both individuals may be migrating over the channel from France, to hibernate. England is on the far outer edge of their natural habitat range. The species is widespread in Europe, where populations are recovering from large historical declines in the latter half of last century, especially in north-west Europe. It likes large open roof spaces for its breeding colonies and it winters in underground tunnels and caves. It feeds on large insects from forest floors and grassland.

All British bat species are legally protected but populations face multiple pressures due to roost and habitat loss and habitat fragmentation. Therefore monitoring is vital to conservation work to help drive recovery.

The new discovery throws up exciting questions. Dr Stephanie Murphy, also of Sussex Bat Group, added: “There are now many questions for us to answer: is there already a small pioneer population of greater mouse-eared bats recolonising Sussex and we just don’t know where they are breeding, as in the case of the greater horseshoe bat, or, as a result of climate change and the hottest summers on record in the UK, are we getting greater mouse-eared bats just beginning to move over from mainland Europe to settle in the UK?”

Only time and more monitoring will tell….

To find out more about the Sussex Bat Group see: https://www.sussexbatgroup.org... of follow their Facebook page https://www.facebook.com/susse...

To find out more about the National Bat Monitoring Programme see: https://www.bats.org.uk/our-wo...

Photo: ©Martyn Phillis greater mouse-eared bat