How the UK's rarest bat species are staging a comeback

Times

25-07-2025

In a dark network of tunnels in West Sussex you'll find a pair of greater mouse-eared bats. By all rights, these large bats shouldn't be there.
One of 18 bat species found in the UK, the greater mouse-eared was thought to have been pushed to extinction in Britain during the 1980s.
However, one male was found in the disused railway tunnels in 2002, leading him to be called the UK's loneliest bat. Assuming he was still alive — they can live for 35 years — he became a bit less lonely when a second was spotted and the known population doubled.
In January it became practically a party, when conservationists were delighted to find a third at an undisclosed location in Sussex. Even better, it was an adult breeding female. In ecologists' parlance, the foothold is still so fragile that the greater mouse-eared is considered a 'vagrant' rather than a 'resident' British species.
However, Daniel Whitby, a bat conservationist, said the third offered huge hope. 'It does indicate some tiny residual population that could have clung on, just a few individuals, and there could be something here,' he said.
The greater mouse-eared is one of several bats showing potential to become that most critically endangered of species: a conservation good news story.
Not all of the 18 bat species are monitored well enough to tell how they are doing. But for those that are, the populations of five have increased since 1999, and six remained stable.
Just last week there was welcome news for the second-rarest species, the grey long-eared bat. Down to about a thousand individuals nationally, the droppings of one was found in Kent, the first evidence of the species in the county for four decades.
However, the bat may simply have been a migrant that strayed over from Sussex, which Whitby said would not be surprising given the males of the species are known to wander far. 'What would be really interesting, a real success story, is if it's a breeding colony [in Kent],' he said.
The health of the grey long-eared is far from a tale of unalloyed happiness. In recent years the only known breeding colony in Sussex, in the Petworth area, was destroyed by builders. 'The [Sussex] population, if anything, has probably gone down,' Whitby said.
Some rare species have benefited from a helping hand. The greater horseshoe, which is about the size of a small pear and whose numbers crashed 90 per cent in the last 100 years, declined largely owing to timber insecticide treatments wiping out its food. However, there are about 13,000 today, up from a low of roughly 4,000 in the 1980s.
Their stronghold is southwest England and south Wales but, aided by projects such as Vincent Wildlife Trust's Horseshoes Heading East, their numbers are growing further east too.
Though there have always been some in Sussex, in the past 14 years Whitby and other experts including Scotty Dodd discovered several roosts in the county. In some cases they installed heaters, or incubators, to increase the chances of healthy pups being born. Strict planning laws, habitat protection, bat-friendly modifications to buildings and a reduction in the use of toxic chemicals are aiding bats too.
Ryan Greaves runs bat safaris at the Knepp estate in West Sussex, where rewilding efforts have increased the number of species from five to 13, including rare Bechstein's bat and barbastelles. He was part of a project with the Sussex Bat Group that bought up a building home to greater horseshoes in the village of Lodsworth, to save it from being sold off for development or knocked down.
Volunteers at Vincent Wildlife Trust making roosting boxes and pots to go inside
DANIEL HARGREAVES
DANIEL HARGREAVES
• Why the Knepp rewilding project is truly magical
Bats are harder to detect, monitor and count than birds, but technology is helping. Whitby used ultrasonic lures to call Bechstein's bats for the first national survey of the species two decades ago, discovering seven colonies in one summer. A citizen science project in Chichester used detectors in people's gardens to detect the ultrasonic chattering of rare bat visitors.
The nascent recoveries of some bat species are still tentative: 4 of 11 native British mammals at the most imminent risk of extinction are bats. And a bat renaissance is far from a foregone conclusion, with ministers accused of being 'nasty' to them with Labour's planning reforms and rhetoric about HS2's £100 million 'bat tunnel '. But there is hope that our bats may be a little less lonely in the future.