Another Life: Out to bat for the lesser horseshoe

Some old mineshafts in the west feel much more like caves: they are adits driven into rocky hillsides in the hope of striking silver or lead. One I remember had been the unsuccessful venture of a Connemara landlord in the 19th century. Clambering through a hill stream at the entrance, and penetrating just enough into the dark, I was shown today’s ecological treasure: a roost of lesser horseshoe bats.

The "horseshoe" surrounds their noses, fleshy, circular discs of tissue that help mark out Rhinolophus hipposideros from all the other bats in Ireland. These bats are also unusual in hanging freely, upside down, when at rest, rather than tucking themselves into crevices as the common pipistrelles do. Those in the mine looked like some strange fruit, wrapped around in dark silk – "plum-sized", as Dr Kate McAney puts it.

No one in Ireland knows more about them than she does. She began studying them in Co Clare in the 1980s out of NUI Galway, and then in working full-time for the UK's Vincent Wildlife Trust. This remarkable exercise in philanthropy was founded by 78-year-old Vincent Weir, younger son of a baron in a UK shipping family. His passion for conservation gave the Republic its first nationwide survey of otters, in the late 1970s, and since 1991, under McAney's leadership, a growing protection for the island's smallest but most notable bat.

Both greater and lesser horseshoe bats are in serious decline across Europe, but R hipposideros has found continuing refuge in Ireland's western counties – about 12,500 of them at current estimate. Checking out where more than 8,000 of them live has been an immense task, spread over a decade of winter and summer surveys. It is described now in The Lesser Horseshoe Bat in Ireland, a special supplement to the Irish Naturalists' Journal, produced by a five- strong team with McAney as editor.

Bat of the aristocracy
There was a time when this little mammal was labelled "the bat of the aristocracy", given its frequent choice of roosting in the attics, outbuildings and ice houses of Ireland's mansions. Today, however, through dereliction, demolition or renovation, most of the roosts have been forced downmarket, as it were, into the open windows of old, unoccupied stone cottages and cowsheds with slate or even rusting tin roofs. And although the Vincent Wildlife Trust has bought or leased seven buildings serving summer maternity roosts – all but one in Co Kerry – the new report shows how close the Tiger years came to making further inroads on the animals' last surviving summer refuges. This seems to have made the bat scarcer in several sought-after areas of the west.

The trust’s 10 years of surveys, helped by the existing knowledge and manpower of the National Parks and Wildlife Service, involved searching 3,442 structures. Getting permission from the owners involved, as the team says, “occasional encounters with an aggressive animal, not always of the canine variety”.

Knocking at the door could often lead to a welcoming cup of tea, but “some of the people encountered were suspicious of anyone undertaking wildlife survey work and were resentful of European environmental legislation. Several expressed concern that the discovery of bats on their property would prevent future development . . . Some landowners clearly stated that they would only undertake conservation measures if there was a financial incentive, while some admitted previously destroying bat colonies in their properties.” All this will have a familiar ring to Ireland’s field ecologists and wildlife wardens.

Hazards
The actual surveying had its own hazards, especially underground, in winter and using ladders and ropes. Each team included an experienced caver, and one newly surveyed cave in Kerry was found to hold 90 hibernating bats. But outside of cave areas such as Co Clare, where about 750 bats use three caves west of Ennis, most of the wintering horseshoes have adapted to man-made structures such as big-house cellars and ice houses, tombs and souterrains.

Even with an end to the runaway construction of the Tiger years, the future of the horseshoes’ summer roosting and maternity quarters is increasingly insecure, as uninhabited stone houses and barns are allowed to rot to the gables, are demolished or are sold on for renovation, perhaps without mention of any inconvenient bats.

The team wants the last to be illegal. But it does also suggest that past measures, imposed to secure the future of roosts, have sometimes been “excessive” and “exorbitant in design and technology”, not always helpful to the bats, and even driving some developers to prefer paying penitential fines, instead. The measures, it says, should be “adequate to the needs of the species”.

Things were so much simpler, McAney may reflect, when she could protect an ice-house roost by installing the right kind of grille.

The Lesser Horseshoe Bat in Ireland is €12 (or £10) from irishnaturalistsjournal.org