Skittering and drumming noises above the ceiling of my workroom a few weeks ago suggested a bat might be stretching its wings for spring. The silence since then suggests it has moved somewhere cooler - I hope not too far. Just one tiny pipistrelle can eat 3,500 insects in a night and there are whole clouds of midges in the garden I would gladly see reduced.
Our larger bats eat a lot of less obvious things. The yellow dung fly of cow pats, Scatophaga stercoraria, are consumed by the million over cattle pastures just after sundown - a notably Irish phenomenon. For Leisler's bat, our biggest and fastest species, this one fly is actually the most important prey.
Centipedes, would you believe, are eaten by Natterer's bat and the brown long-eared bat, both of which go in for "gleaning" insects - snatching moths, earwigs, beetles and spiders from the leaves of trees and shrubs, and even from the ground.
Bat study now involves a lot of high-tech work: tracking them as they forage by radio telemetry and identifying them by bat detectors tuned to the different frequencies of the "feeding buzz" or echolocation call. But the best way to know what different bats are eating is still to take a microscope to their droppings.
These can be very numerous; just the thought of them piling up is enough to worry some householders, unappreciative of free insulation. They should consider St Patrick's Church at Slane, Co. Meath, where pipistrelle droppings in the attic over the nave are about 60cm thick - but the bats have been roosting there since 1712.
This emerged in a survey last year of bat roosts in Church of Ireland churches in the eastern counties, funded by the Heritage Council. These old buildings are important roosts for bats, especially the kind that need large, open attics to hang in. One surprise was to find long-eared bats still roosting in summer in the C of I church at Castleknock in the dense Dublin suburbs - and foraging, probably, in the new woodland along the nearby M50 motorway.
The links between safe roosts and good foraging grounds, especially for Ireland's more important species, will be one theme of the second Irish Bat Conference, to be held at Ballyvaughan in the Burren on June 4th-6th. Work on bat behaviour and conservation has become one of the liveliest branches of Irish mammal research, and Co. Clare, with its limestone caves, old buildings and wooded valleys, is the logical place to meet.
Its big treasure is the lesser horseshoe bat, here at the most northerly point of its range. It is already rare in much of Europe, reduced by disturbance, loss of habitat and toxic treatment of roof timbers. In Ireland, too, the traditional bat of the big house attic is under threat, as old slated buildings fall to ruin or are renovated. Since the last count a decade ago, the 12,000 horseshoes have lost many important summer roosts, and have been forced out to doss in empty cottages and sheds.
This is why the Heritage Council stepped in to buy an old building at Dromore, disused for 20 years but about to be put on the market. It has what is probably the largest maternity roost of lesser horseshoe bats in Europe (428 animals, at one count last August). Now the building will be restored and used for teaching about the bats "upstairs".
They have been followed as they head out at dusk to forage in nearby Dromore Wood, already a nature reserve. They take a linear route, flying along hedgerows and stone walls, rather than crossing the open fields to the wood. So these "bat-line" features will also need protection in a Special Area of Conservation. Meanwhile, the lesser horseshoes of Dromore and other sites in Clare, both in summer roosts and winter hibernation hideaways underground, are monitored by Duchas's local conservation ranger.
The Dromore project complements the conservation work for Ireland's lesser horseshoes funded since 1991 by the Vincent Wildlife Trust, a UK mammal charity. It has bought or leased old buildings that were falling apart around the bats and rebuilt or repaired them to make them secure. And it has helped Duchas to conserve a large nursery colony of Leisler's bats in the roof of an occupied house in the north-west - this by building an insulated roof-space within a roof-space, so that the family downstairs are no longer bothered by their lodgers.
Ireland has probably the best population of Leisler's bats in Europe, but the latest project of the Vincent Wildlife Trust hopes to find one of Europe's rarest species, the barbastelle, a bat with black fur, a pug nose and big ears. In 1997, two Scandinavian experts on bat echolocation came to Ireland to make recordings of Leisler's bats, and picked up what they believe were the calls of the barbastelle, hitherto unknown in Ireland.
The species uses tree holes to roost in, so the trust has set up 162 bat boxes in three Irish woodlands, to be checked once a month from spring to autumn. Whether or not the barbastelle is found, the boxes could tell more about the use of woodland by the less recorded species, such as the whiskered and Natterer's bat.
Barbastella barbastellus would, in fact, be the ninth Irish species, after years in which we thought the island had only seven. One of the speakers at the Ballyvaughan conference, Jon Russ from Queen's University, is the man who discovered the eighth, Nathusius's pipistrelle, in 1997. Indeed, there were about 150 of the bats in a mid-19th-century stable block in a park on the outskirts of Antrim town. This is the most westerly maternity colony yet known and raises big questions on the spread of a normally strongly migrant species.
I have saved up the names of the other researchers deliberately to make a point. The traditionally bad public image of the bat, which can make problems for conservation, has much to do with the irrational fears and squeamishness of many women. Yet women now lead the field in Irish bat research.
Caroline Shiel has been working on diet and foraging behaviour, using radio telemetry; Niamh Roche climbed high, shaky ladders to wriggle into church attics; Rebecca Cogan has been following the bats from Dromore; Congella McGuire is the Burren conservation ranger who monitors the lesser horseshoes and soothes people worried about bats in their roofs; Kate McAney is the conservation fieldworker for the Vincent Wildlife Trust. There are another eight women among the speakers at the Ballyvaughan conference.
For details, contact Kate McAney at Donaghpatrick, Headford, Co. Galway (09335304; email:
