Some of Ireland's scarcest and most vulnerable species, such as barn owls, choughs and lesser horseshoe bats, are being made homeless by the restoration of ruins and archaeological sites.
Mr Gordon d'Arcy, an environmental scientist in Co Galway, told the first annual conference of the Institute of Archaeologists of Ireland in Mullingar that some of these sites could be "veritable wildlife storehouses, supporting rich flora and fauna, inside and out".
In his address to the newly formed institute, he said this was usually ignored, or at best given cursory consideration, in projects to restore buildings ranging from early churches to medieval tower houses and larger ecclesiastical sites and ruined demesnes.
Mr d'Arcy instanced one medieval tower house, Gleninagh in Co Clare, which until recently held the only pair of breeding choughs in the Burren.
"Recent reopening to the public has probably resulted in their disappearance," he said.
A wealth of flora and fauna had also been discovered at Caherillan, a ruined 15th-century tower house, near Kinvara, Co Galway, including hibernating insects such as tortoiseshell butterflies, herald moths and wild bees, as well as long-eared bats.
"The abundance of twigs and straw pointed to the ruin being used in the spring and summer as a nest site for starlings, jackdaws and sparrows," he said. "A raven's nest, obviously awaiting refurbishment, occupied a window ledge in an upper storey."
Souterrains could also be important hibernating places for bats and other mammal species while fulachta fiadh (prehistoric cooking sites) could be used as marking spots for otters because they were often located adjacent to natural springs.
Calling for policy on archaeological restoration to be reconsidered, Mr d'Arcy said a case could be made for leaving part of a structure such as a ruined tower house completely untouched by restoration "for the sake of its wildlife incumbents".
Ms Daire O'Rourke, an archaeologist with the National Roads Authority, told the conference that its policy was to avoid archaeological sites. Where this was not possible, a full archaeological mitigation strategy was carried out on a route-by-route basis.
Indirectly, the current national road-building programme had led to the largest scale of archaeological investigation ever undertaken in Ireland by a single developer, and this would add greatly to understanding the country's cultural heritage.
A Galway archaeologist, Mr Michael Gibbons, gave the conference an account of his investigations of the "astonishing array" of archaeological material beneath the sea between Connemara and the Aran Islands.
"It varies from an early intertidal coaxial field system at Tra Mhór, on Inis Mór, to a host of sub-sea holy wells, tidal mills and a rich assortment of wrecks, including a number from the 1588 Spanish Armada and a possible Viking raiding base," he said.
