The corncrake, a bird once common in lowland Britain but whose harsh nocturnal call is now mainly confined to the Scottish Isles, is yielding secrets of its habitat requirements which may enable scientists to devise a strategy to preserve it in its final strongholds.
A team from the Royal Society for the Protection of Birds working in South Uist in the Outer Hebrides has found that the corncrake has a clear preference for a cultivated habitat of hayfields, rather than the dry and improved sheep-gazed turf machair, or wetter peaty soils.
Radio transmitters were fitted to 12 male corncrakes last summer to pinpoint the movements of the elusive Crex crex, whose position is often betrayed only by its insistent night call.
The research has confirmed a long-held suspicion among scientists that the crakes move out of their calling points in iris beds and travel up to half a kilometre a day to feed, passing through the calling areas of several neighbouring birds, before returning to their habitual night habitat.
The home range of about 40 hectares a bird is considerably larger than the area a crake was thought to require. The birds were found to use drainage ditches, which conservationists previously thought ecologically retrograde, as a means of walking undetected around the fields.
The corncrake's decline was first noted in the 19th century in the hay meadows of south-east England and is believed to have been hastened by mechanization of harvesting.
The hand scything still practised in parts of Scotland allows the farmer to spare nests. The most recent study in 1983 recorded only about 700 calling birds in Britain, almost all of them in north-west Scotland, with about a third in the Western Isles.
The three-year study, part funded by the Nature Conservancy Council, is designed to show whether EEC agricultural regimes are detrimental to the bird.
The RSPB team has returned to South Uist for a second summer to radio-tag females, to learn more about nesting habits and where they lead their young. The team wants to find causes for the bird's low breeding productivity: only four or five young usually survive past the nest from clutches of 11 or 12 eggs.
By the end of next year, the RSPB hopes to complete a corncake conservation strategy that would be applicable throughout Europe.
"We hope to suggest ways to enable farmers to continue their activities so that they benefit the corncake and make a living," Mr Tim Stowe, project leader, said. "We must maintain at least the existing traditional cropping system or lose the corncake."
