But in parts of the Western Isles, in particular on the islands of Coll, Barra, Islay, Lewis and on the Uists, corncrake numbers are rising sharply. This year Tiree, west of Mull, recorded the largest population - 121 calling males and about 120 females, up from a total of 200 birds last year.
The corncrake's recovery is the result of a new land management programme established by the Royal Society for the Protection of Birds, Scottish Natural Heritage and the Scottish Crofters' Union. Under the scheme, smallholders are paid up to pounds 50 a hectare to delay harvesting hay meadows - the bird's main nesting ground - until 1 August. Additional payments are made to farmers who adopt 'friendly mowing techniques' - cutting from the centre of the field outwards, rather than from the periphery inwards.
Late harvesting, RSPB officials say, allows corncrake chicks time to fledge before the tractors move in, while 'inside-out' mowing ensures that the birds can move out of the path of the harvesting machines.
Miss Evans, an RSPB officer who monitors the corncrake initiative on Tiree, explained: 'Corncrakes depend on hay meadows for nesting sites and food. In recent years farmers have begun to harvest hay fields earlier than ever before, destroying nests and killing chicks.
'But here in the Hebrides, farming techniques mean that many of the young have left their nests by the time the harvesters arrive, and those that remain find it easier to avoid being cut to pieces by the mowers.'
More than half of the island's 80 crofters have joined the conservation scheme, many using the payments to meet the cost of baling their silage.
Iain Mackinnon, who has worked his croft at Ruaig for more than 50 years and will receive more than pounds 300 through the scheme this year, said: 'Sometimes now the males' calling is so loud it keeps you awake. It's good to see them returning.'