The corncrake is one of Britain's most endangered birds — a secretive, ground-nesting migratory species whose distinctive rasping "crex crex" call was once a common summer sound across British meadows. Today, the UK breeding population is restricted almost entirely to the Western Isles of Scotland and a few other island sites, with a total population of around 800–1,200 calling males. Once numbering in the tens of thousands across mainland Britain, the corncrake's decline was driven almost entirely by agricultural mechanisation and the shift from late-summer hay to early silage cutting.
The primary cause of corncrake decline is mechanised grass cutting for silage and hay. Modern mowing machines cut earlier and faster than traditional methods, trapping and killing nesting adults, chicks, and eggs. The shift from July/August hay cutting to May/June silage cutting means fields are cut during the birds' most vulnerable breeding period.
Corncrakes require tall, dense vegetation for cover throughout the season. Intensification has reduced iris beds, nettle patches, and rank meadow grasses that provide essential refuge habitat.
Corncrake management agreements through Rural Stewardship Scheme (Scotland) and equivalent schemes compensate farmers for delayed cutting and habitat management. These payments have been critical to maintaining the remaining UK population.
UK conservation efforts have stabilised the Scottish island populations and even produced modest recovery. Reintroduction attempts in England and Ireland continue. The species remains acutely vulnerable to any reduction in management support.