It is thought that most of central and western Europe used to be inhabited by the corncrake.
History of decline - why is the corncrake endangered
Availability of increasing areas of cultivated land caused an extension of range in northern Europe and western Siberia in the past.
The species started declining in western Europe in the mid 19th century coinciding with the start of the mechanisation of the agricultural systems and earlier cutting of the hay harvest. Since the 1950s the rate of decline accelerated, coinciding with a period when majority of hay fields were changed to silage production, which allowed even earlier cutting dates, and often production of two crops from a field.
This was first noticeable in Britain, Ireland, Fennoscandia and west-central Europe, and since 1970 the decline spread through most of the European range of the species, including some of its east European strongholds. During 1970-1990 all countries except Sweden and Finland recorded declines in excess of 20 per cent (in ten countries more than 50 per cent).
In Britain the decline started in south-east England in the mid-19th century and gradually spread north and west. By the late 1930s corncrakes were absent from much of England and southern Wales, and large parts of Scotland. Only in the northern and western islands were they still abundant. In Ireland the decline started later and spread more slowly, though more recent decline since 1988 has been dramatic.
The declines throughout the corncrakes range were closely linked to periods of change in the farming systems: from the mechanised cutting and earlier cutting dates to the change from hay to silage with its associated even earlier cutting dates, and often production of two crops from a field. In many areas cutting is now so early that suitable nesting habitat no longer exists in the breeding season. Major investment in drainage schemes in the 1980s allowed silage production to spread to many poorly drained areas in Scotland and Ireland, which until then had remained untouched.
The speed at which agricultural changes can affect the corncrake is illustrated by the 80 per cent decline in numbers in Northern Ireland in three years (1988-1991), which coincided with earlier cutting dates as farmers were encouraged to produce silage instead of hay and increased sheep stocking which resulted in further loss of hay meadows.
In Britain and Ireland there have been unprecedented declines in numbers throughout the range of the species, accompanied with 76 per cent contraction in range since 1970. By the 1990s the annual decline was so great that, had it continued, the species would have gone extinct in the British Isles within 10-20 years. As a result of conservation measures in the core areas, the decline was finally halted with the lowest point in Britain in 1993 with 480 calling males, and in Republic of Ireland in 1994 with 129 calling males. Since then the numbers have slowly increased.
In Northern Ireland corncrakes were still widespread at the time of the 1968-71 Atlas, but by mid-1980s their range had contracted to the western counties, particularly Co. Fermanagh. During the 1994 breeding season no corncrakes were recorded, and only a few birds have been found since.