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Corncrake Trends

Corncrakes were once common in Ireland. Conservative estimates put the population at the turn of the century in the tens of thousands. By the late 1960s, the population had declined to about 4,000 singing males. An All-Ireland census carried out in 1988 found that the population had dropped to just over 900 singing males, and when this census was repeated in 1993, only 174 singing males were recorded - a decline of over 80% in just five years. This survey also found that Corncrakes were now restricted to three core areas in Ireland - the Shannon Callows, North Donegal and Co Mayo (the Moy Valley and the Mullet). By 1994 numbers had fallen further, to 129. Click on the graphs opposite to view the population changes in the core areas and throughout Ireland.

 
Recorded declines in Corncrakes corresponded to the replacement of traditional farming systems by modern agricultural methods. Increasingly sophisticated machinery meant that grass could be cut earlier in the year and the harvest was completed quicker than before. Farmers also began to take several crops of grass per year. Earlier mowing dates prevented Corncrakes (and some other ground-nesting birds) from successfully rearing young in the meadows. Research has shown that, in order to maintain stable population levels, Corncrakes need to hatch two broods of chicks per year. As the peak hatching date for the second brood is in late July, Corncrakes will decline rapidly in areas where most of the mowing takes place before early August.

In the latter part of the last century, an increase in livestock, particularly sheep, in some areas led to a reduction in the area of tall vegetation available for Corncrakes, especially when they arrived in spring and this contributed to declines. The method of mowing used is also important in Corncrake survival. Young chicks are particularly reluctant to cross open ground, and may become trapped in an island of remaining grass at the centre of the field if mowing proceeds from the outside of the field inwards.

 
As a result of conservation measures, however, numbers rose for the first time in 1995. The All-Ireland census, which is carried out on a five-yearly basis, took place again in 1998. The results of this showed the overall number in the core areas to be 149-153 singing males, with only two of these males recorded outside the core areas. Numbers in 1999 and 2000 showed some stability with around 150 singing males recorded. Despite the declines observed on the Shannon callows over recent years, increases recorded in Donegal and West Connacht have left the overall population at 150 calling males in the three core areas in 2007.

For a summary of corncrake fieldwork in Ireland in the last two years, click on the links below.

Summary Report, 2007

Summary Report, 2008



 

 

 

 

Corncrake population change in core areas 1990-2007 (click to enlarge)

Corncrake population decline across Ireland, 1976-2008 (click to enlarge)

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