In the Shannon Callows the population appeared to be more or less stable until severe summer flooding in 2002 disrupted breeding. Only 20 singing male Corncrakes were recorded that year, a decline of 63% from the previous year. Following intensive conservation efforts and the operation of emergency grant schemes to protect this fragile population, small increases were recorded over the following few years with 23 males counted during the 2005 census. However, a further blow was delivered to the conservation efforts with another summer flood on the Shannon Callows in 2006, and an extremely wet summer in 2007. As a result, the already vulnerable population fell to an all time low of just 17 calling males in 2006. This worrying decline continued with only nine calling males being confirmed in 2007, and just four in 2008.
Since 2002 numbers have risen dramatically in Donegal with steady growth in West Connacht. The overall effect of the decline in Shannon Callows and growth in Donegal and West Connacht has lead to a national breeding population which have neither risen nor fallen, but remained at a steady level. This demonstrates that the conservation programme is having a positive affect and is curtailing the severe declines.
Corncrakes have declined throughout Western Europe, but in areas where conservation projects have been initiated this decline has been slowed and, in a few cases, reversed (e.g. in Scotland there have been significant increases in recent years with the numbers increasing from 463 in 1994 to over 1,000 in recent years). In Eastern Europe and Russia there are still large numbers of Corncrakes. However, populations in these areas are also threatened, as political changes may lead to rapid intensification in agriculture.