A “callow” is a very special habitat. Callows are seasonally flooded grassland ecosystem found on low-lying river floodplains. The IWT own a callow reserve on Bullock Island. An island located within the Shannon Callows and inundated by the great river each year. Due to this seasonal flooding the callows have never been under intensive agriculture. It is for this reason that the callows were one of the last refuges of the corncrake, an endangered native species of bird that has suffered greatly from the modernisation of agriculture.
In winter this reserve is under the river Shannon and in summer the island is one great swaying sea of hay.