 The corn crake is solitary on the wintering grounds , where each bird occupies 4 @.@ 2 – 4 @.@ 9 ha ( 10 – 12 acres ) at one time , although the total area used may be double that , since an individual may move locally due to flooding , plant growth , or grass cutting . Flocks of up to 40 birds may form on migration , sometimes associating with common <unk> . Migration takes place at night , and flocks resting during the day may aggregate to hundreds of birds at favoured sites . The ability to migrate is innate , not learned from adults . Chicks raised from birds kept in captivity for ten generations were able to migrate to Africa and return with similar success to wild @-@ bred young . 
