26 THE BIRDS OF THE BRITISH ISLES. 



ranges over northern and central Europe, but is rare in the 

 south ; throughout its range, including Britain, it is partially 

 migratory. Regular migration is complicated by irregular 

 movements in summer and winter ; large numbers of immi- 

 grants reach our eastern shores in autumn and return in spring, 

 and emigration is noticeable in the south-east in autumn and 

 a more marked immigration reaches our southern shores in 

 spring. These southern movements are supposed to be those 

 of British-bred birds, but some immigrants from northern 

 Europe may be birds of passage. Thus the Rook is at once 

 a resident, a winter visitor, a summer visitor and possibly 

 a bird of passage. In Ireland the movements are further 

 complicated by short, irregular migrations across the Irish 

 Sea, and by occasional abnormal westward flights that have 

 sometimes ended in disaster in the Atlantic. Exhausted birds 

 arriving on the west coast of Ireland and the Hebrides were 

 supposed to be survivors from these misguided attempts to 

 extend the range, but it is as likely that they were south- 

 bound autumnal emigrants that had miscalculated the wind 

 direction and weather conditions. 



The feather-denuded rough skin round the base of the bill 

 of the adult Rook, the slender and less curved beak, blue sheen 

 and voice are characters which distinguish it from the Carrion, 

 but in the young bird, until a year old, the nostrils are clothed 

 with bristles and the chin feathered. At all ages, however, the 

 feathers of the flanks hang loosely, giving the bird a more 

 ragged, skirted appearance round the thighs than the Crow. 



The Rook is a sociable bird, amiably consorting with the 

 Jackdaw, which joins it in the fields and the winter roosts and 

 occasionally at the rookery. In the fields the Rook follows the 

 plough, walking erect, with sedate, slightly rolling gait, and 

 with occasional short flights to the heels of the ploughman. 

 The morning and evening flights, from and to the rookery or 

 roost, are familiar to all ; with steady, regular wing-beats and 



