ON, BIRD MIGRATION. 299 



Some Rooks leave the south-east shores of England in the autumn, 

 and thougli such emigrations, or passages, are somewhat scantily re- 

 corded, yet the corresponding return migrations in the spring are 

 regularly chronicled. A similar spring immigration is also observed 

 on the south-east coast of Ireland. The above-mentioned movements 

 constitute the regular migrations of the Rook as observed in Great 

 Britain and Ireland. 



In addition, some irregular migrations and interraigrations come under 

 notice, for the bird is much given to wandering, especially after the close 

 of the breeding season and during the summer, when flocks consisting 

 of old and young visit the vicinity of the coast and some of the neighbouring 

 islands ; food of a particular nature being, presumably, the main incentive 

 for these roving movements. 



In Ireland, with the exception of the spring immigration already 

 mentioned, the movements, both local and intermigratory, are to be I'e- 

 garded as being only of a partial or irregular nature. 



In severe winters Rooks, in small numbers, have been recorded as 

 seeking certain of the Outer Hebrides in search of more genial quarters 

 than those afibrded by the mainland. To others of these islands it is a 

 regular winter visitor. 



Apparently erratic movements out into the Atlantic have been known 

 to take place in the autumn. 



Although one of our most familiar birds — a species known to all ob- 

 servers — yet there is a lack of information regarding the movements of 

 the Rook that is not a little surprising : further and striking proof of the 

 great difliculties which enshroud the whole subject of bird migration. 



Autumn Immigration from Central Europe. — This is by far the most 

 important of the autumn migrations of the Rook witnessed on our shores, 

 for it is from Central Europe that we receive the great majority of the 

 birds which winter in Britain. 



The immigrants arrive on the south-east coast of England, from the 

 Humber to the coast of Kent, at dates ranging from the latter half of 

 September to mid-November,' the greatest numbers appearing during late 

 October, when these movements are often in progress for several succes- 

 sive days, during which vast numbers pour in upoia our shores.^ 



The direction of the flight varies, being usually from direct east to 

 west at or about the mouth of the Thames (and sometimes on the coasts 

 of Norfolk and Kent) to north-west and north-north-west on the coast of 

 SuflFolk and northwards. Occasionally numbers are observed ofi" the 

 mouth of the Thames and east coast of Kent moving north-west across 

 the Straits of Dover, as if coming from the north-east coast of France. 

 On reaching our shores the immigrants proceed inland in search of winter 

 quarters. 



The movements are only observed during the daytime, usually between 

 9 A.M. and 4 p.m. ; and the birds pass the lightships in straggling flocks, or 

 sometimes in small parties (even of two or three individuals), and frequently 

 immense numbers pass in a single day. 



The most frequent companion of the Rook on these occasions is the 

 Daw, though always in smaller (usually much smaller) numbers than its 

 the other species also migrating in company, or at the same 



' The first recorded appearance is September 16 in 1880. 

 - In October 1884 the migrations covered twenty-two days. 



