286 BRITISH SEA BIRDS. 



of certain Arctic-nesting species, frequenting the 

 British coasts throughout that season. The 

 presence in our area of these northern birds 

 during summer, has not unnaturally led to the 

 supposition that they actually breed there. In 

 autumn the order of migration is, to some extent, 

 reversed. At that season a few old birds of either 

 sex are the first to arrive, sometimes preceding, and 

 always invariably accompanying, the flights of 

 young birds, which are then moving south. Many 

 of these young birds start off from their birth-place 

 almost as soon as their wings are strong enough to 

 bear them, and individuals of certain Arctic species 

 have been met with on our coasts with particles of 

 the down of their nestling plumage still adhering to 

 their feathers. The adult males come south next ; 

 the females following ; and last of all come the 

 cripples and the weakly the individuals that have 

 been retarded in their flight by accidents of various 

 kinds, such as the loss of wing feathers, by deformi- 

 ties, or by disease. The observer on the coast will 

 also remark considerable diversity in the social or 

 gregarious tendencies of these migrants. Some 

 migrate gregariously in numbers that are as un- 

 countable as the pebbles on the shore ; others 

 journey in family parties, in small flocks, or even 

 singly. The migration of each species is usually 

 first remarked by the appearance of an odd bird 

 or two ; then the numbers increase, perhaps with 

 two or more great rushes when the flight of that 



