218 Among the Birds in Northern Shires. 



time, a rare straggler of some non-indigenous British 

 species appears, and the light-keepers have repeatedly 

 assured us that at intervals the sea around them 

 during winter often swarms with Ducks and other 

 northern birds. It is, however, in spring and sum- 

 mer that the islands become crowded with their 

 normal inhabitants Gulls, Terns, Eider Ducks, 

 Cormorants, Ringed Plovers, Oyster-catchers, Guille- 

 mots, and Puffins assembled there for the express 

 purpose of rearing their young. One of the most 

 characteristic birds of the islands is the Lesser 

 Black-backed Gull in fact the entire group may be 

 regarded as one vast colony of this species, and 

 perhaps the most densely populated one throughout 

 the length and breadth of the British archipelago. 

 These birds return to the islands coming from 

 the south from many parts of the German Ocean 

 and the English Channel early in spring, but the 

 exact date varies a good deal in different years. In 

 some seasons they return en masse as early as from 

 the middle to the end of March; in other seasons 

 not before the middle of April. A month later they 

 are engaged in nesting duties. The date of breeding, 

 however, varies little, and the eggs are invariably 

 laid during May and June. On approaching some 

 of the islands, the first impression is that this Gull 

 monopolizes the whole of the ground, as it occurs 

 in such vast abundance. The air seems full of them, 



