GEE AT BLACK-BACKED GULL 437 



stems, and seaweeds. The eggs, two sometimes three in 

 number, are yellowish-brown or stone-colour, heavily 

 blotched with umber and greyish-brown. 



Incubation begins in May. 



Around the sea-board of Northern Britain, including 

 the large Island-Groups, the bird is fairly abundant in the 

 nesting-season. Colonies of over twenty pairs breed in tbe 

 Outer Hebrides. 



Likewise, round the greater part of the Irish coast it 

 may be found breeding, except, perhaps, in the north-east. 

 In the west it is more numerous than the Lesser Black- 

 backed Gull. 



Along the English coast its breeding-haunts are much 

 more restricted, the south and west sides, including Wales, 

 harbouring only limited numbers. 



Geographical distribution. Abroad, this species is 

 widely distributed over Northern and Temperate Europe, 

 Greenland, and the North-eastern section of Canada. On 

 migration, in autumn and winter, it occurs as far south as 

 the shores of the Mediterranean and the Canary Islands on 

 the North African coast. Westward, along the American 

 sea-board, it reaches lat. 30 N. 



DESCRIPTIVE CHARACTERS. 



PLUMAGE. Adult male nuptial. 1 Head, neck, breast, 

 abdomen, and tail, white ; back and wings, slaty-black ; 

 all the primaries, broadly tipped with white ; outer 

 primaries, chiefly blackish, except the tips ; outer webs of 

 other primaries chiefly blackish, inner webs, greyish ; 

 secondaries and scapulars, also tipped with white forming 

 an alar bar. 



Adult female nuptial. Similar to the male plumage. 



Adult winter, male and female. Differs from the nup- 

 tial plumage in that the head and neck are streaked with 

 greyish -brown. 



Immature, male and female. Dappled with greyish- 

 brown like the immature Herring-Gull, but the markings 

 are paler and more defined. Seasonal plumage-changes. 



1 1 have seen this bird retain its nuptial plumage throughout the winter 

 in a state of captivity. 



