296 THE NESTS AND EGGS OF BRITISH BIRDS. 



there in little precipices to the sea. It is probable that 

 this species pairs for life. The Common Gull is gregarious 

 during the breeding season, but the colonies vary con- 

 siderably in size, and many pairs are scattered about 

 in some localities where the bird is not common, or suit- 

 able sites are scarce. Late in April the birds congregate 

 at their breeding-stations, and nest-building soon after 

 commences. The nests are placed in various situations. 

 Some are made amongst crevices of the rocks, others 

 amongst grass and heather ; some in hollows in the bare 

 turf, others on ledges of cliffs. In Norway this Gull has 

 been known to lay in the deserted nest of a Hooded 

 Crow in a pine tree. The nest is made of heather 

 branches, turf, dry grass, or sea-weed and stalks of 

 marine plants, and lined with grass, in some cases almost 

 green : occasionally the nest is little more than a mere 

 hollow. When disturbed at their breeding-place the 

 birds become very clamorous, and fly to and fro in alarm. 



RANGE OF EGG COLOURATION AND MEASUREMENT : 

 The eggs of the Common Gull are usually three in 

 number, but sometimes four. They vary in ground 

 colour from olive-brown to buffish-brown, spotted and 

 often streaked with dark brown, and with underlying 

 markings of brownish-gray. As usual, most of the 

 markings (from the size of buckshot downwards) are on 

 the larger end of the egg, where they sometimes form an 

 irregular zone, but some varieties are more evenly spotted 

 over the entire surface. Average measurement, 2*25 

 inches in length, by r6 inch in breadth. Incubation, 

 performed by both sexes, lasts about a month. 



DIAGNOSTIC CHARACTERS: The size and style of 

 colouration (small spots rather than blotches) make the 

 e gg s f this Gull very distinct, and prevent their con- 

 fusion with those of allied species breeding in our 

 islands. 



