298 THE NESTS AND EGGS OE BRITISH BIRDS. 



are made on ground studded with low bushes and trees, 

 or are completely surrounded by woods and plantations. 

 This Gull is very gregarious during the breeding season, 

 some of its colonies consisting of many thousands of 

 pairs; everywhere the same social instinct is manifest, 

 even though the assemblage numbers but a few indi- 

 viduals. In March the Gulls begin to congregate at the 

 old colonies, so that we may infer they pair for life, 

 many of these breeding-stations having been in use for 

 time immemorial. A month later the nests are being 

 made or repaired. These are built in the majority of 

 instances on the ground, but odd pairs have been known 

 to make them in trees, or even on boat-houses. The nests 

 are placed in tufts of rushes, in hassocks of coarse grass, 

 amongst reeds in shallow water, on heaps of dead, broken 

 vegetation, or even on the flat ground, either covered with 

 spongy moss or bare of all vegetation whatever. In 

 many cases the nest is little more than a hollow in the 

 ground or tuft, sometimes roughly lined with a little dry 

 grass ; in others it is better made, banked high above the 

 surrounding marsh or shallow water, and made of reeds, 

 rushes, flags, and coarse grass. As incubation advances, 

 many of the nests made in the shallows are increased in 

 bulk, so that the newly-hatched young may have plenty 

 of accommodation on which to nest, and doubtless also for 

 the purpose of providing against a sudden riseof the water, 

 or the incessant wash of the tiny waves. When the colony 

 is invaded, the Gulls rise in clouds from their nests, and 

 commence a noisy clamour of remonstrance. The scene, 

 once witnessed, can never be forgotten, and may be 

 described best as a snowstorm, in which each flake is a 

 fluttering, noisy Gull. 



Range of egg colouration and measurement: 

 The eggs of the Black-headed Gull are usually three in 

 number, but four are sometimes found. They vary 



