SEA-CLIFFS IN NESTING TIME 131 



of the sea-cliffs, since they prefer to nest on more level 

 ground ; but they are usually found in close company with 

 various species of gulls, to which family they are closely 

 related. These varied species give a wonderful wealth of 

 interest to the bird life of our rockier coasts in spring ; 

 and in certain favourite haunts their numbers are almost 

 incredible. 



Broadly speaking, it is the west and north that have 

 most of these sea-birds, and the east and south that are 

 poorest in them. This naturally follows from the com- 



SKUA AND GULL 



parative flatness of the south-eastern coasts of this kingdom, 

 and from the greater density of their population. On flat 

 and marshy shorelines the place of guillemots and cormo- 

 rants and most kinds of gulls is taken during the breeding 

 season by shore-birds such as the ringed plover, and by 

 the terns. But the black-headed gull is an exception to 

 the general habits of its family, and prefers the more level 

 parts of our coasts, as well as similar sites on inland lakes 

 and marshes. In this respect it approximates to the habits 

 of the terns. Of the true cliff-breeders the most persistent 

 in clinging to the south and south-east coasts is the herring 

 gull. It still nests in considerable numbers on the chalk 

 cliffs of Kent and Sussex, and at various points westward 



