254 THE BIRDS OF THE NORTH ATLANTIC 



on the Pacific side except in Central America, where, like the Sandwich tern, it 

 crosses the isthmus from the Caribbean Sea. The head, beak, and legs are black 

 and the tail is grey. On account of its cry of " ya-ha, ha, ha," it is known in many 

 places as the laughing tern. 



The largest European member of the group is the Caspian tern 

 {Hydroprogne caspia), which is 20 inches long, with a stout reel beak, 

 occasionally horn-coloured at the tip, short black legs, and a short and not deeply 

 forked white tail. Nesting in the Baltic and the inland seas of Asia, as well as on 

 both coasts of North America down to Florida and California, in the Persian 

 Gulf, and in Australia and New Zealand, it does not occur on the Asiatic side 

 of the Pacific. 



Among the Laridce of the North Atlantic are the little gull 



Gulls. . 



(Larus minutus) and the black-headed gull (L. ridibundus), both 

 of which breed in northern Europe and Siberia, and have a wide range of 

 migration. 



A third kind, the herring-gull (L. argentatus), rarely occurs in the Baltic, but 

 is common on the shores of the North Sea, and, like the black-backed species, is a 

 common British breeding bird. Attaining a length of 23 inches, it has the back 

 and wing-coverts bluish grey, and the primaries black with white tips and spots 

 and a grey wedge down their inner webs, which increases in width on the hinder 

 feathers till the black is reduced to a band near the tip. The head is white spotted 

 with grey and the beak yellow, while the legs are flesh-coloured. This gull 

 inhabits both shores of the North Atlantic, as well as the eastern side of the 

 North Pacific, and is most common near the mouths of rivers. It lives chiefly on 

 the shore, where it feeds on the eggs of other birds, molluscs, crustaceans, and 

 dead fish. Living fish, however, also form a portion of its diet, and in capturing 

 these the bird will often dash down with such force as to dive a couple of feet or 

 more into the water. It is said to prey on the shoals of herring as they pass along 

 the coast, and from this habit derives its popular name. The nest, which is always 

 near the sea, may be either on flat sand, sand-dunes, or amid rocks, but on the 

 American side is frequently in trees or bushes. Sometimes it is a small and loosely 

 built structure, but it may be large and built of grass and seaweeds lined with 

 stalks. 



The other sea-gulls of the North Atlantic have their chief breeding-places in 

 the far north, and may therefore be more appropriately noticed among the birds 

 of the Arctic Ocean. 



The petrels and their allies differ from the gulls (to which many 

 of them present a superficial resemblance) by having the nostrils 

 taking the form of a pair of tubes on the upper surface of the beak, which is 

 generally hooked. These birds are more decidedly oceanic, or pelagic, than the 

 gulls, and although met with in all latitudes, are more numerous in the tropics, 

 and especially in the Southern Hemisphere, than in the north. During the breeding- 

 season they resort to unfrequented coasts, where they nest either in cavities of rocks 

 or in holes in the ground dug by themselves. At this season they feed much more 

 on land than at other times, a large portion of their nutriment consisting of carrion. 



The members of the group met with in the North Atlantic are few in number 



