78 



NATURAL HISTORY OF BIRDS. 



good in most of the forms, it is by no means reliable, since we have gulls with deeply 

 forked tails, and both gulls and terns in which the tail is wedge-shaped or graduated. 



The predominating color of the adult members of this sub-family is white with a 

 gray mantle, varying in shade from the most delicate pearl gray to dark blackish slate, 

 or nearly black, and the head is often more or less marked with black in summer. 

 The seasonal change is not great, and affects chiefly the color of the head, which, in 

 species with black hoods, turn white in winter, while the white-headed gulls usually get 

 that part streaked with dusky during the same season. There are, however, several 

 forms, both among gulls and terns, which are more or less dusky. The bills and feet 

 are usually brightly colored, yellow or red, and the sexes are alike in color. The 

 young ones, however, are very different from the adult, being mostly of a brownish- 

 gray, spotted or streaked with dusky, and with dusky wings and tail, the bill also 

 being dark. 



The gulls inhabit the oceanic shores and inland lakes alike, though most species 

 are truly mai'ine, or nearly so, and as they are distributed all over the world, their 



FIG. 33. Hydrocolceus ridibuiulus, black-headed gull. 



graceful form is familiar to everybody, whether he dwells near the coast or far in the 

 interior. Our own shores of the two .oceans are thickly populated by their noisy crowds, 

 and on our large inland waters numerous colonies rear their black-speckled brood. 

 We therefore need only refer to the accompanying full-page cut, to recall to our 

 readers the fascinating view of a gull rookery with its ceaseless uproar, caused by the 

 screaming and quarrelling birds, overnoising even the thunder of the surf. The black- 

 hooded gulls, of which the cut illustrates a characteristic and well-known Old World 

 representative (Hydrocolceus ridibundus), are still more clamorous, and their voice 

 more penetrating, than that of their larger relatives (.Z/arws), resembling, in fact, that 



