GULLS. 295 



the world. Many of the species, besides visiting the 

 shores of Northern Europe and Arctic America, extend 

 their flights to far southern latitudes, and some appear 

 to live constantly on the open sea, except when they 

 visit the shore in the breeding-season. All are remark- 

 able for the strength of their flight, and the easy grace 

 of their motions as they soar or glide through the air 

 with a scarcely-perceptible movement of wing ; but 

 some are much more active than others. Their form 

 is elegant and well-proportioned : some, as the Terns, 

 resemble swallows in shape and rapidity of flight ; and 

 others, as several of the Gulls, seem analogous to pigeons. 

 Almost all undergo remarkable changes of plumage at 

 different ages, and some have also an annual change, the 

 colours at the breeding-season becoming darker. This 

 change rapidly takes place, without any moulting, the 

 feathers of the head, which are originally white, gradual- 

 ly assuming a dark-brown or black colour. These birds 

 are mostly voracious feeders, seizing indifferently on 

 dead or living animal substances found floating on the 

 sea, or thrown up at the recess of the tide. Large flocks 

 both of Gulls and Terns are then busy with the Mollusca 

 and Radiata on the sands ; and at other times they may 

 be seen hovering over the water, on the watch for any 

 floating animal substance. This they perceive from a 

 considerable height, and secure by a rapid descent and 

 pounce ; sometimes by merely curving down and skim- 

 ming the surface ; at other times, by closing the wings, 

 and dropping suddenly under water. Both sexes in the 

 Gulls have similar plumage ; but the males are known 

 by being of larger size than the female. Their cry is 



