of the United States. 353 



Sexes perfectly similar in color. Female a little smaller. 

 Young differing from the adult, but only before their first or 

 second moult. Moult twice in the year, changing the colors 

 of the head only. Plumage silky. Colors white, with bluish 

 tints, with some black; or black with some white. Young 

 skirted with blackish, ferruginous, he. 



Live in small flocks near water, especially on the sea. Fly 

 almost continually high in the air, playing in different direc- 

 tions, or skim the surface of the water, alighting occasionally 

 on the beach, on rocks, or naked poles, but hardly ever on 

 the water : swim awkwardly, and never from choice. Feed on 

 living animals, principally fishes, which they catch by turning 

 rapidly near the surface of the water, or by flying at a mode- 

 rate height, and darting headlong upon their prey as soon as 

 discovered ; the larger and more powerful species prey also 

 on the young of water birds and their eggs : some do not 

 avoid swallowing insects as they fly along, and the weaker 

 pecies feed entirely upon them. Lay socially on the ground, 

 sandy beaches, or on rocks, without the least preparation : 

 eggs few, 2 — 4; sedulously protect their offspring. Voice 

 sharp, shrill, often repeated, especially in fine weather, when 

 soaring. 



Widely spread over the waters of the globe. Closely 

 allied to the following genus, into which the}' pass insensiblj'. 

 Analogous to the Swallows. 



* White, back wings and tail, pearl-gray. 



284. Sterjta cayana, Lath- Bill elongated, stout, orange ; 

 quill shafts white ; tail not much forked ; tarsus one inch 

 and a quarter long, black ; webs entire. 



Summer plumage, whole crown black : winter, hind head 

 only marked with black. 



Cayenne Tern, Sterna cayana, Nob. Am. Orniii. pi. 



Inhabits the tropical seas of America : common on the 

 coasts of the southern states. 



