48 TEKXS. 



f. Fork-tailed Gulls. Xema. 



Size, small ; tail, prominently forked, fig. 57 ; mantle, 

 much darker than in e. 



SABINE'S GULL, X. SABINA. 13.50; head and up'per 

 neck, plumbeous, bordered below by a black collar; mantle, 

 dark bluish-gray; 

 primaries, black, the 

 five inner more or 

 less marked with 

 white ; plumage, 

 otherwise white ; bill 

 black, tipped with 

 yellow. In winter, 

 head white with ear- 

 coverts and back of 



head and neck, 



plumbeous. Young, , B 1. 1-6. 



with the mantle, brownish-gray; tail, with a broad black 



band near end, and this is narrowly tipped with white. 



Breeds in the Arctic regions ; south in winter very rarely to 



Mass., N. Y.. and the Great Lakes. 



C. TERNS, Sternidae. 



Birds of varying sizes but more slender and graceful in 

 form than in B, with more pointed bills which are never 

 hooked; angle of lower mandible, not so decided as in 13, 

 plate 4 ; wings, very long and pointed, 1st primary, longest ; 

 secondaries, short; feet, rather small, not well fitted for 

 walking. Occur on ocean coasts and estuaries and on bod- 

 ies of fresh water. Nests, placed on sand, rocks, or occasion- 

 ally on bushes; eggs, 1 to 5, similar tolB. Procure their 

 prey, which usually consists of small fishes, by diving direct- 

 ly downward, often becoming wholly submerged. In flight 

 the bill is frequently pointed downward ; in alighting the 

 wings are often stretched upward before folding, much as is 

 done by many waders. 



