324 KEY AND DESCRIPTION 



outer web and tips of primaries blackish, and the rest of the 

 plumage white. In the breeding season, there is a black cap, 

 but during the rest of the year the head is streaked black and 

 white. This is much like the last species, but in all ages and 

 seasons, the royal tern can be distinguished by the inner web of 

 the primaries which is white, at least on the inner half. This 

 is a common, strong, and powerful tern of the southern coasts, 

 and is nearly as large as any gull ; so the student may distin- 

 guish the gulls from the terns by noting the difference in the 

 position of the heads of the species when in flight. The gull's 

 head is in line with the body, the tern's points toward the earth. 



Length, 19; wing, 14J (14-15); tail, 7, forked, 3]; tarsus, If; cul- 

 men, 2^ ; America, chiefly tropical ; breeding north to Virginia ; wander- 

 ing to Massacliusetts and the Great Lakes, and wintering from the Gulf 

 coast southward. 



4. Cabot's Tern (67. Stirna sandvicdnsis anifldvida). — A 

 southern, crested, pearl-gray-backed, white-bellied tern, with a 



large, yellow-tipped, black 

 bill, and black feet. In the 

 breeding season, the whole 

 top of the head and crest 

 is black, but during the rest 

 of the year the crown is 

 white, somewhat spotted 

 with black, and the crest black streaked with white. The 

 young has the pearl-gray back spotted with blackish, the slaty- 

 gray tail short, and the bill nearly all black. (Sandwich Tern.) 



Lengtli, 15; wing, 12i ; tail, 6, forked over 2 ; tarsus, 1 ; oulmen, 2-|. 

 America, chiefly tropical ; breeding along the Gulf coast, and along the 

 Atlantic north to South Carolina ; wandering north to New England, and 

 wintering from Key West to Central America. 



5. Forster's Tern (69. St4rna fbrsteri). — A medium-sized 

 tern, with wings and back pearl-gray, rump and all under parts 

 white, and bill blackish at tip and dull orange at base. The 

 tail is light colored, and the inner webs of the tail feathers are 

 always darker than the outer ones. In summer, the whole top 



