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CIRCULAR 520. U. S. DEPARTMENT OF AGRICULTURE 



Terns 14 to 16 inches in length include the common tern (S. 

 hirundo) (fig. 6) and Forster's tern (S. forsteri), too nearly alike for 

 easy field identification. Both occur along the coast in migration. 

 The common tern breeds in New England, and both winter from the 

 South Atlantic coast southward. 



The Caspian tern (Hydroprogne caspia) and the royal tern (Tha- 

 lasseus maximus) are another pair of similar appearance. They are 

 larger birds, about the size of crows, with reddish-orange bills, the 

 royal having the tail about twice as deeply forked as the Caspian. 



Both may be seen 

 on the South Atlan- 

 tic coast in winter, 

 and both breed north 

 to Virginia. The 

 Caspian tern is seen 

 farther north in mi- 

 gration to and from 

 breeding grounds in 

 the northern interior. 

 The black tern 

 ( Oh Jidonias nigra ) , 

 easily recognizable 

 by its generally sooty 

 color, is rather rare 

 in spring on the At- 

 lantic coast. This 

 species may be more 

 numerous in late 

 summer but is then 

 in very different 

 dress. It breeds 

 chiefly inland. 



Terns seldom share 

 the carrion-e a t i n g 

 propensities of gulls 

 but capture their 

 prey alive, either on 

 the wing or, if in wa- 

 ter, by plunging. 

 Small fishes, 

 shrimps, and aquatic 

 insects are taken by 

 partial diving, and a 

 variety of insects by snatching them in the air. The black tern is 

 more pronouncedly insectivorous than the others. 



All the gulls and terns here mentioned are protected by Federal 

 law. 



The black skimmer (Rynchops nigra) (fig. 7) , a peculiar and strik- 

 ing bird, related to terns and as large as any American species, may 

 sometimes be seen about salt marshes. It breeds on beaches and bare 

 islands as far north as New Jersey and winters from Florida (occa- 

 sionally South Carolina) southward. It is dusky brown above, with 

 the forehead, lower parts, and the hind border of the wing feathers 



Figure 7. — Black skimmer. 



