334 KEY AND DESCRIPTION 



in winter (the only season the bird is seen in the United 

 States) mainly white, with a varying number of blackish marks 

 on the back and sides of head; back and wings dark pearl-gray; 

 under parts, except throat, white ; first primary black, with the 

 inner half of the inner web white except at the tip ; the next 

 three tipped with white; the secondaries tipped with white. 

 In summer the whole head and throat are slate-colored. 



Length, \?,\; wing, lOJ (10|-11^); tail, 4|, forlied, |; tarsus, IJ; 

 culinen, 1. Arctic regions; soutli in winter to New Yorl?, Great Lakes, 

 and Great Salt Lakes ; casual in Kansas and the Bahama Islands. 



FAMILY LXL SKUAS AND JAEGERS (STERCORARIiD^) 



A small family (6 species) of mainly dark-colored, rather 

 long-tailed, long-winged, swift-flying, swimming birds, with 

 the central tail feathers abruptly projecting beyond the others. 

 These birds are hawk-like in the form of their bills ' 

 fe^\--2>v ^'^'^ ^^ their actions ; they chase the terns and smaller 

 ^^5=^^ gulls and snatch from them the fish and other prey 

 ^ which they have caught. Although good swimmers, 



they seem unable to dive. The bill has a large, cere-like cover- 

 ing to the nostrils. 



Key to the Species 



* Wing over 15 long ; culmen over 1| ; tarsus, 2i-2| 1. Skua. 



* Wing, 13^-15 long ; culmen under 1|; tarsus, 1|-2| 



2. Pomarine Jaeger. 



* Wing not over l^ long ; tarsus not over IJ ; central tail feathers acute. 



(A.) 



A. Scaly cere over the nostril more than half the length of the cul- 

 men ; central tail feathers projecting less than 5 inches heyond 

 the others 3. Parasitic Jaeger. 



A. Scaly cere less than half the length of the culmen ; central tail 



feathers in the adult projecting over 6 heyond the others 



4. Long-tailed Jaeger. 



1. Skua (35. MegaUstris sMa). — A northern, large, stout- 

 bodied, dark-brown sea-bird, with a nearly even tail having all 

 feathers broad at tip; the under parts are somewhat lighter 

 than the upper ones, and the neck is streaked with whitish. 



