STERCORARIID.E THE SKUAS AND JAEGERS. 211 



FAMILY STERCORARIID.33. THE SKUAS AND JAEGERS. 







CHABACTEES. Covering of the maxilla, not entire as in the Laridce, the basal half being 

 furnished with a saddle-like horny cere, the lower edge of which overhangs the nostrils; 

 toes fully webbed, the claws strongly curved and sharp ; posterior side of tarsus roughened; 

 tail more or less graduated, the middle pair of feathers projecting more or less beyond the 



rest. 



The Family Stercorariidce is separated from the Laridce chiefly 

 on account of the peculiar bill, which shows a not distant re- 

 semblance to that of some raptorial birds. The species are all 

 predatory in their nature, being, in fact the most predaceous of 

 sea-fowl veritable "robbers of the sea." The smaller Jaegers 

 (genus Stercorarius) pirate upon gulls and other sea-fowl, thus 

 earning the common names of "gull chaser," "jaeger" (hunter), 

 etc.; while the larger skuas (genus Megalestris), also beat along 

 the shores or even over the land, and besides forcing gulls and 

 other birds to disgorge or relinquish their food, prey on various 

 birds much in the manner of hawks and falcons. Indeed, it is 

 said that at Kerguelen Island, in the Antarctic Ocean, the Meg- 

 alestris antarcticus keeps strictly to the land, where it is very de- 

 structive to ducks and other water-fowl. 



Only two genera are recognized, their characters being as fol- 

 lows: 



1. Megalestris. Size large (in bulk equal to the largest gulls), and form robust; depth of 



bill at base eaual to not less than half of the length of the upper mandible, measured 

 along the side; tarsus shorter than middle toe with claw; tail short, nearly even, the 

 middle pair of feathers scarcely projecting beyond the rest ; color dull brownish, some- 

 times streaked (never barred) with paler, the base of the primaries with a whitish 

 patch. 



2. Stercorarius. Size medium or rather small (not exceeding the medium-sized gulls), and 



form more slender and graceful; depth of bill at base less than half the length of the 

 upper mandible, measured along the side; tarsus decidedly longer than middle toe 

 with claw; middle rectrices in the adult projecting far beyond the rest; color plain 

 slaty or dusky, often varied with white or yellowish, in the adult; dusky barred with 

 paler in young; no white at base of primaries. 



