FAMILY STERCORARIIDA. —SKUAS AND JA2GERS. 33 
FAMILY STERCORARIIDA:. 
Skuas and Jegers. 
Nostrils, separate, and not tubular; bill, with cere; front toes, palmate 
(full webbed); hind toe, small, but always present; end of upper mandible 
(unguis), swollen, and somewhat rounded; back and wings, 
always dark, sometimes sooty, sometimes barred with brown; 
tail, never white or gray, usually very dark; middle tail feath- 
ers, longest. The cere (hard skin-like covering on base of upper 
mandible) will distinguish these birds from Gulls. 
* Group I. Wing, 11 to 15 inches long. 
Underparts, not entirely pure white; bill, over 1.353 tarsus, over 1.80; middle tail 
feathers, not pointed ; plumage, sometimes dark brown; sometimes mixed gray, brown, and 
white. Stercorarius pomarinus. Pomarine Jeger. 
See No. 19. 
Bill, under 1.353 tarsus, under 1.80; middle tail feathers, pointed; base of unguis 
to frontal feathers less than length of unguis; shafts of primaries, yellow white. 
Stercorarius longicaudus. Long-tailed Jager. 
See No. 21. 
Bill, under 1.355 tarsus, under 1.80; middle tail feathers, pointed; base of unguis to 
frontal feathers, greater than length of unguis; shafts of primaries, yellowish white. 
Stercorarius parasiticus. Parasitic Jaeger. 
See No. 20. 
* Group 2. Wing, over 15 inches long. 
Bill, with cere; general color, dark brown, more or less streaked with light brown: a 
patch of white at base of primaries. Megalestris skua. Skua. 
See No. 18. 
* For directions for measurement, see page 9. 
