KEY TO FAMILIES. 



MATEK UIRDS. 



13 



Nostrils, sepanitc not tubular; bill, with cere (a horny or skin-like covering on base of 

 upper mandible) ; hind toe, sometimes very small; end of upper mandible (unguis), swollen 

 and somewhat rounded; baek and wings, always dark, sometimes sooty, sometimes barred 

 with brown; tail, never white or gray, usuallv very dark ; middle tail feathers, longest, 



but only very long in ailult birds, sometimes only slightly long(M- than rest of tail feathers in 

 immature birds; in brown plumages, the axillars (feathers extending from armpit) are 

 heavily l)arred, l)ro\vii and white; in other plumages, the axillars and under wing coverts are 

 sooty !)rown or dark slaty brown. Family STERCORARIID/E. Skuas and Jaegers. 



See page 34. 



m 



■:\ 



Nostrils, separate not tubular; bill, without cere ; bind toe, sometimes verv small; upper 

 mandible, curved; unguis (end of bill), not swollen; middle tail feathers, about equal in 

 length to the others; tail, rarely dark, although sometimes tipped with black or brown; 

 axillars and under wing coverts, white or gray, sometimes with narroio grav lines or taint 

 wavy bars. 



Family LARID/E. Subfamily LARIN/E. Gulls. 



See page 30. 



re^ 



Nostrils, separate nol luliular: hind toe, somclinies vei-y small : upper mandible, nearly 

 sti-aiglit, not hooked or dccidfdly iiMimii'd near lip: nnlcriail Iciihers, u^iially longer liian 

 middle feathers. Family LARID/E, Subfamily STERNIN/C. Terns. 



See page 41. 



I'.ill. 

 below. 



lik.- blad.- ol 



knife, the undii- mandible the longer: plumage, black above, white 



Family RHYNCHOPID/E. Skimmer*. 



See page lo. 



