KEY TO FAMILIES. WATER BIRDS. 



13 



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

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

 and somewhat rounded; back aud wings, always dark, sometimes sooty, souietimes barred 

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



[ 



but only very long in adult birds, sometimes only slightly longer tliau rest of tail feathers in 

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

 heavily barred, brown and white; in other plumages, the axillars and under wing coverts are 

 sooty brown or dark slaty brown. Family STERCORARllD/E. Skuas and Jaegers. 



See page 34. 



^ 



Nostrils, separate not tubular ; bill, without cere ; liind toe, sometimes very 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 l)rown; 

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

 wavv bars. 



" Family LARID/B. Subfamily LARIN^. Gulls. 



See page 36. 



,-t^. 



Nostrils, separate not tubular ; hind toe, sometimes very small ; upper mandible, nearly 

 straight, not hooked or decidedly rounded near tip: outer tail feathers, usually longer than 

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



See page 41. 



Bill, like blade of a knife, the under mandible the longer; plumage, black above, white 

 below. Family RHYNCHOPID/E. Skimmers. 



See page 45. 



