GULLS AND TERNS 27 



were plentiful, every flock had adults in nuptial plumage, showing 

 that the young are not without experienced leaders on the return 

 north." 



GENUS XEMA. 



62. Xema sabinii (Sab.). SABINE GULL. 



Bill gull-like, tail conspicuously forked, the feathers rounded, not nar- 

 row and pointed at ends. Adults in summer : head and upper 

 neck dark plumbeous, bordered below by a black collar ; man- 

 tie slaty gray ; tail and middle of wing white ; outer quills- 

 Fig. 4G. black, with inner webs and tips white ; under parts white ; 

 bill black, tipped with yellow. Adults in winter : head and 

 neck white, with dusky on ear coverts 

 and back of head. Young : like winter 

 adults, but mantle brownish, feathers 

 with buffy or grayish edges ; tail with 

 a subterminal black band, white tip Fi S- 47 - 



and base; bill black. Length: 13-14, wing 10.10-11.15, bill 1.00, tail 

 4.50-5.00, fork .60-1.00 deep. 



Distribution. Arctic regions of North America ; south in winter to 

 Peru. Not common in the United States, but recorded from many scat- 

 tered localities. 



Eggs. Laid on the ground, or on a few grass blades and stems ; 2 to 5, 

 olive, indistinctly spotted with brown. 



GENUS GELOCHELIDON. 



63. Gelochelidon nilotica (Hasselq.). GULL-BILLED TERN. 

 Bill stout, depth at base equal to one third of its length ; tail forked. 



Adults in summer : top and back of head black ; upper parts light pearl 

 gray ; lower parts white ; bill black ; feet and legs blackish. Adults in 

 winter : head and neck white ; ear coverts and spot in front of eye gray. 

 Young : similar to winter adults, but upper parts washed with buffy and 

 sometimes streaked with dusky. Length: 13.00-15.25, wing 11.75-12.25, 

 bill 1.40, tail 5.50, forked for 1.50-1.75. 



Distribution. Almost cosmopolitan. In America from Brazil to Massa- 

 chusetts along the Atlantic coast, and both coasts of Mexico and Central 

 America ; rare inland. 



GENUS STERNA. 



General Characters. Bill slender and sharp ; tail deeply forked, the 

 outer feathers narrowed or sharp-pointed ; wings very long and slender. 



KEY TO SPECIES. 



1. Black feathers of crown elongated into a crest. 



2. Size large, wing 14-15 maxima, p. 28. 



2'. Size smaller, wing 12.40-12.50 elegans, p. 29. 



1'. Head not crested. 



2. Size large, feet black caspia, p. 28. 



2'. Size small, feet red, orange, or yellow. 



3. Crown and forehead black in summer adults, wing over 9. 



4. Outer web of outer tail feather white . . . forsteri, p. 29. 

 4'. Outer web of outer tail feather dusky. 



5. Bill orange, with black tip . . ... . hirundo, p. 29. 



5'. Bill carmine, without black tip ... paradisaea, p. 30. 

 3'. Forehead always white, wing under 7 ... antillarum, p. 30. 



