54 



KEY TO GULLS (Cont.) 



17 Upper surface of wing with brown bar at base of secondaries (as 

 in Fig. 23a); tail white, banded with black; head with a dark spot 

 behind eye. BLACK-HEADED GULL, first year 



17' Upper surface of wing without brown bar at base of secondaries; 



tail white; head black (summer) OR white with dark spot behind eye 

 (winter). BLACK-HEADED GULL, adult 



18 Outer primary coverts with black; back of neck spotted with black; 

 in outer three primaries, leading edge as dark as tips. 



RED-LEGGED KITTIWAKE, first year 



18' Outer primary coverts pure gray; back of neck white; in outer three 

 primaries, only outermost as in 18, the other two are dark only 

 at tips. RED-LEGGED KITTIWAKE, adult 



19 Upper surface of wing with dark bar at base of secondaries (Fig. 23a); 

 hind neck (nape) with blackish collar; tail white with black band; in 

 outer three primaries, leading edge as dark as tips. 



BLACK-LEGGED KITTIWAKE, first year 



19' Upper surface of wing gray without dark bar at base of secondaries; 

 tail pure white; head white (summer) OR smudged with gray on hind 

 neck (winter); in outer three primaries, only outermost as in 19, 

 the other two are dark only at tips. BLACK-LEGGED KITTIWAKE, adult 



20 Upper surface of wing with bold black bar at base of secondaries 



(as in Fig. 23a); back feathers dull black with broad white edgings; 

 tail white with black band. LITTLE GULL, first year 



20' Upper surface of wing and back uniform gray; tail white; head black 

 (summer) OR white with gray smudge on hind neck and black spot 

 behind eye (winter). LITTLE GULL, adult 



21 Top of head, back and adjacent wing surfaces brownish-gray; tail 



white, banded with black. SABINE'S GULL, first year 



21' Back and adjacent wing surfaces uniform gray; head black (summer) OR 

 white with black spot behind eye (winter); tail white. 



SABINE'S GULL, adult 



22 Secondaries and tertials gray with conspicuous white tips. 



FRANKLIN'S GULL, adult 



