51 



KEY TO GULLS 



1 Outer 5 primaries wholly white. 23 

 1' Outer 5 primaries not wholly white. 2 



2 Outer 5 primaries white with black tips; body plumage white with 



black spots. IVORY GULL, first year 



2' Outer 5 primaries not white with black tips. 3 



3 Wing length <325 mm. 4 

 3' Wing >325 mm. 24 



4 Wing >295 mm. 5 

 4' Wing <295 mm. 8 



5 Outer three primaries uniformly blackish (check inner webs 

 carefully). 15 



5' Outer three primaries with white or gray areas. 6 



6 Outer three primaries extensively white, with black tips and dark 



(gray to black) trailing edges (Fig. 22). 17 



6' Primaries not as above. (KITTIWAKE) 7 



Figure 22. Outer three primaries of the Black-headed Gull. 



