LARID^E : Gulls and Terns 



COMPARISON OF WING-TIPS OF ADULT 

 GULLS; DRAWN TO SAME SCALE 



KITTIWAKE 



Always all black, this extending on first 

 primary, on upper side only of narrow 

 outer web, and not visible from below. 



RING-BILL 



In rare cases mirrors are absent, or a 

 small mirror on second feather; none in 

 the second year plumage. 



SHORT-BILL 



Mirrors relatively largest of all the 

 Gulls, but vary much in size ; present in 

 second year, but small, or on outer feather 

 only. 



CALIFORNIA 



Note relatively large area of black. 

 Sometimes the large mirror covers the 

 entire tip. Third year birds have mirror 

 on first feather only, generally small. 



HERRING 



Black area relatively much smaller than 

 in the California; not extended on edge 

 of wing. In flight overhead shows least 

 black in proportion to wing area. 



WESTERN 



Note extensive black which reaches in a 

 wedge to body. Occasionally a small mir- 

 ror on second primary, and rarely none on 

 either. Third year specimens with or with- 

 out mirror. 



GLAUCOUS-WING 

 Gray wing-tips, so light that the white 

 mirror is hardly visible. Against the sky 

 the wing appears wholly white. 



