01 May 2022

April 2022 Quiz

British Columbia. March

Age: This is a larger four-cycle gull. The marked tail, faintly marked primary coverts and bill pattern suggest a 3rd cycle type.

Identification: The paler pigment on the outer primaries immediately evokes thoughts of a white-winged species (e.g., Iceland and Glaucous-winged). Glaucous Gull never shows mirrors as seen on the tenth primary, never has this much contrasting pigment on the primary pattern or tail, and the bill pattern often yellow by now. This is a broad-winged bird with apparent smudged head and neck markings. The eye appears relatively small and dark, but the bill is decidedly thick, which is very typical of Glaucous-winged. A fair number of Glaucous-winged Gulls can show this delayed bill pattern into 3rd cycle and this is what our March bird was identified as. Thayer's is ruled out by the lighter gray wingtips (although perhaps not unheard of in some variants), and particularly the larger bill and small-ish eye.

3rd cycle type Glaucous-wingeds can show this contrasting pigment on the outer primaries and this is not necessarily indicative of outside influence (i.e., hybridization with Herring or Western Gull).