01 May 2024

April 2024 Quiz


California. January.

Age: 1st cycle in what appears to be complete juvenile plumage.

Identification: This juvenile is clearly a member of the large white-headed gulls (as opposed to smaller tern-like or hooded gulls). Some Slaty-backed Gulls can approach this look, especially the plain pattern to the greater coverts, paired with pale bases to the median coverts showing pointy dark tips. However, the massively thick bill, large head with proportionally small eye placed high on the face, call to mind Western and Glaucous-winged. The primaries are too dark for Glaucous-winged and too pale for Western (which doesn't show this extensive pale edging). The neatly pattern coverts (which we've noted can be found in Slaty-backed at this age) are also expected in hybrid Western x Glaucous-winged, which is what this individual was identified as. Herring x Glaucous-winged Gull is another taxon to consider, which often shows a slighter, Herring-like build, averages a thinner bill and streakier head at this date.