Tough Gull ID

First Winter Great Black-Backed Gull?

or

First Winter Lesser Black-Backed Gull?

There have been quite a few Lesser sightings in the area, so it wouldn't be a shock. The gull did appear to be "large" to me though, I was at a considerable distance.

- Luke

Based on size from looking in 3 books I would say a Great Black-Backed Gull. That said I am no expert but love a challenge!

This is a pretty tough call Luke with no reliable size reference and the amount of detail visible. The lack of streaking in the breast make me think Great Black-backed, but the view is not very definitive.

As Matt says, the angle isn't very good. Normally I'd go by bill size; the Greater has a real honker in comparison to the Lesser. But the angle makes that awkward. The darker mantle and the white edging on the coverts and secondaries make me think Lesser. I've spent a lot of time with Olsen and Larrsson trying to work this out, and I'm going to say First Winter plumage Lesser Black-backed Gull.

My instant reaction was Greater Black-backed Gull before I read your notes. We get both species in large numbers in the UK, so I have a lot of experience of them. Putting aside the size of the bird, the clean head, weakly marked breast and extensive pale edges to the tertials are all indicative of Greater Black-backed. The bill also looks proportionally thick and heavy.

1st year Lesser Black-backed should have a much darker head and breast, very narrow, pale tertial edges and a much less heavy looking bill.