Juvenile Yellow-legged Gull

I visited Cotesbach landfill site late yesterday afternoon and many gulls were loafing about in the quarry. Searching through them, I had found nothing of particular interest until I got to the very last gull.

Juvenile Yellow-legged Gull

As soon as I saw this bird I knew that it was a juvenile Yellow-legged Gull. It was a big individual with a thick neck, large head and a solid all black bill. The large pale head and chunky bill rule out LBB Gull and the tertial pattern rules out Herring Gull. Herring Gulls should have pale notches on the tertial fringes. Other supporting features include the greater covert pattern (barred on the lower ones and plain on the outer ones) and the dark mask around the eyes. Importantly, at least one of the scapulars is a 2nd generation type. It is not normal for juvenile Herring and LBB Gulls to start to moult their scapulars so early in the year. Also note the black outer tail band and the white upper tail coverts.

Having spent so much time studying the gulls at Shawell it is really satisfying to be able to ID birds like this. One of the reasons for putting in so much effort was to be able to ID the immature birds. Hopefully I'll find a juv. Caspian Gull soon.