Thursday 5 July 2012

The Danish gull versus different Thayer's Gulls from Japan

The pulled out face, rather flat forehead, slightly elongated narrow bill and overall head and bill profile have been argued to give the bird a look unlike the idea many have of the Kumlien’s/Thayer’s group. But as stated by Kirk Zufelt one of the biggest misconceptions in gull identification is the issue of structure in Thayer's Gull. Certainly lots of Thayer's have a rather petite rounded head and most of these are obviously females. Male Thayer's are on the other hand often robust and often more so than some Herrings especially the females. The flattish headed look is not infrequent in a robust male Thayer's. The bill does tend to be a bit more petite and thinner than an equivalent sized Herring Gull which is also the case in the Danish gull. Its structure and plumage are all well within range as have been proven in discussions and previous post. The best and simplest solution to the Danish gull is a juvenile male Thayer's Gull.

Please not how the head shape changes in several of the Thayer’s from Japan depending their posture and behaviour.

Thayer’s Gull: from top left to right bottom1: 4.2.2012, Hvide Sande Harbour, Denmark, Kent Olsen; 2-3: (same individual) 27.12.2008, Coshi, Japan, M. Ujihara; 4: 28.12.2008, Coshi, Japan, M. Ujihara; 5-6: (same individual) 8.12.2008, Coshi, Japan, M. Ujihara; 7: 4.2.2012, Hvide Sande Harbour, Denmark, Kent Olsen; and 8-9: (same individual) 28.12.2008, Coshi, Japan, M. Ujihara.

I do not think the head of the Danish bird is neither that abnormally flat, nor its bill unusually big. Perhaps my assessment of shape is severely lacking, but I would not say that the head of the Danish bird looks neither flatter than any of these six Japanese examples, nor that its bill looks bigger. For anyone who wants to check, the five examples photographed by Masashi Shinjo in Choshi can be found in their proper context here, respectively: here, here, here, here and here.

Thayer’s Gull: upper row: 1-6: 4.2.2012, Hvide Sande Harbour, Denmark, Kent Olsen; lower row: 7-12: six different adult or subadult Thayer's Gulls from Japan, Peter Adriaens & Masashi Shinjo.