Monday, 26 November 2012
'4th winter' argentatus or herring-LBB hybrid gull?
Some gulls are simply impossible to identify, especially when seen at range like this bird at Musselburgh on Saturday. Even with photographs I think this individual is impossible to pin down with certainty. Like a bird that I saw at Alnwickhill about a year ago its upperparts were a shade of grey in between typical argenteus Herring Gull and graellsii Lesser Black-backed Gull. For those in the know, that's just about bang on for Yellow-legged Gull or a dark northern argentatus Herring Gull or maybe an atypically dark mantled immature argenteus Herring Gull or maybe even a Herring x Lesser Black-backed Gull hybrid! Or could it be a scarily pale LBBG? So lots of options...
The above shot shows the bird in question centre right. The upperpart shade was consistently darker than the other Herring Gulls such as the bird on the left.
This shot shows the mantle shade of Herring Gulls in the foreground, a slightly darker Common Gull on the right and the slightly darker mystery gull at the rear. The white tertial skirt and elongated Lesser Black-backed Gull-like appearance were noticeable in the field.
With the Alnwickhill bird last year, which admittedly I saw at much closer range, I suggested an immature dark northern argentatus. Saturday's bird, on the other hand, maybe looked much more like a pale Lesser Black-backed Gull in structure and it possibly seems to fit the argentatus x fuscus Herring x Lesser Black-backed Gull hybrid option most closely. But, to be honest, who knows?... After all the flight shots below have a look of northern argentatus about them. Help! Any ideas?