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Tuesday, 18 January 2011

Eye colour of Rainham SBG

I agree that the eye color is an issue (in fact the only thing I see that is wrong). Although I have seen a small percentage of (apparently pure) SBGU with this kind of dark mottled eyes in Japan, I think it would just be 1-2% at most that would show something this dark. In my experience, SBGU already start to show a pale eye by Oct of their second year and it's the norm in 2W birds. The dark eye might be a sign of vegae genes, since these two apparently hybridize extensively. I only saw one bird that had a paler mantle and was a presumed hybrid.

On trips to Honshu, I have had a bit more trouble with large gulls because of the greater mix of species and likely hybrids. I may have seen one much darker-backed bird on a 1992 trip, but it's certainly an exception to see 'blackish-backed' SBGUs in my experience. I don't really see that there is a lot wrong with the mantle color myself.

My experience in Hokkaido in 1997 was that SBGUs were remarkably uniform on the mantle and that a graellsii-like gray is a reasonable match.