A possible Yellow-legged Gull (Larus michahellis)
on South Beach, Chatham (Cape Cod), Massachusetts
, USA 

14 September 2006

 I found the gull illustrated below late in the day and even at a considerable distance it caught my eye immediately, due in part, no doubt, to the company it was keeping (see 1st photo). It was Herring Gull sized, but with a darker gray mantle (though considerably lighter than the adjacent adult Lesser Black-backed Gulls). The legs were bright pinkish, with a yellowish tinge, much brighter and lacking the gray tones of the legs of nearby Herring Gulls. The bill was heavy and thick with a distinct gonydeal angle. The iris was yellow, but I could not see the color of the orbital ring (nor is it visible in the photos).

 The bird appears to be molting from 3rd Summer into 4th Winter/Adult plumage, though I'm somewhat puzzled by the state of molt. The bill was adult-like (i.e., no black), but the rectrices retain some black on the tips. The innermost primaries (P1-P6?) appear new, P7&P8 are not evident (?growing?), while P9&P10 appear old. There is a small white mirror on the tip of P10. However, the secondaries show extensive black and apparently are all old (why no new secondaries when half of the primaries are new?). Perhaps I'm mis-interpreting the photos.

 The following photographs were taken with a Nikon Coolpix 995 digital camera through a Leica Televid 77 telescope w/20-60X eyepiece (first two photos) and a Canon 20D with a Canon 100-400mm IS lens (last four photos). The light was very poor (just before sunset on a cloudy day), so these were taken at a high ISO (400 & 800), resulting in considerable grain and noise. I've adjusted the brightness/contrast, reduced the noise (with Noise Ninja software), and sharpened the images.

 In the first two photos, the subject bird is on the left rear (partially obscured by a Lesser Black-backed). In the third photo, it is the rear bird.

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Blair Nikula