A particularly tricky white-winged gull

This morning I paid my usual weekly visit to Rushton Landfill. In recent weeks it has been pulling in up to 4,000 gulls, including several Caspians, and the chances of finding either Glaucous or Iceland has been on the cards for some time, given the current higher than usual numbers of both species present in the UK this winter.

Gulls frequently loaf in good numbers on adjacent fields and one of the favourite gathering places is the field immediately north of the landfill, at Storefield Lodge Farm. It was here that, going through the assembled flock this morning, I picked out a first-winter Caspian and, at last, found a white-winged gull. My immediate reaction was forth-winter Glaucous as it seemed quite large, looked a little dingy and had a blackish subterminal band on the bill – otherwise it was a winter ‘adult’ with fairly well-marked head streaking, which extended to the neck and upper breast, albeit rather faded. I duly broadcast the news and then went back to getting a proper look.

Next to Lesser Black-backed and Herring it appeared marginally larger, although the bill was not long but the head appeared rather flat-crowned. Given size and proportions I quickly came to the conclusion it must be a small female Glaucous. Over the next couple of minutes I took a few long distance digiscope shots before the bird disengaged itself from the flock and flew a few metres closer. Any potential prolonged observation was quickly cut short at this point, however, as the explosive gull-scarer went off on the adjacent landfill and all the gulls took to the air and quickly dispersed. Despite a search of neighbouring fields I failed to relocate the gull. It was only after later examination of the images I managed to obtain that nagging doubts about the bird’s identity crept in. Although in the first three images reproduced here the bird appears large and ‘mean-looking’ (= Glaucous) in the last of the series of images the true proportions are visible. It lacks the truly hefty proportions of Glaucous Gull, appears attenuated with a long primary projection and has a more rounded head and relatively small, short bill, bearing a resemblance to a Common Gull. This all adds up to it being an Iceland Gull with the size and sometimes flattish, sloping forehead suggesting a ‘butch’ male.