Gulls

Blue ring with an orange 3-alpha code (on one leg) and a BTO metal ring (on the other leg).

note 1 : a single bird of this species was colour ringed on December 16th 2007.  It was seen several times subsequently around the UK.

note 2 : this is the account of the first sighting and subsequent ringing:

On Dec 15th I saw a gull which I immediately knew had a plumage combination that I had never previously seen at Gloucester landfill site. It was the size of a largish, stocky Herring Gull, but the head, neck and underparts were a solid greyish brown, something similar to what one would expect to see on a first-winter American Herring Gull, while the upperparts were pale grey, with faint brown markings, especially on the tertials, features appropriate for a third-winter bird. The primaries were grey, with white tips, a characteristic associated with Kumlien's Gull. I managed to get three reasonable digiscoped pictures, before the bird was disturbed, and flew away. That evening I studied the literature, and came to the conclusion that the gull showed several features of Glaucous-winged, but nowhere on the internet could I find a picture that matched it. I read that this species hybridises freely with at least three others, so assumed that my bird was a hybrid. Members of the Severn Estuary Gull Group were cannon netting the following day (16th), and by a sheer fluke trapped the gull, since no one had seen it in the trapping area before the net was fired. We now had the opportunity to take measurements and digital pictures. While being handled the gull shed a couple of feathers, which have been kept for possible analysis. A BTO metal ring was fitted to the right leg, and a blue plastic ring, inscribed with three letters, to the left. The bird was released at about midday and has not been seen since, despite much searching. I contacted Steve Hampton, a gull expert in California, and sent him a picture. He readily accepted the gull as showing characters of Glaucous-winged, and explained that the species is extremely variable. It is a matter of debate in America whether this is naturally occurring, or is a result of hybridisation over a great many years. I then sent him a close up picture of the wing tip. He commented that this was on the dark side for Glaucous-winged, and that there might be a trace of American Herring Gull in the ancestry. I also contacted John Martin in Bristol. He sent my picture to a colleague in America, Steve Howell. He said that he would accept the gull as Glaucous-winged , although the belly was a bit dark for a third-winter bird. We are now at the point of submitting this record to the BB rarities committee. It will be interesting to learn what they and the BOU decide. Will they accept it as a pure species, or will they find a trace of hybridisation in our photographs? No doubt there will be much debate, and it will be several months before we are told the outcome.
STOP PRESS: An email was received from Jon King in America today (3rd). His speciality is hybridisation amongst the large gulls. He confirms that this gull is a pure Glaucous-winged Gull, with no doubts.