The body size index and body condition were calculated separately for each sex because the glaucous gull
is sexually dimorphic (Gilchrist 2001; Davenskiold 1964).
Our trip started at Anderton Marina, near Northwich, where we took possession of Glaucous Gull
, a modern 66ft craft.
Juvenile glaucous gull
at Foryd Bay (pic by Robin Sandham)
A first-winter Iceland gull was found behind the recycling centre near Abergele on Saturday, another was at RSPB Point of Ayr and two at Pontllyfni on Sunday, where a glaucous gull
was also found.
Golden Oriole, Blue-headed Wagtail, Pied Flycatcher, Firecrest and Glaucous Gull
and Iceland Gull have also been on the island this week, though rarer than all of these for the island was a House Sparrow
An immature Glaucous Gull
, another Arctic-edge species, was at Red Wharf Bay on Saturday, perhaps the same one that was in Holyhead Bay on Sunday, where a Black-necked Grebe fished off the quay.
We observed the depredation of a King Eider chick from a tracked brood by a Glaucous Gull
(Larus hyperboreus) and witnessed two unsuccessful attacks on radio-tracked broods, including one by two Parasitic Jaegers (Stercorarius parasiticus) and another by a Glaucous Gull
The large numbers of gulls from the Arctic remained into last week, including an ivory-white Glaucous Gull
patrolling the coast between Aberdesach and Dinas Dinlle.
Many winter birds remain, including Bonaparte's gull and glaucous gull
on Anglesey, and great grey shrikes at World's End and Alwen Reservoir.
A Glaucous Gull
in Beddmanarch Bay was new this week, otherwise most sightings were long-stayers: Long-tailed Ducks on Llyniau Penrhyn and Trawsfynydd, with 14 off Black Rock Sands, where a Surf Scoter remains.
The Bonaparte's gull remains at Lligwy Bay for its fourth week, while Menai Straits' glaucous gull
has been in Bangor harbour and west of Menai Bridge.
An Iceland Gull was at Penrhos Coastal Park and a Glaucous Gull
was blown past Bardsey.