THE BIRDS OF SOUTH GLOUCESTERSHIRE
CASPIAN GULL – Larus cachinnans
As with all reports of rare and scarce birds they are subject to ratification by the respective rarities committees
The taxonomy of the Herring Gull/ Lesser Black-backed Gull complex is very complicated, different authorities recognising between two and eight species. This group has a ring distribution around the northern hemisphere. Differences between adjacent forms in this ring are fairly small but by the time the circle is completed the end members, Herring Gull and Lesser Black-backed Gull are clearly different species. Caspian Gull is a name applied to the gull taxon Larus cachinnans. This form has a troubled taxonomic history and is currently treated as a full species by some authorities and a form of Herring Gull by others. In Britain at this time they are treated as a form.
There have been four Caspian Gulls reported from S. Gloucestershire, they are;
2002: (1)
An adult was seen on November 16th at Harnhill Land Fill near Elberton; An adult was seen at the same site on December 6th and was assumed to be the bird reported in November. This occurrence constitutes the first record of this form in S. Gloucestershire.
2003: (1)
An adult was located in the morning on November 19th at New Passage, it was pushed off by the rising tide and flew off south at 11:15. The same or another adult/ near adult bird was reported in fields just north of Northwick Warth tip at 13:40.
2004: (1)
On January 3rd an adult was found at Northwick Land Fill.
2007: (1)
A winter adult was seen at Shortwood Quarry Landfill site near Emerson's Green on December 14th.
Caspian Gull at Shortwood Landfill. December 2007: © Peter Rock.