The BOURC maintains the official list of birds recorded in Britain - the British List.

Each species on the List is assigned to a species category. Only those species in Categories A, B and C form the British List.

The British List uses the revised taxonomic treatment and sequence for grebes and passerines and other changes to the List adopted in the BOURC's 38th report.

Categories A, B & C
Category D
Category E
Category F (to follow)

The last published version of The British List is -
The British List: a checklist of the birds of Britain (7th Edition) (July 2006)
Recommended citation: British Ornithologists’ Union. 2006. The British List: A Checklist of Birds of Britain (7th edition). Ibis 148: 526-563.

The BOU and bird names
English and scientific names – 1923 to 2010 (Excel file)