The first occurrence of this North American species in Britain was at Skomer on 5 October 1961 (D.R. and S.M. Saunders). The record was submitted to BBRC which concluded it was “probably” this species. At that time many people were doubtful that small birds could cross the Atlantic unaided. There the matter lay until 1988 when the record was re-submitted, it having been established by then that passerines from North America regularly occur in the British Isles. Both BBRC and BOURC accepted it and the species was admitted to the British list in 1990 (Saunders and Saunders 1992).
SAUNDERS, D.R., and SAUNDERS, S. 1992. Blackburnian Warbler, new bird for Britain. British Birds 85: 337