The bird was reported to be a Siberian Chiffchaff, but this has since been disputed by birding experts.
The bird did seem to have slightly different colourations than a UK Chiffchaff - having a greyer back. Also notable were the warm buff markings below the eye and blacker legs and beak.
That said, some UK Chiffchaffs over-winter in the south of the UK and the presence of some yellow on the bird's breast made it unlikely it was a Siberian Chiffchaff. To meet BBRC tristis criteria a Chiffchaff needs to have an absence of yellow away from the underwing. This bird appears to have yellow tints on its underparts so does not meet these criteria.
