Despite being an Asian breeding species this is not an unfamiliar species in Dorset during autumn and winter.
The yellow-browed warbler (Phylloscopus inornatus) is probably the most common of Dorset's rare birds! It is a species that breeds in eastern Russia, China and other parts of Asia and normally overwinters in India and other parts of southern Asia and so this is not a species you would expect to find in Dorset yet, nevertheless, every autumn a small number turn up here; it is expected not hoped for! The RSPB estimate about 300 birds reach Britain each autumn although some years can see something of an irruption with far more arriving. Of those 300 birds most are seen on the east coast but probably 10 or so are reported in Dorset each winter.
The first autumn arrivals are reported from week 38 onwards with the number of records increasing each week through to a peak in week 43 after which there are then just a trickle of reports through until week 7 at the end of February. There are reports for every week from week 38 until week 7 so whilst the October peak reflects a definite passage through the county it seems one or two will stay the winter. There would not appear to be any evidence of a return spring migration through Dorset, if these autumn birds are returning to their northern breeding grounds in spring they must do it by an alternative route.
The distribution map shows that most records are from coastal locations with the Poole area and the Fleet featuring and the Observatory on Portland see and ring several. This coastal distribution may be distorted by these sites being the most watched and there may be unrecorded birds elsewhere in the county as, unlike waders and ducks for example, they do not appear to have a preference for coastal habitat.
It should be possible to add yellow-browed warbler to your Dorset list if you watch the birding news reports and react quickly when a bird is being seen somewhere regularly.