This small leaf warbler has a yellow eyebrow and two wing bars. It breeds in the Siberian taiga and spends most of the winter in Southeast Asia.
The upperparts are green and the underparts white or greyish white. Dark lines border the broad yellow eyebrow, and the wings have two yellow bars.
Yellow-browed Warblers breed in Siberia and normally spend winter in southern Asia. In recent decades, autumn records in Western Europe have increased, with many birds recorded from Scandinavia to the Iberian Peninsula. Researchers ask whether these birds are vagrants outside their usual route or the start of a new migration route.
The review compares European sightings and recoveries of ringed birds. Current evidence suggests that most Yellow-browed Warblers in Europe are still vagrants. At the same time, winter records from southern Europe and North Africa have increased, leaving open the possibility that a new route is developing. Spring records in Europe remained far below autumn records, at about 1–2% of autumn counts depending on the locality.
An extinction-risk assessment has not been added yet.
The review says a new route would need evidence that birds survive in Europe, return to their breeding grounds, reproduce, and pass the route to their offspring. European sighting totals also vary with observer effort and reporting bias, so ringing recoveries and breeding evidence are key clues.