Yellow-browed Warbler, Ross Castle, 9th January 2016 (Davey Farrar).
This is the first winter record for Kerry of this tiny Siberian Warbler, though perhaps not as surprising is the location, the stream at Ross Castle, Killarney, where in recent years 50+ Chiffchaffs and at least 7 'Tristis' or Siberian Chiffchaffs have wintered. 3 Tristis and about 30 Chiffchaff are currently at the site, despite the floods in the area and the unusually mild winter so far.
Despite their small size, Yellow-broweds migrate huge distances, with birds from northern Siberia wintering on the NE Indian subcontinent, SE Asia and Taiwan, so this tiny bird is really on the 'wrong' side of the world. The nearest breeding grounds to us are around the Ural Mountains and Pechora River in Russia, a straight line distance of at least 3,500 km (2,200 miles).
Breeding range (yellow) and wintering areas (blue) of Yellow-browed Warbler. (from HBW Alive).