Radde's Warbler (Phylloscopus schwarzi), is a leaf warbler which breeds in Siberia. This warbler is strongly migratory and winters in southeast Asia.
This is a bird of open woodlands with some undergrowth near water. The nest is built low in a bush, and eggs are laid. Like most Old World warblers, this small passerine is insectivorous.
This small warbler is prone to vagrancy as far as western Europe in October, despite a 3000 km distance from its breeding grounds. It has been recorded from the Copeland Bird Observatory in County Down, Northern Ireland where it was first recorded for Northern Ireland in 2008.
This is a warbler similar in size to a Willow Warbler. The adult has an unstreaked brown back and buff underparts. There is a very long prominent whitish supercilium, and the pointed bill is thicker than that of the similar Dusky Warbler. The legs are paler than Dusky's, and the feet look large, reflecting the more terrestrial lifestyle of this warbler. The sexes are identical, as with most warblers, but young birds are yellower below. The call is a soft chick.
The binomial commemorates the German astronomer Ludwig Schwarz (1822-1894).