Pallas's Warbler
Scientific classification
Kingdom: Animalia
Class: Aves
Family: Sylviidae
Genus: Phylloscopus
Binomial name
Phylloscopus proregulus

The Pallas's Warbler, or Pallas's Leaf Warbler, Phylloscopus proregulus , is a leaf warbler which breeds in southern Siberia, Mongolia and parts of Tibet and China.

This is a bird of coniferous mountain woodlands. The nest is built in a tree. Like most Old World warblers, this small passerine is insectivorous.

It has recently been split into three species. The northern \'Pallas's Warbler', P. proregulus is strongly migratory and winters in subtropical Asia.

This tiny warbler is prone to vagrancy as far as western Europe in late October and November, despite a 3000km distance from its breeding grounds. For example, this species occurs in late autumn in Great Britain regularly enough that it is not classified as rare there.

This is one of the smallest warblers, and shares greenish upperparts and off-white underparts with typical leaf warblers. However, this is a little jewel of a bird, with prominent double wing bars, supercilia and crown stripe, and a lemon-yellow rump.

This bird is not shy, although its arboreal life style makes it difficult to observe. It is constantly in motion, and often hovers briefly, like a kinglet. Its song is powerful and Canary-like.

The closely related southern species, Lemon-rumped Warbler, P. chloronotus, and Gansu Leaf Warbler, P. kansuensis, move to lower latitudes in winter, but do not migrate long distances.

This bird is named after the German zoologist Peter Simon Pallas.