Pallas's Leaf Warbler

Pallas's leaf warbler is one of the smallest Palearctic warblers, 9–10 centimetres long and 4–7 grams, with a relatively large head and short tail; it is slightly smaller than a yellow-browed warbler and barely larger than a goldcrest. It is greenish above and white below but very striking, with prominent pale yellow double wingbars, bold yellow supercilia and central crown stripe, and a lemon-yellow rump. (Wikipedia, general species account)

The species breeds in mountain forests from the Altai Mountains and southern Siberia east to the Sea of Okhotsk, northern Mongolia and northeast China. Its habitat is coniferous taiga of fir, spruce, pine and larch, or mixed forest with willow and alder and a high proportion of conifers, from sea level up to about 1,500–1,700 metres in Russia. It is strongly migratory, wintering mainly in subtropical south China, northern Thailand and northeastern Indochina, and is found in increasing numbers in Europe in autumn. (Wikipedia, general species account)