Alternative name: Pallas's Warbler
- Phylloscopus proregulus
Greenish upperparts and off-white underparts, prominent double light yellow wing bars, golden yellow supercilium, light yellow crown stripe, light yellow tertial tips, and (usually only visible in flight) a lemon-yellow rump. Frequently hovers while flycatching or picking insects off leaves, when the rump can be conspicuous.
It breeds in southern and eastern Siberia (Novosibirsk east to Vladivostock and Magadan), northern Mongolia, and northeastern China (Heilongjiang, northeast Inner Mongolia). It is strongly migratory, wintering mainly in subtropical southeast Asia, from the Yangtze River in China south to Laos and northern Vietnam.
Prone to vagrancy as far as western Europe from mid October to late November, the 5,000-6,000 km distance from its breeding grounds being little longer than that (3,500-4,500 km) to its normal wintering grounds. For example, it occurs in late autumn in Great Britain regularly enough (up to 300 per year) that it is not classified as rare there. This is now considered to be an evolving new migration route, with birds using the mild oceanic winters of western Europe as a new wintering area.
Pallas's Leaf Warbler and its close relatives from the Sino-himalayan highland region, Pale-rumped Warbler P. chloronotus, Chinese Leaf Warbler P. yunnanensis, and Gansu Leaf Warbler P. kansuensis, were until recently treated as a single species, being split first on vocal, ecological and biogeographical grounds, the splits later confirmed from genetic data. Both Pallas's Leaf Warbler and Pale-rumped Warbler have been named "Lemon-rumped Leaf Warbler" but by different authorities, though only for Pale-rumped Warbler in recent texts subsequent to the species complex being split.
Breeds in coniferous (fir Abies, larch Larix, pine Pinus, spruce Picea) forests or mixed forests with a high proportion of conifers, from sea level to 1,700 m altitude. On migration and in winter in more varied forest and scrub habitats.
The nest is built in a tree.
Diet mainly small insects and spiders.
- Clements, JF. 2011. The Clements Checklist of Birds of the World. 6th ed., with updates to August 2011. Ithaca: Cornell Univ. Press. ISBN 978-0801445019. Spreadsheet available at http://www.birds.cornell.edu/clementschecklist/downloadable-clements-checklist
- Del Hoyo, J, A Elliot, and D Christie, eds. 2006. Handbook of the Birds of the World. Volume 11: Old World Flycatchers to Old World Warblers. Barcelona: Lynx Edicions. ISBN 978-8496553064
- Gill, F and D Donsker (Eds). 2014. IOC World Bird Names (version 4.3). Available at http://www.worldbirdnames.org/.
- Gilroy, J. J., & Lees, A. C. (2003). Vagrancy theories: are autumn vagrants really reverse migrants? British Birds 96: 427-438.
- Birdforum post giving potential splits of the genus Phylloscopus.
- BirdForum Opus contributors. (2021) Pallas's Leaf Warbler. In: BirdForum, the forum for wild birds and birding. Retrieved 27 January 2021 from https://www.birdforum.net/wiki/Pallas%27s_Leaf_Warbler