[order] Passeriformes | [family] Sylviidae | [latin] Phylloscopus proregulus | [UK] Pallas Leaf-Warbler | [FR] Pouillot de Pallas | [DE] Goldhähnchen-Laubsänger | [ES] Mosquitero de Pallas | [IT] Luì del Pallas | [NL] Pallas Boszanger

Pallas Boszanger determination

copyright: B. Clibbon

This bird looks like a warbler but is scarcely bigger than a Goldcrest and has a dazzling array of yellow stripes in its plumage - two in each wing and no less than three through its head. On top of all that it keeps hovering in front of you like a humming bird, showing off a neat, square yellow rump. The only species which comes close to matching this suite of pale markings is the Yellow-browed Warbler but this isn't so dainty and lacks both the yellow rump and the pale central crown stripe.

Breeds in middle and lower middle latitudes of east Palearctic, in taiga towards north of range at high altitudes optimally at 2000-3000 m in western Himalayas, up to 4000 m in C and E Nepal and further east. Frequents uneven-aged taiga-type forest rich in thick undergrowth ascending to upper limits, stunted conifers, and open woodlands with shrubby meadows, but sings from tops of tall trees where available, and nests in pines 3-4 m above ground.

A rare vagrant to the West Palearctic from Siberia. The breeding range includes much of eastern Asia, north of the Himalayas and the normal wintering area is in south east Asia including India and Indochina.

Insects and a few other invertebrates. Highly active when foraging, impression being enhanced by constant fluttering and wing-flicking which perhaps serve to disturb prey. Picks or snatches items from twigs and leaves of trees and bushes, sometimes after short flight. Often pursues insects in agile flight, during and twisting.

This species has an Extent of Occurrence that has not yet been quantified, but it is not believed to approach the thresholds for the range criterion of the IUCN Red List (i.e. Extent of Occurrence less than 20,000 km2 in conjunction with both severe fragmentation and fluctuation/declines). The global population size has not been quantified, but it is believed to be large as the species is described as 'common' in at least parts of its range (Baker 1997). Global population trends have not been quantified, but the species is not believed to approach the thresholds for the population decline criterion of the IUCN Red List (i.e. declining more than 30% in ten years or three generations). For these reasons, the species is evaluated as Least Concern. [conservation status from birdlife.org]

Breeds Jun-July in USSR. Nest site is on ground, in or against tussock, mound, windfall debris, or among tree roots. Nest is a domed structure with side entrance, of dry grasses, moss, rotten wood, plant fibre, and rootlets, lined with finer material. 4-7 eggs are laid, incubation 11-14 days, by female.

Northern populations are long-distance migrants, southern populations make shorter, mainly altitudinal movements. Main movements are through eastern Asia. Regular autumn vagrant to north-west Europe; increasingly frequent since 1960s, previously rare. Occurrences involve mostly 1st-years and probably result chiefly from westward displacement in anticyclonic conditions, with reverse migration as possible additional factor. A few birds may occasionally overwinter.