Pallas's Leaf Warbler

The Pallas's leaf warbler, Phylloscopus proregulus, is a diminutive and sprightly bird, one of the smallest of the Palearctic warblers. It is easily recognized by its vibrant plumage, with greenish upperparts and immaculate white underparts. A striking lemon-yellow rump and dual wingbars, along with yellow supercilia and a central crown stripe, make this bird a visual delight.

Identification Tips

When observing Pallas's leaf warbler, look for its relatively large head and short tail, which give it a distinctive silhouette. The yellow rump, although conspicuous at close range, can be elusive in dense foliage. The bird's bill is a subtle blackish-brown with a hint of yellow, and its legs bear a brownish hue with a green or greyish tinge.

Habitat

During the breeding season, Pallas's leaf warbler favors the coniferous taiga forests, rich with fir, spruce, pine, and larch, or mixed forests with a significant coniferous presence. In winter, it adapts to a broader range of habitats, including broadleaf forests and scrublands.

Distribution

This warbler breeds across Siberia, extending from the Altai Mountains to the Sea of Okhotsk, and into northern Mongolia and northeast China. It is a strong migrant, wintering mainly in subtropical south China and parts of Indochina. Increasingly, it is also found in Europe during autumn migrations.

Behaviour

The Pallas's leaf warbler is an active forager, often seen hovering like a goldcrest, albeit more frequently. It is not particularly shy, but its preference for the upper canopy can make it a challenge to spot.

Song & Calls

The song is a melodious and varied mix of whistles and trills, reminiscent of a canary, and can be heard from a concealed perch. The call is a soft, brief "dju-ee," distinct from the more complex songs of its former subspecies.

Breeding

The female constructs a cup nest in a tree or bush, where she lays 4 to 6 blue-grey flecked white eggs. Incubation is solely her duty, and the chicks, once hatched, are primarily fed by her, with both parents contributing post-fledging.

Similar Species

Pallas's leaf warbler can be confused with other yellow-rumped Asiatic warblers, but its brighter plumage and unique vocalizations help distinguish it. The buff-barred and Brooks's leaf warblers are larger and less vividly marked, while the ashy-throated warbler has greyer head markings.

Diet and Feeding

Insectivorous by nature, this warbler consumes a diet of small insects, including flies, moths, and aphids, as well as spiders. It forages in trees and bushes, adeptly picking food from leaves or capturing prey mid-flight.

Conservation Status

The Pallas's leaf warbler is classified as "Least Concern" by the IUCN. It has a vast range and is considered stable in population, being widespread, common, and locally abundant in its breeding territories.