Radde's Warbler

The Radde's warbler, a leaf warbler of the genus Phylloscopus, is a small bird comparable in stature to the willow warbler. It boasts an unstreaked brown back and buff underparts, with a strikingly long and prominent whitish supercilium. The bill, pointed and robust, is thicker than that of its relative, the dusky warbler. Notably, the legs are of a lighter shade, and the feet appear somewhat oversized, a reflection of the bird's terrestrial inclinations. Both sexes of Radde's warbler present a similar plumage, which is typical among warblers. Juveniles, however, tend to exhibit a more yellowish hue on the underparts.

Identification Tips

When identifying Radde's warbler, look for the very long and conspicuous whitish supercilium and the thicker bill in comparison to the dusky warbler. The bird's legs are paler, and the feet are relatively large. The call of Radde's warbler is a soft "chick" sound, which can be a helpful identifier.

Habitat

During the breeding season, Radde's warbler can be found in open deciduous woodlands with a fair amount of undergrowth and bushy woodland margins, often in proximity to water sources. In its wintering grounds, it prefers the edges of forests, dense scrub, and bushy areas near woodlands.

Distribution

Radde's warbler breeds in the southern regions of Central and Eastern Siberia, extending as far east as Korea and Manchuria. It is a migratory bird that winters in Southeast Asia, including Bangladesh, Cambodia, Laos, Myanmar, and Thailand.

Behaviour

This warbler is a strong migrant, traveling vast distances between its breeding and wintering territories. It is also known for occasional vagrancy to western Europe, despite being typically found 3000 km away from its breeding grounds. Notable records include sightings at the Copeland Bird Observatory in County Down, Northern Ireland, and as an accidental visitor in Heligoland.

Breeding

The nest of Radde's warbler is constructed low within a bush, where approximately five eggs are laid. These eggs have a greyish background color, densely mottled and streaked with fine brownish-olive markings that nearly obscure the base color. The eggs measure around 17 by 13 millimeters.

Similar Species

Radde's warbler can be confused with the dusky warbler, but it can be distinguished by its thicker bill, paler legs, and larger feet. Additionally, the supercilium of Radde's warbler is more pronounced.

Diet and Feeding

As an insectivorous bird, Radde's warbler feeds on a variety of insects, which it typically forages for in its woodland habitat.

Conservation status

The Radde's warbler is currently listed as Least Concern on the IUCN Red List, indicating that it is not at immediate risk of population decline or habitat loss at a global scale.