Phylloscopus borealoides
The Sakhalin Leaf Warbler (*Phylloscopus borealoides*) is a small, energetic songbird, a cryptic member of the Old World leaf warbler family (Phylloscopidae). Measuring 11-12.5 cm (4.3-4.9 in) in length and weighing 8-10 grams, it exhibits typical leaf warbler plumage: dull olive-greenish upperparts, whitish to buffish underparts, and a prominent yellowish supercilium. Distinctive field marks include a generally pale median crown stripe (though often faint), two yellowish wing bars (the upper...
Breeds in deciduous or mixed coniferous-deciduous forests, often in montane areas with dense undergrowth or near streams. Winters in various forest types, including mangroves and secondary growth, from lowlands to moderate elevations.
Primarily insectivorous, feeding on small insects and their larvae (e.g., caterpillars, beetles, flies, aphids) and spiders, gleaned from foliage and branches.
Sakhalin Leaf Warblers are active, constantly moving insectivores, typically observed gleaning insects from foliage and branches, often in the mid-story and subcanopy, occasionally hover-gleaning or making short sallies. During the breeding season, males establish territories through vigorous son...
The Sakhalin Leaf Warbler breeds primarily on Sakhalin Island and the southern Kuril Islands (e.g., Kunashir, Iturup) of the Russian Far East, extending south to Hokkaido, Japan. During autumn and spring migration, individuals pass through Japan, the Korean Peninsula, and eastern China, utilizing...
Least Concern
- The Sakhalin Leaf Warbler was only recognized as a distinct species from the Arctic Warbler (*Phylloscopus borealis*) in the early 21st century, primarily due to differences in its unique song. - Its name is derived from Sakhalin Island, one of its primary breeding grounds in the Russian Far Ea...