Tickell's Leaf Warbler

Tickell's Leaf Warbler (Phylloscopus affinis) is a small active Asian leaf warbler with yellowish underparts and eyebrow, olive upperparts and no strong wing bar. Body shape, bill structure, plumage pattern and voice provide the strongest field characters. Age, sex and season may alter its appearance, so identification should combine several features and careful direct field comparisons with similar species in the same habitat (Wikipedia, general species account).

It moves rapidly through canopy and low shrubs, gleaning insects and making short aerial sallies beneath leaves and twigs; its clear yellow underside helps separate it from similar species. Its movements and social behaviour vary through the year, with breeding birds generally more dispersed and non-breeding birds gathering where food is concentrated. The Korean vertebrate catalogue used for this guide records the species in South Korea (Wikipedia, general species account; Wildlife of Korea occurrence records).