Small leaf warbler found throughout the Philippines and Malaysia, as well Sumatra, Java, and Nusa Tenggara. Varies throughout range: Malaysian and Indonesian birds yellowish overall (particularly on the underparts) with a strongly contrasting head pattern and no wing bar, while birds in the Philippines are brownish above, lack a crown stripe, and often have a faint wing bar. Compare with migratory leaf warblers. As name suggests, a denizen of montane and hilly forests. Forages actively in upper levels of forest, often in mixed flocks. Song is a rolling series of high-pitched warbling notes.