This is a typical leaf-warbler in appearance, grayish-green above and off-white below. The single wing bar found in the southern and western populations distinguishes them from most similar species (except Arctic WarblerP. borealis). It is slightly smaller than that species and has a thinner bill, without a dark tip to the lowermandible. A latitude-based analysis of wintering birds indicated that more northerly P. trochiloides are smaller, i.e. this species does not seem to follow Bergmann's rule
Its song is a high jerky trill, in some populations containing a sequence of down- and more rarely up slurrednotes.
It breeds in lowland deciduous or mixed forest; non-breeding birds in the warmer parts of its range may move tomontane habitat in summer. Individuals from southeast of the Himalayas are for example quite often seen inBhutan during the hot months, typically in humid Bhutan Fir (Abies densa) forest up to about 3,800 meters ASLor more, but they do not breed there and return again to the adjacent subtropical lowlands in winter