Its song is a high-pitched medley of whistles; the call is piercing, often disyllabic "tseeweest", strikingly loud for the bird's small size.

The only real possibility of confusion is with the similar-looking Hume's leaf warbler (P. humei), which in the limited area of overlap has duller colours, a faint second wing bar and dark legs and lower mandible.

It can easily be distinguished from Pallas's warbler as it does not have the conspicuous yellow central crown stripe and rump patch shown by that species.

Its winter habitat is lowland broadleaf or coniferous forest, from West Bengal and Assam in northeastern India east through southern China to Taiwan, and through Bangladesh south to the Malay Peninsula.

In summer, it occurs at altitudes of up to 2,440 m, and in winter, up to 1,525 m.[2] The European breeding population west of the Urals has increased westwards in recent decades; in 1950 it was described as 'fairly scarce', but 'locally abundant' with 45,000–46,000 pairs in 1990.

Exact numbers in this population are unknown, but typically several hundred are found arriving in Great Britain each autumn; given their unobtrusive behaviour, this is probably only a fraction of the total.