A small, slim warbler with a long tail. Breeding males are distinctive, with gray upperparts contrasting with a puffy rufous throat and breast, and a bold white moustache mark. Female and non-breeding males resemble a washed-out version of the breeding male, with much less rufous below. Typically found in scrubby, dense bushy habitats, but also in more open woodland and savanna. Sings from the tops of bushes, giving a rattling and loud sequence of notes. The call is a dry "tek" note, which is also incorporated into the song. Very similar to Moltoni’s Warbler, and best separated by call (single notes rather than dry rattles); breeding male is also richer rufous below. Also very similar to Eastern Subalpine Warbler, but call is subtly different: Western’s is slightly harsher, with only one syllable. Breeding males are separated visually from Eastern by having more rufous on the belly, a paler face, and a narrower white moustache.