The genus name Phylloscopus is from Ancient Greek phullon, "leaf", and skopos, "seeker" (from skopeo, "to watch").

The dusky warbler is prone to vagrancy as far as western Europe in October, despite a 3000 km distance from its breeding grounds.

The sexes are identical, as with most warblers, but young birds are more olive-tinged above.

Like most warblers, it is insectivorous, but will take other small food items, including berries.

The call is often the first clue that this typically skulking species is present, away from the breeding grounds.