The Chestnut-sided Warbler is a small bird of young deciduous woods and thickets. Its plumage changes between breeding and nonbreeding seasons.
Breeding adults have grey-and-white plumage, a yellow crown, dark face markings and chestnut flanks. Males are more richly marked than females, and the amount of chestnut varies. Outside breeding, adults and immatures are brighter lime-green above with a white eye-ring.
It eats caterpillars, fly larvae and other insects, moving among branches as it inspects the undersides of leaves.
An extinction-risk assessment has not been added yet.