The Setophaga pensylvanica, commonly known as the Chestnut-sided Warbler, is a small songbird native to North American deciduous forests. It is known for its striking plumage, featuring a bright yellow crown, white belly, and distinctive chestnut sides. This species thrives in early successional habitats and is known for its energetic and acrobatic foraging behaviors.

Setophaga pensylvanica, commonly known as the Chestnut-sided Warbler, is native to North America. Its geographical distribution includes parts of Canada and the United States, primarily in the northeastern and central regions. The breeding range extends from southern Canada (including provinces such as Ontario, Quebec, and the Maritime Provinces) down to the northeastern United States, reaching as far south as the Appalachian Mountains.

The Chestnut-sided Warbler typically inhabits deciduous and mixed woodlands, with a preference for young, regenerating forests and shrublands. These environments are often characterized by dense undergrowth and secondary growth following disturbances like logging or natural disasters. The species thrives in areas with a high density of shrubs and small trees, which provide ample cover and feeding opportunities.

In its ecological niche, the Chestnut-sided Warbler primarily feeds on insects and other small invertebrates, which it gleans from foliage and branches. It is an active forager, often seen flitting through the dense vegetation in search of prey. The species plays a role in controlling insect populations and contributes to the biodiversity of its habitat. During the non-breeding season, the warbler migrates to Central America and the Caribbean, where it occupies similar habitats with dense vegetation.