The MacGillivray's Warbler, Geothlypis tolmiei, is a small songbird known for its vibrant yellow underparts and olive-green upperparts. It inhabits dense thickets and shrubs in North America's western regions. This warbler is notable for its shy nature, skulking behavior, and distinctive black hood covering its head.

Geothlypis tolmiei, commonly known as MacGillivray's Warbler, is native to North America. Its geographical distribution includes the western regions of the continent, ranging from southern Alaska through much of Canada, and into the western United States. During migration, it can be found across various parts of the United States as it travels to its wintering grounds in Central America and the western regions of Mexico.

MacGillivray's Warbler typically inhabits dense shrubs and thickets, often in riparian areas, regenerating forests, or along forest edges. It prefers environments with ample cover and is frequently found in areas with a mix of deciduous and coniferous vegetation. The climate in its breeding range is generally temperate, with variations depending on altitude and latitude.

The species is primarily insectivorous, feeding on a variety of insects and small arthropods. It plays a role in controlling insect populations and contributes to the ecosystem as both a predator of small invertebrates and a prey species for larger predators. Its preference for dense understory vegetation makes it an important component of the ecological community in these habitats, contributing to the structural diversity of the habitat.