The Cerulean Warbler, Dendroica cerulea, is a small songbird of the New World warbler family.
Adult males have pale cerulean blue upperparts and white underpants with a black necklace across the breast; they also have black streaks on the back and flanks. Females and immature birds have greyer or greenish upperparts, a pale stripe over the eye, and no streaking on the back and no necklace. All of theses birds, regardless of their age, have wing bars and a thin pointed bill.
Their breeding habitats are mature deciduous forests in eastern North America. Their nests are cup-shaped, and are placed on a horizontal branch high in a hardwood tree.
These birds migrate to forested mountain areas in South America.
They forage actively high in trees, sometimes catching insects in flight. These birds mainly eat insects.
The song of this bird is a buzzed zray zray zray zray zeeee. The call is a slurred chip.
In fragmented forest areas, this bird is vulnerable to nest parasitism by the Brown-headed Cowbird. This bird's numbers are declining faster than any other warbler species in the USA; its population nowadays is less than one-fifth of what it was 40 years ago .