The cerulean warbler (Setophaga cerulea) is a small songbird of the New World warbler family. Adult males have pale cerulean blue and white upperparts with a black necklace across the breast and 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 neck. All of these birds have wing bars and a thin pointed bill.