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A small (4 ½ inches) wood warbler, the male Cerulean Warbler is most easily identified by its pale blue head and back, white chin with dark throat stripe, and white breast. Female Cerulean Warblers are pale green overall with a faint white eye-stripes. The male Cerulean Warbler may be distinguished from the related Black-throated Blue Warbler (Setophaga caerulescens) by that species’ darker blue coloration and black throat, whereas the female Cerulean Warbler may be distinguished from the female Black-throated Blue Warbler by that species’ browner body and darker breast. The Cerulean Warbler breeds locally in southern Canada and portions of the eastern United States from Minnesota south to Arkansas and from Massachusetts west to Kansas. Within that range, this species is mostly or completely absent from the southeastern coastal plain and portions of the upper Midwest. In winter, Cerulean Warblers may be found in northern South America, primarily from Columbia south to Bolivia. Cerulean Warblers breed in deciduous forest habitats, preferring dense forest to more open woodland. In winter and on migration, this species is primarily found in humid tropical forests. Cerulean Warblers primarily eat small invertebrates, including insects and spiders, but this species may also eat small quantities of plant material in winter. In appropriate habitat, Cerulean Warblers may be observed foraging for insects on leaves, twigs, and branches in the tree canopy. Birdwatchers may also listen for this species’ song, a series of buzzing notes rising in pitch at the end. Cerulean Warblers are primarily active during the day, but, like many migratory songbirds, this species migrates at night.