Cerulean Warbler

The Cerulean Warbler (Setophaga cerulea) is a diminutive member of the Parulidae family, a group known for their vibrant plumage and melodious songs. This species exhibits a striking sexual dichromatism; the males are adorned with a cerulean blue back and a stark black necklace, while females and immature birds display bluish-green upperparts and a more subdued yellow below.

Identification Tips

To identify the Cerulean Warbler, look for the following characteristics:

• Adult males: Cerulean blue and white upperparts, black necklace, and streaks on the back and flanks.
• Females and immatures: Bluish-green upperparts, pale eye stripe, and yellow below.
• Both sexes: Two white wing bars and a thin, pointed bill.

Habitat

During the breeding season, Cerulean Warblers favor large, mature deciduous hardwood forests, often nesting and foraging high in the canopy. They show a preference for riparian areas and require extensive forested landscapes to support their populations.

Distribution

The Cerulean Warbler breeds in eastern North America, with a range extending from southern Tennessee to southern Ontario. It winters on the eastern slopes of the Andes in South America, where subtropical forests provide suitable habitat.

Behaviour

Cerulean Warblers are insectivorous and forage predominantly on insect larvae. They exhibit strong territorial behavior, with males arriving earlier than females to establish breeding grounds. The species is monogamous, and both sexes are involved in nest construction, which takes place high in the forest canopy.

Song & Calls

The male's song is a distinctive buzzed "zray zray zray zray zeeee," while the primary call is a buzzy, metallic "zzee." Females rarely sing but may call when nesting, and an alarm call signals the presence of predators.

Breeding

Breeding occurs from late May to early June, with nest construction taking about a week. Females lay 3 to 5 eggs, which are incubated for approximately 12 days. Nestlings fledge after about 11 days, with both parents providing food.

Similar Species

The Cerulean Warbler can be confused with other blue-hued warblers, but its unique coloration, habitat preference, and song distinguish it from its relatives.

Diet and Feeding

The diet consists mainly of lepidopteran larvae and winged insects. Foraging occurs in the mid to upper canopy, with males typically foraging at higher elevations than females.

Conservation Status

The Cerulean Warbler is classified as Near Threatened due to rapid population declines, primarily caused by habitat loss in both breeding and wintering ranges. Conservation efforts are underway to protect critical habitats and slow the species' decline.