Black-throated Blue Warbler, Setophaga caerulescens

Black-throated Blue Warbler, Setaphaga caerulescens. Photograph taken within a residential community in Hereford, Arizona, October 2010. Photograph and identification courtesy of Bob Behrstock, Sierra Vista, Arizona (naturewideimages.com).

Background and Identification

The Black-throated Blue Warbler, Setaphaga caerulescens, is a member of the Parulidae Family of New World Warblers, which has one hundred eleven individual species that have been placed into eighteen genera, and one of thirty-four global members of the Setophaga Genus. They prefer the dense growth of interior forests but are spotted in urban areas where food is abundant. This species is one of the most intensely studied migratory passerine species in North America, and the many research studies done on these warblers have led to many ornithological advancements. Some of these advancements are focused on the factors and processes that limit and/or regulate populations and where they operate. These include urban developments, farms, factories, tree distribution, and food density. In Mexico, the Black-throated Blue Warbler is known as Reinita Azulada.

This species exhibits sexual dimorphism, males are more brightly colored than females and juvenile individuals. Adult males are easily identifiable by their deep blue upperparts, black face and throat, and white underparts. They also have a distinctive white wing patch, often referred to as a “pocket handkerchief.” Females are more subtly colored, with olive-brown upperparts, yellowish underparts, and a faint white eyebrow stripe. Despite their differences, both sexes share the same overall body shape and size, with a length of about 13 cm (5.1 inches) and a weight of about 9 g (0.32 oz). Their song is a musical “zur-zur-zree,” which is often heard during the breeding season.

Habitat and Geographical Range

The Black-throated Blue Warbler prefers deciduous and mixed forests, particularly those with dense understory vegetation. They are often found in mature forests with a well-developed shrub layer, which provides ample cover and foraging opportunities. While in warmer climates (during the winter), they favor forested habitats and can often be found in dense tropical and subtropical forests, as well as in shade coffee plantations and other areas with rich vegetation.

This species migrates over long distances throughout the year. During the breeding season, they are commonly found in the northeastern United States and southeastern Canada, including the Appalachian Mountains. In the winter, these warblers migrate to the Caribbean, Central America, and the northern parts of South America.

Common Misidentifications

The Black-throated Blue Warbler can be confused with other small, blue songbirds, such as the Cerulean Warbler, Setophaga cerulea, and the Northern Parula, Setophaga americana. The Cerulean Warbler is lighter blue overall and lacks the distinctive black throat and face of the male Black-throated Blue Warbler. The Northern Parula, on the other hand, has a more complex coloration with a blue-gray back, yellow throat, and white eye arcs.

Conservation Status

From a conservation perspective the Black-throated Blue Warbler is currently considered to be of Least Concern. Their population is considered stable, and they are widespread across both their breeding and wintering ranges.