Mourning Warbler

The Mourning Warbler, Geothlypis philadelphia, is a diminutive and vibrant member of the New World warbler family. This species is adorned with yellow underparts and olive-green upperparts, a distinctive combination in the avian world. The male is particularly noted for its gray hood, which has been likened to a mourning veil, giving rise to the bird's evocative name.

Identification Tips

When observing the Mourning Warbler, look for its yellow underparts and olive-green upperparts, complemented by a thin, pointed bill and pink legs. Adult males boast a gray hood with black lores and a black patch on the throat and breast. Females and immature birds present a gray-brown head with an incomplete eye-ring and a yellow-gray throat. The species measures between 10–15 cm in length, weighs 11-13 g, and has a wingspan of approximately 18 cm.

Habitat

The Mourning Warbler selects dense second-growth forests as its preferred habitat, with a particular fondness for areas with a thick understory and a covered canopy. During the winter months, these birds gravitate towards wet lowland habitats with dense vegetation.

Distribution

Breeding grounds for the Mourning Warbler are found in southern Canada, while migration can bring sightings across the central and eastern United States, as well as in Belize, Bonaire, Puerto Rico, Guatemala, Panama, and other Central American locales. The species migrates to Central America and northern South America for the winter season.

Behaviour

This warbler is known to forage low in the vegetation, occasionally sallying forth to catch insects in mid-flight. It exhibits a unique behavior when threatened, with both adult males and females feigning injury to distract predators from their nests.

Song & Calls

The Mourning Warbler's song is a bright, rolling warble that often diminishes in volume towards the end, reminiscent of the phrase "chirry, chirry, chirry, chorry, chorry." Its call is a sharp chip, with variations in pitch, including a higher note that contrasts with the harsher chip.

Breeding

In the breeding season, Mourning Warblers can be found in southern Canada, nesting in thickets and semi-open areas with dense shrubs. Their nests are open cups, artfully concealed on the ground under thick vegetation, and constructed from grass, leaves, and bark, with a lining of roots or similar materials. Clutches typically consist of 2-5 eggs, which are white or speckled with brown and black.

Similar Species

The Mourning Warbler can be confused with the MacGillivray's Warbler, especially in females and immature birds, but their ranges do not overlap in the west. Other similar species include the Connecticut Warbler, which has a complete eye ring, and the Nashville Warbler, which has a yellow throat and is smaller in size.

Diet and Feeding

The diet of the Mourning Warbler is primarily insectivorous, including insect larvae and spiders picked from shrub branches. They also consume some plant material, such as fruiting bodies from the Cecropia tree during the winter. Notably, they are known to remove the legs and wings of insects before consumption.

Conservation Status

Despite a decline of about 43% in the last 50 years, the Mourning Warbler is currently classified as a species of Least Concern. With an estimated global breeding population of 17 million, the species appears to be adapting well to human-altered landscapes that provide the disturbed forest habitats it prefers.