White-shouldered Antshrike

Overview

The white-shouldered antshrike (Thamnophilus aethiops) is a species of bird in the family Thamnophilidae, commonly known as typical antbirds. It inhabits evergreen forests across a wide range in South America, including Bolivia, Brazil, Colombia, Ecuador, Peru, and Venezuela. The species is currently assessed as Least Concern by the IUCN, although its population size is believed to be decreasing.

Identification

• Size: 15 to 17 cm long, weighing 23 to 30 g.
• Plumage: Exhibits significant sexual dimorphism; adult males of the nominate subspecies are mostly black with white spots on the wing coverts and white underwing coverts, while adult females are entirely deep reddish brown.
• Bill: Stout with a hook, resembling those of true shrikes.
• Song: Males deliver a short, slowly paced series of low-pitched, complaining notes written as "anh...anh...anh" at about one note per second, often likened to a barred forest falcon or trogon.

Habitat

This species primarily inhabits the heavily vegetated understorey of evergreen forests. In the Andean foothills of Colombia, Ecuador, and Peru, it is found in lower elevation terra firme, while in Venezuela and Amazonian Brazil, it favours forest edges along watercourses and overgrown gaps. Elevation ranges vary by location, reaching up to 1,500 m in Peru.

Diet

The diet consists mainly of insects and other arthropods, though specific details are not fully known. The bird forages singly or in pairs within dense vegetation, usually between 1 and 5 m above the ground, though it has been recorded feeding as high as 8 m in bamboo stands. It gleans prey from leaves, stems, vines, and branches, occasionally foraging on the ground or following army ant swarms.

Did you know?

Although the white-shouldered antshrike is generally a shy feeder that rarely joins mixed-species flocks, it has been recorded following an army ant swarm through the understorey in a single observation in Brazil. The nominate subspecies is an exception to the solitary norm, joining mixed-species flocks more frequently in Ecuador and Peru than other subspecies.