Bolivian Tyrannulet

Overview

The Bolivian tyrannulet (Zimmerius bolivianus) is a monotypic species of bird in the family Tyrannidae, the tyrant flycatchers. It is a year-round resident classified by the IUCN as Least Concern, despite a believed decreasing population size.

Identification

• Measures 10 to 12 cm in length with a weight of 10 to 11.6 g, featuring a dark olive crown, face, and upperparts.
• Wings are mostly dark dusky with coverts and flight feathers having thin bright yellow-green edges, while the belly and undertail coverts are pale yellow.
• Possesses a small rounded black bill that may have a deep reddish, purple, or gray mandible, along with black legs and feet.
• Dawn song consists of a rising, plaintive series of whistles described as 'hee-hee-heEEew', with a call that is a mellow descending 'teew'.

Habitat

Found on the east slope of the Andes, ranging from south-central Peru southeast into Bolivia's Cochabamba Department. It inhabits humid montane forest and cloudforest, clearings within the forest, and nearby secondary forest at elevations between 1,000 and 2,830 m.

Diet

Feeds on insects and small fruits, particularly those of mistletoes. Forages singly or in pairs, sometimes joining mixed-species feeding flocks, and mostly operates in the forest canopy by actively moving about and gleaning food while perched or briefly hovering.

Did you know?

Nothing is known about the breeding biology of the Bolivian tyrannulet.