Description: Small Yungas tyrannulet approximately 11 cm long, with a compact and large-headed appearance. It has a gray crown contrasting with the olive-green upperparts, a thin and well-defined white supercilium, and a faint dark line at eye level. Whitish throat, grayish chest, and belly with whitish-yellow tones and somewhat yellowish flanks. The wings show two well-marked light wingbars ranging from cinnamon to beige. Relatively short and dark tail. Bill short, thin, and pointed, black or with a paler lower mandible; legs grayish. Sexes similar. Juveniles resemble adults although duller. It may occur together with the White-throated Tyrannulet (M. leucophrys), from the same genus, although the latter has a much more contrasting white throat and a more slender appearance. It may also be confused with the Rufous-rumped Tyrannulet (Tyranniscus uropygialis), an occasional species in Argentina with recent records in the Yungas of Jujuy, which shows a darker gray crown and a striking bright cinnamon rump.
Geographic distribution: Distributed along the Andes from southeastern Peru to northwestern Argentina. In Argentina, it inhabits the Yungas of Jujuy, Salta, and Tucumán, with scarce records in Catamarca, mainly between 1,000 and 2,800 m above sea level, although locally it may reach higher elevations. Its presence in the country appears to be concentrated mainly between spring and autumn, suggesting possible seasonal movements that remain poorly understood.
Habitat: Inhabits humid montane forests of the Yungas, especially associated with mountain alder forests (Alnus acuminata) and mountain podocarp forests (Podocarpus parlatorei). It is mainly observed in the middle and upper strata of the vegetation.
Diet: Primarily insectivorous, feeding on small invertebrates captured among foliage and branches.
Behavior: Generally solitary, although it often joins mixed-species flocks. It is a very active species that constantly moves through the foliage using short flights. It mainly feeds in the outer parts of the vegetation, making rapid movements and frequently changing perches. Its song is characterized by a distinctive series of four very high-pitched ascending notes.
Nesting: The reproductive biology of the species remains poorly known, and detailed descriptions of the nest and clutch are not available.
Conservation status: Classified internationally as Least Concern (LC), although in Argentina it is considered Vulnerable (VU). Its national distribution is limited and closely linked to the humid montane forests of the Yungas, a naturally restricted habitat within the country. It occurs in protected areas such as Calilegua National Park in Jujuy.
Authors of this compilation: María Belén Dri and Diego Carús – 05/31/2026