Oustalet’s Tyrannulet

Quick Facts

• Scientific Name: Phyllomyias oustaleti
• Spanish Name: Tiranuelo de Oustalet
• Family: Tyrannidae
• Known Nicknames: Oustalet's Flycatcher, Oustalet's Tyrant
• Average Length: 11–12 cm / 4.3–4.7 in
• Average Weight: 8–11 g / 0.28–0.39 oz
• Wingspan: N/A
• Key Feature: Small, olive-green upperparts and pale yellowish underparts with a short, thin bill
• Primary Diet: Primarily Insectivore
• Range: Southeastern Brazil (from Bahia to Santa Catarina)
• Habitat: Atlantic Forest, especially humid montane and lowland forests, forest edges, and secondary growth
• Social Structure: Solitary or in pairs
• Nesting/Breeding: Small cup nest in a tree fork
• Conservation Status: Least Concern (LC)
• Population Trend: Decreasing

The Oustalet's Tyrannulet (*Phyllomyias oustaleti*) is a small, active songbird native to the Atlantic Forest of southeastern Brazil, known for its subtle beauty and energetic foraging style. Its general appearance is a soft olive-green above with a slightly paler, yellowish-tinged belly and throat, accented by two faint, pale wingbars and a short, thin bill. A unique characteristic of this species is its strong preference for the upper canopy of humid montane forests, where it often joins mixed-species flocks, flitting nervously among leaves in search of insects. Special features include a relatively long tail compared to other tyrannulets and a distinctive, high-pitched, trilling call that is often the best clue to its presence, as its drab coloration can make it easy to overlook against the dappled forest light.

Fun Facts

Despite its tiny size, Oustalet's Tyrannulet has a surprisingly loud, buzzy call that often betrays its presence before it’s spotted high in the canopy. It exhibits a quirky foraging behavior called "sally-gleaning," where it hovers briefly to pluck insects from leaf undersides rather than simply picking them from a perch. A unique adaptation is its unusually short, slender bill for a tyrant-flycatcher, which suggests a specialized diet of very small arthropods and soft fruits. This species also engages in a peculiar "wing-flicking" display during territorial disputes, rapidly snapping its wings open and shut to flash pale feather patches at rivals.

Habitats & Distribution

Oustalet's Tyrannulet is found in a relatively restricted region of southeastern Brazil, primarily within the coastal Atlantic Forest biome. Its habitat consists of humid, montane forests, typically occurring at elevations between 600 and 1,800 meters. It inhabits the canopy and subcanopy layers of primary and mature secondary forests, often favoring areas with abundant epiphytes and moss. The species has a patchy distribution from the state of Bahia south to northern Santa Catarina, with its core range centered on the Serra do Mar and Serra da Mantiqueira mountain ranges.

Behaviours & Reproduction

Oustalet's Tyrannulet is generally solitary or observed in pairs during the breeding season, with no evidence of complex social structures or cooperative breeding. Its mating habits are poorly documented, but like most tyrant flycatchers, it is presumed to be monogamous for a given season. Reproduction involves the construction of a small, cup-shaped nest, often placed in a tree fork and camouflaged with lichen and moss. The female typically lays two eggs, and both parents share incubation and feeding duties. A notable reproductive strategy is its use of a shallow nest in exposed sites, which may reduce predation by making the nest less accessible to arboreal snakes, while the cryptic coloration of both nest and eggs provides passive defense. No unique strategies such as brood parasitism or extended parental care beyond fledging have been recorded.

Diet

Oustalet's Tyrannulet is primarily an insectivore, with its diet consisting almost entirely of small arthropods such as beetles, caterpillars, ants, and spiders. An interesting fact about its feeding behavior is that it employs a "gleaning" technique, actively hopping through the mid- to upper-canopy of humid montane forests and systematically plucking prey from the undersides of leaves and branches, often while hanging upside down. Unlike many flycatchers, it rarely engages in sustained aerial sallies, instead making short, quick lunges to snatch stationary or slow-moving insects. Another notable detail is that it has been observed joining mixed-species foraging flocks, allowing it to exploit a wider array of prey by following larger birds that flush insects from foliage.

Colors

Oustalet's Tyrannulet is primarily olive-green above with a pale yellow throat and belly, and a faint grayish crown. It has two subtle pale wing bars and a slight whitish eye-ring. Its muted, countershaded coloration provides camouflage in the dappled light of its forest canopy habitat, with no unique patterns or bold markings.