Southern Beardless-Tyrannulet

En bref

  • Scientific Name: Camptostoma obsoletum
  • Spanish Name: Tiranuelo Pechiamarillo
  • Famille : Tyrannidae
  • Known Nicknames: Southern Beardless Tyrannulet, Mosquerito Silbón, Tiranolete Silbador
  • Average Length: 9.5–11.5 cm / 3.7–4.5 in
  • Average Weight: 6–10 g / 0.21–0.35 oz
  • Envergure : N/A
  • Key Feature: Small, drab olive-gray plumage with a slight crest, pale yellowish belly, and a short, thin bill lacking rictal bristles
  • Primary Diet: Primarily Insectivore (also consumes small fruits and berries)
  • Range: Costa Rica and Panama through South America to central Argentina, northern Chile, and Uruguay
  • Habitat: Open woodlands, forest edges, secondary growth, gardens, and savanna with scattered trees
  • Structure sociale : Solitaires ou en couples
  • Nesting/Breeding: Small cup nest in a tree fork or branch, often concealed by moss or lichen
  • Statut de conservation : Préoccupation mineure (LC)
  • Évolution démographique : Stable

The Southern Beardless-Tyrannulet (*Camptostoma obsoletum*) is a small, energetic flycatcher that defies its name—it has a tiny, barely visible crest, not a beard, and is a master of vocal mimicry, often weaving the songs of other birds into its own varied calls. With a drab olive-brown back, pale yellowish belly, and a subtle white eyebrow stripe, it blends seamlessly into the canopies of South American forests and gardens. Its most unique feature is its habit of hovering to glean insects from leaves, combined with a specialized, brush-tipped tongue for sipping nectar and fruit pulp, making it a versatile forager that thrives from Costa Rica to Argentina.

Faits amusants

Despite its name, the Southern Beardless-Tyrannulet is not actually beardless—it lacks the conspicuous rictal bristles (stiff feathers around the beak) common in many flycatchers, relying instead on its sharp eyesight to snatch insects mid-air. It has a quirky habit of constantly flicking its wings and tail while foraging, a motion that seems to mimic leaf movement to startle hidden prey. One of its most unique adaptations is its ability to feed on small fruits and berries during the non-breeding season, a dietary flexibility rare among its primarily insectivorous tyrant-flycatcher relatives. It also builds a remarkable dome-shaped nest with a side entrance, often decorated with spider egg sacs or lichen for camouflage.

Habitats et répartition

This small flycatcher is found from Costa Rica south through Panama and across most of South America east of the Andes, including Colombia, Venezuela, the Guianas, Brazil, eastern Ecuador and Peru, Bolivia, Paraguay, and northern Argentina. It inhabits a wide variety of open to semi-open wooded environments, from dry deciduous forests and scrublands to gallery forests, forest edges, secondary growth, plantations, and urban gardens and parks. It is generally absent from the interior of dense, humid rainforest, preferring lighter woodland and areas with scattered trees.

Comportements & Reproduction

The Southern Beardless-Tyrannulet is generally solitary or found in loose pairs outside the breeding season, defending feeding territories within its forest-edge or woodland habitat. Mating is monogamous for a given season, with males attracting females through simple, repeated vocalizations rather than elaborate courtship displays. The female constructs a small, dome-shaped nest with a side entrance, often woven from plant fibers and spiderwebs, and suspended from a branch or vine. She lays two white eggs and performs the majority of incubation, which lasts about 14–15 days. Both parents feed the nestlings, which fledge after approximately 15–17 days. A unique reproductive strategy includes the frequent use of arboreal termite nests or abandoned nests of other birds as a foundation, providing structural support and camouflage. There is no evidence of cooperative breeding or brood parasitism within this species.

Alimentation

The Southern Beardless-Tyrannulet is primarily insectivorous, feeding on a wide variety of small arthropods such as flies, beetles, caterpillars, and spiders, which it typically gleans from foliage or catches in short, sallying flights. A fascinating aspect of its diet is that it also consumes small fruits and berries, particularly from mistletoe, figs, and other fruiting trees, making it an opportunistic omnivore that adjusts its intake seasonally. Unlike many tyrant flycatchers, it is known to hover briefly while picking insects from the undersides of leaves, and it occasionally joins mixed-species foraging flocks to exploit food sources more efficiently. Additionally, it has been observed eating small seeds and nectar on rare occasions, showcasing a flexible feeding strategy that helps it thrive in a range of habitats from dry forests to urban gardens.

Couleurs

The Southern Beardless-Tyrannulet is a small, drab flycatcher with olive-brown upperparts and pale yellowish-white underparts. It features a subtle whitish eyering, two faint buffy wingbars, and a slight, ragged crest. Its plumage provides excellent camouflage among foliage, blending into the dappled light of its forest-edge and woodland habitats.