<trp-post-container data-trp-post-id='359771'>Rufous-margined Antwren

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En bref

  • Scientific Name: Herpsilochmus rufimarginatus
  • Spanish Name: Hormiguerito pechinegro
  • Family: Thamnophilidae
  • Known Nicknames: Rufous-winged Antwren, Rufous-margined Antshrike (misnomer)
  • Average Length: 10–11.5 cm / 3.9–4.5 in
  • Average Weight: 8–11 g / 0.28–0.39 oz
  • Wingspan: 15–18 cm / 5.9–7.1 in
  • Key Feature: Male has black crown and nape with white supercilium; female has rufous crown; both sexes show rufous edges on flight feathers and tail
  • Régime alimentaire principal : Principalement insectivore
  • Range: Southeastern Brazil
  • Habitat: Tropical lowland and foothill forests, especially canopy and subcanopy of humid forest and forest edges
  • Social Structure: Usually seen in pairs or small family groups, often joining mixed-species foraging flocks
  • Nesting/Breeding: Small cup-shaped nest placed in a fork of a tree branch
  • Statut de conservation : Préoccupation mineure (LC)
  • Évolution démographique : Stable

The Rufous-margined Antwren (*Herpsilochmus rufimarginatus*) is a small, energetic insectivore of South American lowland forests, easily identified by its striking plumage pattern. Males are predominantly gray above with a bold black cap and white underparts, while females display a warm rufous crown and back; both sexes share the species' most distinctive feature: bright rufous edges on the flight feathers and tail, creating a flash of cinnamon color in flight. This antwren is a specialist of vine tangles and mid-story canopies, where it often joins mixed-species foraging flocks, gleaning insects with quick, acrobatic movements. Its call is a rapid, high-pitched trill, and it is notable for its subtle sexual dimorphism and preference for terra firme and foothill forests, making it a lively, colorful addition to the avian community of the Amazon and Atlantic Forest regions.

Faits amusants

This tiny antwren has a bizarre habit of "anting," where it rubs ants—or even toxic millipedes—on its feathers to use the chemicals as a natural insecticide or fungicide. Males perform a unique "flutter-display" during courtship, rapidly quivering their wings while singing to show off their bright rufous wing patches. Despite being only 11 cm long, it fearlessly mobs larger predators like toucans, often joining mixed-species flocks to act as a sentinel. Its nest is a deep pouch woven from spiderwebs and plant fibers, suspended from a branch like a tiny hammock, and the female lays just two eggs that are pure white with bold black speckles.

Habitats et répartition

The Rufous-margined Antwren inhabits the lower to middle levels of humid tropical and subtropical forests, including both terra firme and seasonally flooded lowland forests, as well as forest edges and mature secondary growth. It strongly favors areas with dense vine tangles and epiphyte-laden branches, often near watercourses, but avoids open or heavily disturbed habitats. Its geographical range spans the Amazon Basin in Brazil, Peru, Ecuador, Colombia, Venezuela, and the Guianas, extending south into northern Bolivia and east into the Atlantic Forest of eastern Brazil.

Comportements & Reproduction

The Rufous-margined Antwren is typically observed in monogamous pairs that defend small territories within the humid forest canopy. Its social structure is simple, with pairs foraging together in mixed-species flocks, though they remain largely independent of other antwren groups. Mating involves the male performing a series of quick, ascending songs and wing-fluttering displays to court the female. Reproduction centers on a unique strategy of building a deep, hanging pouch-nest, often suspended from a thin forked branch, which helps protect eggs and chicks from arboreal predators. The female lays two white eggs marked with brown spots, and both parents share incubation duties for about 14-16 days. After hatching, the adults cooperatively feed the nestlings, and the young fledge after roughly 11-12 days, remaining dependent on the parents for several more weeks before dispersing.

Alimentation

The Rufous-margined Antwren is primarily an insectivore, with its diet consisting almost entirely of small arthropods. It is an active and agile forager, typically gleaning prey from the undersides of leaves and branches in the forest canopy and subcanopy. Studies of its stomach contents have revealed a preference for various insects, including beetles, caterpillars, ants, and spiders. A particularly interesting aspect of its feeding behavior is its participation in mixed-species foraging flocks; it frequently joins groups of other insectivorous birds to increase foraging efficiency, capitalizing on the disturbance created by other species to flush out hidden prey.

Couleurs

The male Rufous-margined Antwren has a black crown and nape with white spots, a white supercilium, and black eyestripe, while the female has a rufous crown. Both sexes display a distinctive rufous edge to the wing and tail feathers, contrasting with white underparts and a gray back. This coloration provides camouflage against dappled light in the forest canopy, with the rufous margins breaking up the bird’s outline among leaves and branches.

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