White-rimmed Warbler

Belongs to the Parulidae family and is scientifically known as Myiothlypis leucoblephara. This small, elegant passerine measures between 11.5 and 12.5 centimeters in length and weighs approximately 10 to 14 grams. Its plumage displays a distinct contrast highlighted by a striking white supercilium (eyebrow) starting from the base of the bill, bordered above by dull blackish lateral crown stripes. The upperparts are a uniform olive-gray, whereas the underparts are mostly white, transitioning to a soft gray on the flanks and displaying subtle yellowish undertones on the lower abdomen. It features dark brown eyes and distinctively pale pinkish legs. There is no obvious sexual dimorphism, meaning males and females share the same coloration.

Geographical distribution: This species is endemic to the southern cone of South America, with a distribution range encompassing southeastern and southern Brazil (extending from Minas Gerais and Espírito Santo down to Rio Grande do Sul), eastern Paraguay, northeastern Argentina (particularly in Misiones, Corrientes, and Entre Ríos provinces, sometimes reaching northern Buenos Aires), and throughout Uruguay.

Habitat: It primarily occupies the dense understory of humid subtropical forests, gallery forests, swampy woodlands, thickets, and secondary growth areas. It displays a strong preference for damp environments near watercourses, shaded ravines, and humid valleys where thick, low-lying vegetation provides excellent cover against predators.

Feeding: Its diet is strictly insectivorous. It actively searches for and consumes a wide variety of small invertebrates, including beetles, flies, spiders, caterpillars, and other insects. It forages primarily in the leaf litter of the forest floor or low foliage, using quick hops and short, precise flights to capture active prey.

Behavior: This highly energetic and territorial bird usually moves solitary or in pairs within the lower strata of the forest, rarely ascending to the canopy. It possesses a characteristic habit of hopping rhythmically while constantly flicking its tail up and down or sideways. It is widely known for its melodious and loud whistling song, which consists of a series of rising and falling notes that resonate through the dense vegetation, serving to define territories and strengthen pair bonds. It occasionally joins mixed-species flocks during foraging.

Nesting: The breeding season occurs during the austral spring and summer. It constructs a dome-shaped or oven-like nest with a side entrance, using dry grasses, fallen leaves, moss, and fine roots. The nest is built directly on the forest floor, masterfully concealed among dead leaves, roots, or vegetated banks. The female typically lays 3 to 4 white eggs speckled with small reddish-brown spots concentrated at the larger end. Incubation lasts about two weeks, and both parents share the duties of feeding and protecting the nestlings.

Conservation status: It is currently classified as Least Concern (LC) on the IUCN Red List of Threatened Species. Although its habitat suffers from fragmentation due to deforestation and agricultural expansion within the Atlantic Forest biome, its population remains stable, and the species exhibits adaptability to secondary forest habitats.