The rufous-rumped antwren (Euchrepomis callinota) is a species of passerine bird in the subfamily Euchrepomidinae of the family Thamnophilidae, the "typical antbirds." It is a small, canopy-dwelling insectivore with a highly disjunct distribution across Central and South America.
Taxonomy
The rufous-rumped antwren was described by the English zoologist Philip Lutley Sclater in 1855 and given the binomial name Formicivora callinota. It was transferred to the genus Terenura in 1885. It remained there until the genus Euchrepomis was created in 2012 by Gustavo Bravo and colleagues, following phylogenetic analysis.
Four subspecies are generally recognized:
- Euchrepomis callinota callinota (Sclater, PL, 1855)
- Euchrepomis callinota peruviana (Meyer de Schauensee, 1945)
- Euchrepomis callinota venezuelana (Phelps, WH & Phelps, WH Jr, 1954)
- Euchrepomis callinota guianensis (Blake, 1949)
The genus name Euchrepomis is derived from Greek elements meaning "fine complexion" and "point of the shoulder"; the specific epithet callinota is reported as combining Greek kallos ("beauty") and noton ("back").
Description
The rufous-rumped antwren is 10 to 12 cm (3.9 to 4.7 in) long and weighs about 7 to 9.5 g (0.25 to 0.34 oz). It is small, slender, and long-tailed, and somewhat resembles a greenlet or New World warbler. The sexes have different plumage.
Adult males of the nominate subspecies have blackish lores and an eye-line on an otherwise pale gray face. Their crown and nape are black, the upper back is olive, the lower back and rump are bright rufous or orange-brown, and the uppertail coverts are olive. The tail is dusky with olive edges on the feathers. The wing coverts are slate gray with pale yellow tips forming two wing bars; the flight feathers are dusky with olive edges. The throat and breast are pale gray, and the belly and undertail coverts are pale yellow-green. Adult females have a brownish-olive crown and grayish-olive sides of the head and lack the black cap. In both sexes the iris is brown or dark brown, the maxilla is black, the mandible is shades of gray with a black tip, and the legs and feet are bluish gray or gray.
Subspecies differ subtly. E. c. peruviana is similar to the nominate but has a yellowish-green tinge on the lower breast. E. c. venezuelana is known well only from the holotype, a female, which has a darker nape and upper back, a whiter throat, and a paler yellow belly. E. c. guianensis has a darker and richer olive back than the nominate, with brighter yellow on the wing coverts.
Distribution and habitat
The species has a markedly disjunct range. The nominate subspecies is the most widespread and occurs in several separate populations: on the eastern slope of the Cordillera de Talamanca in Costa Rica and Panama; in the Serranía del Darién and Santander department of Colombia, south along the west slope of the Andes into Ecuador; and on the east slope of the Andes into northern Peru. E. c. peruviana occurs south of the Marañón River in central and southeastern Peru. E. c. venezuelana is found in the Serranía del Perijá on the Colombia–Venezuela border and in the Venezuelan Andes. E. c. guianensis occurs in southern Guyana, central Suriname, and central French Guiana.
The bird inhabits the interior and edges of humid foothill and montane forest. Elevational ranges vary by region, reported at roughly 700 to 1,200 m in Costa Rica, 700 to 2,500 m in Colombia, 900 to 1,800 m in Ecuador, and largely 1,050 to 2,000 m in Peru, with some populations occurring at lower elevations. It is a year-round resident throughout its range.
Behaviour
The rufous-rumped antwren feeds on arthropods, though details of its diet are lacking. It typically forages in pairs that often join mixed-species feeding flocks, working almost entirely in the forest canopy and acrobatically gleaning prey from leaves and sticks. In Costa Rica the breeding season appears to run from February through May; little else is known of its breeding biology. Its song is described as a rapidly uttered, high-pitched series of notes that accelerates into a fast trill or chipper, and its calls include high "tsi" and "ti" notes.
Status
The International Union for Conservation of Nature (IUCN) has assessed the rufous-rumped antwren as Least Concern. It has a very large range, and the population is estimated at 50,000 to 499,999 mature individuals, though the trend is believed to be decreasing. No immediate threats have been identified, but the species is considered vulnerable to habitat loss and degradation from forest clearing for agriculture. It is described as rare in Costa Rica and uncommon in Colombia, Ecuador, and Peru.
