- Order: Passeriformes
- Family: Thamnophilidae
- Polytypic 4 Subspecies
Euchrepomis are small, slender, long-tailed canopy antwrens, superficially resembling a greenlet (Vireonidae) or wood-warbler (Parulidae). As with other members of the genus, male and female Rufous-rumped Antwrens differ in plumage. The head and throat of the male are pale gray, with a contrasting black crown. The upper back is olive, but the lower back and the rump are bright rufous. The wings are dusky, with two yellowish wing bars, and the remiges are margined with olive. The belly and undertail coverts are pale yellow or yellowish green. The female resembles the male but the crown and upper back are brownish olive.
Rufous-rumped Antwren has very little overlap with other species of Euchrepomis. In Ecuador and Peru the Andean distribution of Rufous-rumped broadly abuts that of Chestnut-shouldered Antwren (Euchrepomis humeralis) of Amazonia, but these two species rarely if ever are syntopic; Rufous-rumped rarely occurs below 1000 m, while Chestnut-shouldered only occurs in the lowlands, below 650 m. Male Chestnut-shouldered also has rufous or chestnut lesser wing coverts; females of the two species are much more similar, however. Very locally, in Cuzco, Rufous-rumped Antwren overlaps with Yellow-rumped Antwren (Euchrepomis sharpei), a species that geographically replaces Rufous-rumped in far southeastern Peru and in Bolivia. Both sexes of Yellow-rumped have bright yellow, not rufous, on the lower back and rump. Male Yellow-rumped also has more extensive and conspicuous bright yellow on the lesser wing coverts. Where both species overlap, in Cuzco, the known elevational range of Rufous-rumped is 750-1000 m, whereas Yellow-rumped is reported from higher elevations, at 1000-1550 m (Walker et al. 2006).
The song of Rufous-rumped Antwren is typical of the genus Euchrepomis, and is described as "a rapidly uttered, high-pitched tsii-tsii-tsi-tsi-titititititititi that accelerates into a fast chipper or trill" (Ridgely and Greenfield 2001b) and as "an accelerating, rising series of high, thin notes ending in a falling, chippering trill: tew tew-tew-ti-ti-ti't't't't't't'ti" (Lane, in Schulenberg et al. 2010). This song sometimes is answered by a similar, but slower, song, which perhaps is given by the female (Lane, in Schulenberg et al. 2010).
Calls of Rufous-rumped Antwren include high tsi and ti notes (Lane, in Schulenberg et al. 2010).
Detailed Description (appearance)
The following description is based on Zimmer and Isler (2003) and on specimens in the Louisiana State University Museum of Natural Science, and refers to nominate callinota; see also Geographic Variation:
Adult male: Crown and nape black. Back olive, with concealed creamy interscapular patch. Lower back and rump bright rufous or orange brown; sometimes the feathers of the center of the back are black on the inner webs. Uppertail coverts olive. Rectrices dusky, edged with olive. Wing dusky, remiges edged with olive. Greater and median wing coverts slate gray tipped pale yellow (forming two bars); anterior lesser wing coverts (usually concealed) and underwing coverts bright yellow. Lores, supercilium, and sides of head and of neck pale gray. Throat and breast pale gray, belly and undertail coverts pale yellow green.
Female: Much like male, but crown brownish olive, and the sides of the head are grayish olive. Lacks the creamy interscapular patch. The yellow shoulder is absent.
Iris: brown, dark brown
Bill: maxilla black; mandible gray, silver gray, or blue gray with a black tip
Tarsus and toes: bluish gray, gray
Bare parts color data from Mees (1974), Stiles (1983), Robbins et al. (1985), Robbins and Ridgely (1990), and from specimens in the Louisiana State University Museum of Natural Science.
Total length: 10.7 cm (Hilty and Brown 1986), 11 cm (Ridgely and Greenfield 2001b, Schulenberg et al. 2010), 11.5 cm (Stiles and Skutch 1989)
Linear measurements (from Wetmore 1972):
male (n = 3)
wing length: mean 50.3 mm (range 480-53.2 mm)
tail length: mean 40.9 mm (range 37.5-44.8 mm)
bill length (culmen from base): mean 13.6 mm (range 13.5-13.8 mm)
tarsus length: mean 15.6 mm (range 14.7-16.6 mm)
female (n = 8)
wing length: mean 52.1 mm (range 49.9-53.7 mm)
tail length: mean 41.7 mm (range 35.5-47.2 mm)
bill length (culmen from base): mean 13.9 mm (range 13.3-15.6 mm)
tarsus length: 15.4 mm (range 14.9-16.1 mm)
Mass: male, mean 7.8 g (range 7.2-8.5 g, n = 8); female, mean 7.8 (range 7-9.4 g, n = 7) (data from Stiles 1983, Robbins et al. 1985, Robbins and Ridgely 1990, and from specimens in the Louisiana State University Museum of Natural Science.
Generally, antbirds (Thamnophilidae) follow the Complex Basic molt strategy, with an incomplete preformative molt (Ryder and Wolfe 2009), but there is very little specific information on molts of Rufous-rumped Antwren. One specimen, not in breeding condition, showed heavy molt on the back, but only light molt elsewhere (Robbins and Ridgely 1990).
Four subspecies usually recognized:
callinota, described as Formicivora callinota Sclater 1855; type locality Bogotá, Colombia
Occurs from Costa Rica south to Colombia, Ecuador, and northernmost Peru.
See Detailed Description.
venezuelana, described as Terenura callinota venezuelana Phelps and Phelps 1954; type locality Cerro Pejochaina, upper Río Negro, Sierra de Perijá, Zulia, Venezuela
Occurs in the Sierra de Perijá, on the Colombia/Venezuela border; the population in the Andes of Venezuela presumbably also is this subspecies.
Known in detail only from the female holotype, which is similar to female of nominate callinota but "nape and scapulars darker, olivaceous gray instead of bright olive; throat whiter, purer grayp abdomen paler yellow; lores more whitish, less buffy or brownish; wing band whiter; tail and bill longer" (Phelps and Phelps 1954).
guianensis, described as Terenura callinota guianensis Blake 1949; type locality Boundary Camp, head of Itabu Creek, Acari Mountains, Guyana. Hylophilus puellus (Mees 1974) is a junior synonym (Mayr and Vuilleimier 1983).
Occurs locally in montane areas in southern Guyana and southern Suriname.
Similar to nominate callinota, but the lower and back are darker and richer; bend of the wing and lesser wing coverts slightly darker and more intense yellow; and interscapular patch reduced or absent (Blake 1949, Zimmer and Isler 2003).
peruviana, described as Terenura callinota peruviana Meyer de Schauensee 1945; type locality Río Jelashte, San Martín, Peru
Occurs in Peru, south of the Marañón River, south to Cuzco.
Similar to nominate callinota, but breast, especially the lower breast, tinged with yellowish green (not pale grayish), and so the gray breast is less sharply defined from the greenish yellow belly (Meyer de Schauensee 1945).
Specimens of Euchrepomis formerly were rare in collections, and these taxa were even less well known than currently is case. During this period some authors (e.g. Zimmer 1932) suggested that callinota and Euchrepomis humeralis (Chestnut-shouldered Antwren) were conspecific, but all modern authors readily recognize montane callinota and Amazonian humeralis as separate species.
Taczanowski and Berlepsch (1885) transferred callinota from Formicivora to Terenura (type species maculata, Streak-capped Antwren), and this classification was widely followed until recently. A phylogenetic analysis of DNA sequence data, from both mitochondrial and nuclear genes, reveals, however, that callinota and related species (humeralis; sharpei, Yellow-rumped Antwren; and spodioptila, Ash-winged Antwren) are not all closely related to species of Terenura (Bravo et al. 2012). These four species are the sister group to all other species of thamnophilid antbirds; as no generic name was available, Bravo et al. (2012) proposed the name Euchrepomis (type species callinota) for this group.
Schulenberg, Thomas S. 2015. Rufous-rumped Antwren (Euchrepomis callinota), Neotropical Birds Online (T. S. Schulenberg, Editor). Ithaca: Cornell Lab of Ornithology; retrieved from Neotropical Birds Online: http://neotropical.birds.cornell.edu/portal/species/overview?p_p_spp=385011