The spot-backed antbird is 10.5 to 11.5 cm (4.1 to 4.5 in) long and weighs 11 to 14 g (0.39 to 0.49 oz). Adult males of the nominate subspeciesH. n. naevius have a dark yellowish brown crown and nape. Their upperparts are mostly dark yellowish brown; the center of their back is black with pale buff spots and they have a white patch between their scapulars. Their flight feathers are dark brown with black bases and their wing coverts black with wide white to pale buff tips. Their tail is dark reddish yellow-brown with white to pale buff tips and a black band above the tips. The face is mostly gray; their throat and the lower sides of their neck are black. Their underparts are mostly white with heavy black spots across the breast and along the sides. Their lower belly and undertail coverts are buff. Adult females are similar to males but have paler upperparts, buffier wing coverts, a white throat with a black band above it, and buff rather than white underparts with the same heavy black spots as males. Juveniles have no interscapular patch, no breast spots, and buffy brown underparts with an olive-brown band across the breast.[11][14][15][16][17][18]
The other subspecies of the spot-backed antbird differ from the nominate and each other thus:[11][14][15][16][17][18]
H. n. peruvianus: grayer crown, more chestnut upperparts with more black area and paler spots, and more and bigger breast spots than nominate
H. n. theresae: purer gray crown and more black on the back than peruvianus; olive-tinged gray tail with wider pale tip than nominate, more breast spots than nominate, and light olive-buff belly and undertail coverts
H. n. inexpectatus: olive-gray crown, olive-brown back, and dark olive-gray tail
H. n. ochraceus: grayish crown, small interscapular patch, small to no breast spots; male has ochre-yellow belly and undertail coverts and female has mostly ochre-yellow underparts
Distribution and habitat
The subspecies of the spot-backed antbird are found thus:[11][15][16][18]
H. n. theresae: southeastern Ecuador south of the Rio Napo, Loreto Department in northeastern Peru, and western Amazonian Brazil south of the Amazon east to the Rio Tapajós and south to Rondônia
H. n. peruvianus: Amazonas and San Martín departments in north-central Peru
H. n. inexpectatus: east-central and southeastern Peru, Acre (state) in southwestern Brazil, and northwestern Bolivia
H. n. naevius: southeastern Colombia south through eastern Ecuador into northern Peru and east through southern Venezuela, the Guianas, and northern Brazil north of the Amazon to the Atlantic
H. n. ochraceus: Amazonian Brazil south of the Amazon between the rios Tapajós and Tocantins and south into northern Mato Grosso
The spot-backed antbird inhabits humid evergreen forest in the lowlands and Andean foothills. It is found in terra firme, várzea, and transitional forest types as well as secondary woodlands. It favors the forest understorey especially near openings caused by fallen trees and along watercourses. In elevation it reaches 1,100 m (3,600 ft) in Venezuela and Colombia, 1,300 m (4,300 ft) in Brazil, and 1,200 m (3,900 ft) in Peru. A few individuals reach 1,000 m (3,300 ft) in Ecuador but it is mostly found below 700 m (2,300 ft) there.[11][14][15][16][17][18]
Behavior
Movement
The spot-backed antbird is believed to be a year-round resident throughout its range.[11]
Feeding
The spot-backed antbird feeds primarily on a wide variety insects and spiders. It is a facultativearmy ant follower, catching about half of its prey as it flees the swarms but seldom following them for a long time. They sometimes loosely associate with mixed-species feeding flocks. They forage as individuals, pairs, and small family groups and mostly within about 3 m (10 ft) of the ground. They hop among branches, typically in semi-open parts of the understorey, and take prey with sallies from a perch to the ground and by gleaning and lunging for prey on leaves, twigs, and branches.[11][14][15][17]
Breeding
The spot-backed antbird's core breeding season varies geographically but overall the species appears to breed at any time of year. Its nest is a cup made variously of grasses, palm "hairs", fern rootlets, or
fungal rhizomes. It is typically suspended from a branch fork near the ground and often partially or fully covered by hanging leaves. The most common clutch size is two eggs though there are many records of nests with one or three. Both parents incubate though it appears that the female alone does so at night, and both parents are assumed to brood and provision nestlings. The incubation period is not known; at one nest fledging occurred 12.5 days after hatch.[11]
The spot-backed antbird's song varies among the subspecies; it is generally "a long series of doublets".[11] In Ecuador it is described as "a fast, high-pitched, and somewhat wheezy 'wur, weépur-weépur-weépur-weépur-weépur-weépur-weépur-weépur'...loudest in the middle and fading at end".[15] In Brazil, where several subspecies are found, it is "[v]ery/extr. high, slightly descending series of 10-12 strident, run together 'tjuwit- notes; depending on region, 'tjuwit-' sounding as double note or reduced to 'tWit---' ".[18] The species' calls "include abrupt, spitting notes, almost always in groups of 2–10; a rattle of variable length, usually descending in pitch; and [a] long (e.g. 0·2–0·4 seconds) downward-inflected whistle".[11]
Status
The IUCN has assessed the spot-backed antbird as being of Least Concern. It has a very large range; its population size is not known and is believed to be stable. No immediate threats have been identified.[1] It is considered fairly common to common in much of its range though uncommon to fairly common in Venezuela and Peru.[11][16][17] It is found in several protected areas in almost all of the countries it inhabits.[11]
^Remsen, J. V., Jr., J. I. Areta, E. Bonaccorso, S. Claramunt, G. Del-Rio, A. Jaramillo, D. F. Lane, M. B. Robbins, F. G. Stiles, and K. J. Zimmer. Version 4 March 2024. Species Lists of Birds for South American Countries and Territories. https://www.museum.lsu.edu/~Remsen/SACCCountryLists.htm retrieved 5 March 2024
^Clements, J. F., P.C. Rasmussen, T. S. Schulenberg, M. J. Iliff, T. A. Fredericks, J. A. Gerbracht, D. Lepage, A. Spencer, S. M. Billerman, B. L. Sullivan, and C. L. Wood. 2023. The eBird/Clements checklist of birds of the world: v2023. Downloaded from https://www.birds.cornell.edu/clementschecklist/download/ retrieved October 28, 2023
^ abcdefghijklZimmer, K. and M.L. Isler (2020). Spot-backed Antbird (Hylophylax naevius), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.spbant6.01 retrieved July 24, 2024
^Boesman, P. (2016). Notes on the vocalizations of Spot-backed Antbird (Hylophylax naevius). HBW Alive Ornithological Note 60. In: Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona.
^Zimmer, K.J., and M.L. Isler. 2003. Family Thamnophilidae (typical antbirds). Pp. 448-681 in "Handbook of the Birds of the World, Vol. 8. Broadbills to Tapaculos." (J. del Hoyo, A. Elliot, and D.A. Christie, eds.). Lynx Edicions, Barcelona.
^ abcdMcMullan, Miles; Donegan, Thomas M.; Quevedo, Alonso (2010). Field Guide to the Birds of Colombia. Bogotá: Fundación ProAves. p. 140. ISBN978-0-9827615-0-2.
^ abcdefRidgely, Robert S.; Greenfield, Paul J. (2001). The Birds of Ecuador: Field Guide. Vol. II. Ithaca: Cornell University Press. p. 420. ISBN978-0-8014-8721-7.
^ abcdeSchulenberg, T.S., D.F. Stotz, D.F. Lane, J.P. O’Neill, and T.A. Parker III. 2010. Birds of Peru. Revised and updated edition. Princeton University Press, Princeton, New Jersey. Plate 175.
^ abcdeHilty, Steven L. (2003). Birds of Venezuela (second ed.). Princeton NJ: Princeton University Press. pp. Plate 44.
^ abcdevan Perlo, Ber (2009). A Field Guide to the Birds of Brazil. New York: Oxford University Press. pp. 260–261. ISBN978-0-19-530155-7.