Chestnut-backed Antshrike Thamnophilus palliatus Scientific name definitions

Occupying a highly disjunct range that stretches from central and southeast Peru to northern Bolivia thence, rather narrowly, through central and eastern Amazonian Brazil, with a wholly separate population in the Brazilian Atlantic Forest region, the Chestnut-backed Antshrike is currently recognized to comprise four subspecies. These differ only relatively slightly in the warmth and intensity of the color of the upperparts. The Chestnut-backed Antshrike was formerly considered conspecific with the Lined Antshrike (Thamnophilus tenuepunctatus) of the eastern foothills of the Andes, but the two meet species in Peru with no evidence of intergradation. A boldly plumaged bird, typically found in pairs, both sexes of this antshrike have a rufous back, wing and tail, and broadly black and white-barred underparts, with males also having a black crown, which is replaced by rufous in females. The Chestnut-backed Antshrike generally occurs in lighter woodland, forest borders, plantations, and tall second growth, and occurs to at least 2200 m.

16–17 cm; 26–28 g. Male has black crown, forehead spotted white, black side of head and nape spotted white; upper­parts, wings and tail rufous-brown; throat striped black and white, remaining underparts barred black and white, flanks tinged rufous. Female is like male, but crown deep rufous-brown, light bars on underparts wider. Subadult male resembles adult male, but forehead mixed black and deep reddish-brown, light bars below tinged reddish-brown posteriorly; subadult female is like female, but dark stripes of throat and dark bars of underparts narrower, rear underparts strongly washed yellow-ochre. Races differ only slightly in intensity and warmth of upperpart colours, relative width of dark and light bars below, and measurements: similis resembles nominate; <em>puncticeps</em> has upperparts and underparts paler, female nape strongly suffused yellow-ochre; <em>vestitus</em> is paler above than previous, darker with broader dark bars below.

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Editor's Note: Additional distribution information for this taxon can be found in the 'Subspecies' article above. In the future we will develop a range-wide distribution article.

Understorey and mid-storey of evergreen-forest borders, taller second growth, regenerating clearings and plantations, and lighter woodland. Andean populations occur primarily from 1000 m to 2200 m, descending to lowlands in C Bolivia, and most often found at forest edges and clearings with regenerating bamboo. Lowlands in Amazonia, where often in vine-covered trees and shrubs at forest edge and second growth, and in mixed areas of trees and bamboo; in some localities almost restricted to extensive stands of Guadua bamboo. Much more of a generalist in coastal E Brazil, and found in shrubby borders of parks and gardens, regenerating plantations and clear-cuts, and at edges of both uncut and degraded evergreen forest, with or without bamboo; to 1000 m, mostly below 300 m.

None recorded; presumed resident throughout range.

Little published. Feeds chiefly on insects , including orthopterans such as grasshoppers (Acrididae), katydids (Tettigoniidae), stick-insects (Phasmatidae) and mantids (Mantidae), beetles (Coleoptera), ants, bees and wasps (Hymenoptera), true bugs (Hemiptera, Homoptera); and lepidopteran larvae; as well as other arthropods, such as spiders. Stomach contents of specimen from Brazil (Pará) included hemipterans, homopterans (Cicadidae), coleopterans (Chrysomelidae, Curculionidae), hymenopterans (Formicidae, Vespoidea, Apoidea) and dipterans (Brachycera). Forages in pairs or individually, in thickets, vine tangles, and in dense canopy foliage of second-growth trees, usually remaining in heavy cover; in much of Amazonia, primarily above 6 m in tangled crowns of bamboo in middle storey, climbing higher to forage in central vine tangles and dense upperstorey foliage of emergent trees (to 15 m). Progresses by short hops, separated by pauses of 1–10 seconds to scan for prey; often hitches from side to side when working upwards through tangles. Reaches out, up and down, or lunges to glean prey from all leaf, stem, vine and branch surfaces with quick stabbing motion of the bill. Often associated, at least loosely, with mixed-species flocks moving through stands of bamboo or tall second growth in its home range. In Andes and SE Brazil, where more a bird of forest edge and scrubby second growth, forages in similar fashion but more often lower, 1–5 m above ground, in dense, shrubby thickets, although sometimes climbs to canopy of mid-storey trees at forest edge; and seldom associated with mixed-species flocks. Recorded as attending swarms of army ants (Eciton burchelli) in E Brazil, and seen to supplant Pyriglena leuconota at one such swarm; generally follows ants only through dense understorey thickets at forest edge, then abandons them when ants move into more open areas in interior.

Loudsong a moderately long (e.g. 20 notes, 2·5 seconds), accelerating series of similar, rapidly delivered, somewhat nasal notes, pitch rising slightly initially, more clearly falling towards end, terminating in longer, firmly accented, downslurred note. Calls include emphatic short nasal note and longer, upward-inflected, squeal.

In Brazil, breeds Oct–Jan in SE and, in NE (Pará), female feeding fledgling in Jun near Belém and nest-building in Nov near mouth of R Tapajós. Nest a small, deep cup loosely constructed from fine, well-interlaced filaments, those of outside much darker, almost black roots or fungus, sometimes decorated with green moss, internal ones yellowish and almost entirely shafts of herbs and fine flower peduncles, sometimes also with “horsehair”, the whole attached by rim at 1·5–3 m in horizontal fork among foliage in thicket. Normal clutch 2 eggs, creamy to reddish-white, with irregular purplish, dark brown or reddish-brown spots, blotches and lines most dense at blunt end, almost no markings at pointed end.

Not globally threatened (Least Concern). Locally fairly common over much of its extensive range. This includes several protected areas, e.g. Tapajós and Tijuca National Parks, Cristalino State Park and Sooretama Biological Reserve, in Brazil, and Tambopata-Candamo Reserved Zone and Manu National Park and Biosphere Reserve, in Peru. Adapted to a variety of habitats, including highly disturbed woodland and second growth, rendering it of low vulnerability. It is apparently expanding to the south in SE Brazil, were recorded in 2007 at Ubatuba, São Paulo (4 Santos, A.S.R., Olmos, F. and Souza, R.C.R. (2009). Thamnophilus palliatus (Thamnophilidae): registro documentado de uma nova espécie colonizadora no litoral de São Paulo – BR. Atualidades Ornitológicas. 147: 14. Close ).