Black-throated Antbird Myrmophylax atrothorax Scientific name definitions

The Black-throated Antbird has a somewhat curious geographical range, being widely distributed over much of Amazonia, except parts of the southeast and a large part of the central south; seven subspecies have been described (two of them not widely recognized), which differ chiefly in the extent of black underparts in males, and the depth and extent of rufous coloration below in females, but these differences do not seem to be matched by any vocal variation. Black-throated Antbirds are found in the understory of lowland evergreen forests, both on terra firme and in seasonally flooded areas, but seem to be nearly always associated with densely vegetated edge habitats. They feed on insects and spiders, and pairs and singles keep low above, or on, the ground, and apart from mixed-species foraging flocks (like most congenerics). Nesting behavior is still little known, and more data are required to adequately describe this aspect of the species’ biology.

13–14 cm; 14–18 g. Interscapular patch white. Male nominate race has crown and upperparts dark yellowish olive-brown, becoming blackish on rump; wing-coverts subterminally black, tipped white; tail blackish-grey; head side and underparts grey, centre of throat and breast black; underwing-coverts grey. Female differs from male in dull reddish yellow-brown crown and upperparts, dark brown wings, coverts tipped light buff, white chin and upper throat, remaining underparts cinnamon-rufous except flanks and crissum dark olive-brown; underwing-coverts yellowish olive-brown. Races vary in colour and darkness and plumage, and extent of black below on male: metae has black breast feathers edged grey, giving spotty appearance; tenebrosa is much darker above, wing-covert spots minute, male extensively black below, flanks and belly blackish-grey, female (said to be unknown, but old museum specimen recently located at AMNH) similar to nominate but darker all over; maynana male has upperparts sooty grey, faintly washed brownish; <em>melanura</em> differs from nominate in slender bill, more extensively grey forecrown and supercilium, olive or light russet-brown rump with sooty-grey uppertail-coverts, male belly paler, female belly white, but much variation, e.g. in E Peru and W Brazil darker above and male mostly black below (“obscurata”), on lower R Tapajós male black breast spotted white (“stictothorax”).

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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 of evergreen-forest edge (terra firme, transitional, várzea/igapó), second-growth woodland, and river-edge forest; mostly below 500 m, up to 1200 m in tepui region of Venezuela, and even on occasion up to 1600 m. Very much an edge species, occupying rank, grassy borders of primary and secondary forest, swampy thickets at water’s edge along forested rivers, and large, regenerating light-gaps within terra firme forest. In upper R Negro-R Orinoco region occupies stunted savanna woodland growing on white-sand soils, primarily in humid, shrubby forest borders and swampy, low-lying thickets of broad-leaved herbaceous plants in forest interior. In foothills in Peru found along forest edge on ridgetops; in lowlands of SE Peru and N Bolivia commonly in “zabolo” riverbank forest characterized by such trees as Cecropia, Ochroma and Erythrina, with undergrowth of Gynerium cane, Guadua bamboo and broad-leaved plants (including Heliconia and Costus), but also occurs along road edges and in second growth.

None recorded; presumed resident.

Feeds on various insects and spiders, probably also on other arthropods; frog fed to nestling. Recorded prey in Brazil include termites (Termitidae), beetles (Elateridae, Curculionidae), hemipterans (Pentatomidae), craneflies (Tipulidae), orthopteran egg cases; in Surinam beetles, katydids (Tettigoniidae), larvae of owlflies (Neuroptera: Ascalaphidae), spiders. Closely associated pair-members, individuals, or family groups forage mostly 0–1 m above ground, occasionally to 3 m, apart from mixed-species flocks; pairs and family groups are typically very vocal when foraging, keeping in close contact by frequent loud calls. Somewhat terrestrial, progressing by short hops on ground, and frequently jumping up to low perches to scan before dropping back down, but sometimes moves through an area on vertical stem perches a few centimetres off ground; generally sticks to dense (often herbaceous/grassy) cover, and tends to flutter quickly across even small open gaps; constantly lowers tail slowly to 45 degrees or more below level of body, then flicks it rapidly upwards to as much as 20 degrees above horizontal, also habitually flicks both wings shallowly. Perch-gleans most prey from tops and bottoms of live leaves, branches, stems, vines, grass blades or the ground by reaching up, out or down with quick stabs of the bill, or by short horizontal lunges; makes short, fluttering jump-gleans to take prey from underside of overhanging vegetation; probes noisily in leaf litter with its bill, but not seen to toss leaves. Rarely attends swarms of army ants.

Loudsong a short series (e.g. 9 notes, 1·6 seconds) of downslurred notes at about same pitch, those in first half of song lengthen, slow down and become more intense, followed by notes having similar length and intensity and delivered at even pace. Calls include sharply downslurred (e.g. dropping from 7·5 to 2·5 kHz) note and mixture of abrupt “chit” notes given in short bursts mixed with moderately long (e.g. 0·3 seconds), flat whistles.

Nest found in Apr in French Guiana (details previously unpublished); adult carrying nest material in Jul in S Peru; fledgling seen in Dec in Brazil (Mato Grosso). Nest a cup constructed from dead leaves of sedges and some broader leaves, lined with Marasmius fibres, built c. 20 cm over water in large clump of sedge (periphery of clump and the surrounding sedges and trees flooded); contained only 1 nestling, fed by both parents with insects and one small frog, fledged the day after nest discovered. Eggs from Bolivia said to be like those of Myrmoderus squamosus but darker and more heavily marked.

Not globally threatened. Fairly common throughout its extensive range. Numerous formally protected areas exist within regions occupied by this species, and in virtually every country in which it occurs. Its ability to occupy a variety of secondary and edge habitats renders it less vulnerable to disturbance than are most other thamnophilids.