Predicted Antwren Herpsilochmus praedictus Scientific name definitions

The unusual English and scientific names of Predicted Antwren stem from the discovery of this species: field ornithologists had predicted that a Herpsilochmus antwren "ought to occur" in southwestern Amazonia, before this species was discovered in life. This species now is known to be widespread, reported from a large number of sites between the Purus and Madeira rivers in Brazil, where it primarily occupies relatively low stature forest on sandy soils near the edge of savannas, but its western and northern geographical limits have not yet been established. In appearance, Predicted Antwren resembles may other species in the genus: the upperparts are primarily gray, with a black crown, tail, and wings. It also has a conspicuous whitish supercilium, prominent white wingbars, and pale gray underparts. The sexes are similar, but the female has an orangish forecrown, and the crown has short white streaks. Predicted Antwren is most similar to its sister species, Aripuana Antwren (H. stotzi), which occurs on the east side of the Madeira River. Fortunately, these two species are readily distinguished by the pace and structure of the song. Little is known about the natural history of Predicted Antwren, but, like other species of Herpsilochmus, it is insectivorous, and pairs regularly join mixed species flocks foraging in the canopy.

11–12 cm; 11·2 g. Male  is very similar to many congenerics, especially the recently described H. stotzi from which it appears to differ morphologically only in showing slightly more black on upperparts. Adult female is also generally very close to those of several other Herpsilochmus, especially H. stotzi, but differs from latter in having a more uniform and darker rusty forehead and lores (whereas the loral region is paler than the forehead in H. stotzi), and also has longer and broader whitish coronal streaks, which in contrast in H. stotzi are finer, smaller and more numerous, giving the crown a speckled, rather than heavily streaked, appearance.

S of Amazon from R Juruá to R Madeira, in S Amazonas, Brazil.

Middle and upper strata of tall humid evergreen forest on terra firme (weathered clay soils), as well as low-stature forest on sandy soils (campinarana), which is perhaps its favoured habitat, and seasonally-flooded, low-canopy igapó along small, black-water rivers, but not in floodplain várzea along major rivers such as the Madeira, Purus and Juruá. Research indicates that this species is rare in terra firme forest in regions where campinas are few, and its presence in the former habitat seems linked to the presence of palms such as Lepidocaryum tenue and Oenocarpus bataua, while igapó where this species occurs are usually characterized by unusual woody plants like Qualea or Ruitzerania (Vochysiaceae), Aldinia (Fabaceae) and grass-like ferns of the genus Actinostachys (Schizeaceae). Lowlands.

Diet unknown beyond arthropods (based on stomach contents). Like other Herpsilochmus, often accompanies mixed-species foraging flocks of insectivores, moving through highest foliage, ranging from 5 m to > 30 m above the ground, often near the tips of tree crowns. Most aspects of foraging ecology probably broadly similar to those of H. atricapillus (which see).

Loudsong a soft, purring, rolling trill, lasting c. 1·5–2 seconds, which initially rises in frequency (from c. 1·5 kHz to 2·2–2·4 kHz) before declining again to a frequency similar to that on which it started; given by both sexes, usually alternating slightly, so that there are never perfectly synchronized, and possibly achieving slightly different peak frequencies. The loudsong is similar to those of several congenerics, especially the also recently described H. stotzi as well as H. dorsimaculatus, but readily distinguished (especially when reproduced spectrographically) by the large number of notes (48–60 versus 27–34 in both H. stotzi and H. dorsimaculatus over same duration) and fast, slightly decelerating pace, with inter-note intervals increasing towards the end; both of the other two mentioned species sound slower and higher-pitched compared to H. praedictus, with H. stotzi decelerating even more dramatically towards the terminus, whereas the loudsong of H. dorsimaculatus actually increases in tempo prior to its conclusion. Two distinctive calls are known. A dull “pwip” is similar to analogous calls given by H. stotzi and H. dorsimaculatus, in lasting c. 0·1 second, but is characterized by a distinctive note shape in each: in the present species like that of an inverted U, whereas in H. stotzi it has a conspicuous double inflection followed by a steady rise, thus sounding bisyllabic, and in H. dorsimaculatus the note shape is somewhat intermediate, the sound is lowest in pitch, and this call is rarely heard. More frequently heard from the present species is a short, sharply-descending “chew”, given either singly or in series of 2–3 notes, occasionally more, to which a virtually identical analogous vocalization exists in H. stotzi, but none in H. dorsimaculatus.

Not globally threatened (Least Concern). Reasonably common and widespread, with a comparatively wide habitat tolerance. Confined to the area between the R Juruá and R Madeira, S of the Amazon, in Brazil. This region has been subject to comparatively little deforestation and other anthropogenic impacts to date, although these are increasing within the species’ core range, despite the recent creation of a number of not yet fully implemented conservation units, which if effectively enshrined could secure its future. Most records to date come from the Madeira-Purus interfluvium (where it is known from dozens of sites), with just two localities known from further W (in the Purus-Juruá interfluve), in the upper Urucu basin and on the E bank of the middle Juruá, although the possibility that it ranges even closer to Peru should be considered.