Short-tailed Antthrush, like other species of Chamaeza, is a stout, forward-leaning ground antbird. The upperparts of Short-tailed Antthrush are warm brown above with a short whitish or buff supercilium. The underparts are off white or buffy below, streaked or scalloped with black on the breast and flanks. The tail is relatively short and is warm brown, with a black subterminal band and a narrow whitish tip.
Along the Andean foothills, the distribution of Short-tailed Antthrush closely approaches that of Striated Antthrush (Chamaeza nobilis) of Amazonia. These two species are separated elevationally, however, and rarely if ever are syntopic. Additionally, Striated Antthrush is larger than Short-tailed, Striated has more rufescent upperparts and has much whiter underparts, and the songs of the two species differ markedly.
Short-tailed Antthrush is closely similar to several other species of montane antthrushes, all of which are more geographically restricted, and all of which are more easily distinguished by their different songs. Schwartz's Antthrush (Chamaeza turdina) overlaps with Short-tailed Antthrush in the coastal cordilleras of northern Venezuela; Schwartz's Antthrush also occurs locally in the Colombian Andes, but is not known to overlap geographically with Short-tailed in that region. In Venezuela, Schwartz's Antthrush usually occurs at higher elevations (1500-2100 m) than does Short-tailed (ca 1100-1500 m), although the elevational ranges of the two species show some overlap. In the hand, or at very close range, Schwartz's also differs by being slightly smaller, the tail is entirely brown, the underparts are more scalloped (less streaked) and the breast is more heavily marked, and Schwartz's has a slightly smaller bill than does Short-tailed.
Short-tailed Antthrush also overlaps with two additional species in southeastern South America: Rufous-tailed Antthrush (Chamaeza ruficauda) and Such's Antthrush (Chamaeza meruloides). Rufous-tailed Antthrush is slightly smaller than Short-tailed, with a shorter bill, and the tail is uniformly brown (lacking the black subterminal band and white tips of Short-tailed). Rufous-tailed Antthrush also occurs at higher elevations than Short-tailed, and its song, a short rising trill, is very different. Such's Antthrush is particularly similar to Short-tailed Antthrush, and, although Such's also usually occurs at higher elevations, the elevational distributions of the two species may overlap. Short-tailed Antthrush has a small black mark on the forecrown, which is lacking on Such's. Such's Antthrush also has a slightly smaller and darker bill. The song of Such's Antthrush is a long series of notes that increases in volume, but that does not end with the diagnostic terminal grunts of the song of Short-tailed Antthrush.
The following description is based on Krabbe and Schulenberg (2003); see also Geographic Variation:
Adult: Sexes similar. Crown rufescent brown or brown; black spot on forecrown directly above the bill. Upperparts (back, wings and uppertail coverts) olive brown. Rectrices brown, with a black subterminal band and narrow buff or whitish tips that are broader and more conspicuous on the under surface. Lores white. White postocular streak and whitish patch on sides of neck, below the auriculars. Throat white. There is a rich buff wash across the upper breast and on the crissume. Breast and flanks broadly streaked black; center of belly unmarked or only lightly marked, but there are a few scattered black bars or spots on the crissum.
Iris: dark brown
Bill: black, mandible paler near base
Tarsi and toes: brown, brownish gray
Total length: 19 cm (Hilty and Brown 1986) 19-20 cm (Krabbe and Schulenberg 2003, Ridgely and Tudor 2009), 19.5 cm (Chubb 1921, fulvescens), 20 cm (van Perlo 2009), 20.3 cm (Hilty 2003), 20.9-21 cm (Berla 1944, campanisona), 21.1 cm (Meyer de Schauensee 1970), 21.6 cm (Snyder 1966, fulvescens), 22-23.5 cm (Belton 1985, campanisona), 22-24.5 cm (Bertoni 1901, tshororo).
Chamaeza campanisona olivacea – wing 98 mm; tail 65 mm, bill 19.5 mm (n = 1 male; Cory and Hellmayr 1924); wing 95 mm; tail 64 mm; bill 18 mm (n = 1 female; Cory and Hellmayr 1924).
Chamaeza campanisona yavii – wing 101, 105 mm; tail 60, 63 mm; culmen from base 26 mm (n = 2 males; Phelps and Phelps 1947).
Chamaeza campanisona huachamacarii – wing 101 mm; tail 64 mm; exposed culmen 20 mm; culmen from base 27 mm; tarsus 39 mm (n = 1 male; Phelps and Phelps 1951)
Chamaeza campanisona obscura – wing 97-100 (mean 99) mm; tail 57-58 (mean 57.3) mm; culmen from base 25-25.5 (mean 25.2) mm; n = 4 males; Zimmer and Phelps 1944).
Chamaeza campanisona fulvescens – wing 100 mm; tail 61 mm; culmen from base 24 mm (Phelps and Phelps 1947): wing 103 mm; tail 61 mm; exposed culmen 24 mm; tarsus 45 mm (n = 1, sex (?) ; Chubb 1921).
Chamaeza campanisona boliviana – wing 94-97 mm; tail 63-66 mm, bill 20-22 mm (n = ?; Hellmayr and Seilern 1912).
Chamaeza campanisona columbiana – wing 97.5 mm; tail 62.5-65 mm; culmen 19.75-27.5 mm; tarsus 36.5-38.5 mm (n = 2 males; von Berlepsch and Stolzmann 1896).
Chamaeza campanisona punctigula – wing 90-92 mm; tail 50-52 mm; culmen 21-23 mm; tarsus 36-38 mm (n = 3 males; Chapman 1924); wing 86 mm; tail 51 mm; culmen 20 mm; tarsus 35 mm (n = 1 female; Chapman 1924).
Chamaeza campanisona campanisona – wing 85 mm; tail 70 mm; tarsus 38 mm (Ruschi 1979).
Chamaeza campanisona tshororo – wng 97 mm, tail 72 mm (n = 1; Bertoni 1901).
Males – 93-102 g (n = 4; Belton 1985; campanisona); sex unspecified – 91.8 g (n = 1?; Willis 1992; tshororo), 93 g (n = 1; Bertoni 1901; tshororo), 89-90 g (n = ?; Willis 1992; boliviana), 64-69 g (n = ?; Willis 1992; venezuelana), 104-112 g (n = ?; Willis 1992; obscura)