A medium-sized screech-owl that has short ear tufts and yellow irides. The black rims of the facial disks are prominent, as are the whitish "eyebrow" lines. The underparts generally are pale, but with many short, black streaks, with numerous narrower cross bars (creating a "herringbone" pattern). Tropical Screech-Owls have different morphs; the most frequent is the gray-brown morph, but brown and rufous morphs also occur.
Across its wide geographic range, the Tropical Screech-Owl overlaps with many other species. In Costa Rica, it is distinguished from the Pacific Screech-Owl (Megascops cooperi) by the more prominent black rims to the facial disks and by the heavier streaking below. The Bare-shanked Screech-Owl (Megascops clarkii) of the highlands of Panama and Colombia has cinnamon facial disks that lack the black rims, and is browner below with prominent white spotting.
In Peru, not known to overlap geographically with similar Koepcke's Screech-Owl (Megascops koepckeae) or Peruvian Screech-Owl (Megascops roboratus). Peruvian has a narrow white band across the rear of the crown, lacking in Tropical, and the inner webs of the primaries are dark with little or no mottling (both webs are mottled in Tropical). Koepcke's is very similar to Tropical, but has more coarsely patterned underparts.
Black-capped (Megascops atricapillus) and Long-tufted (Megascops sanctaecatarinae) screech-owls occur sympatrically with the Tropical Screech-Owl in southeastern South America. Black-capped Screech-Owl is slightly larger than the Tropical Screech-Owl and has a dark, nearly uniform crown, a whitish fringe surrounding the hindneck, longer ear-tufts, and less herringbone-like patterns below. The Long-tufted Screech-Owl has longer ear-tufts and is much larger and heavier. Montane Forest Screech-Owls (Megascops hoyi) occupy montane cloud forests on the eastern slopes of the Andes of Bolivia and Argentina, where they may overlap locally with the Tropical Screech Owl. The Montane Forest Screech-Owl have a whitish fringe around the hindneck, and a less distinct black rim to the facial disk. All species are best differentiated by their vocalizations.
The following description is of nominate choliba, and is based on König and Weick (2008); see also Geographic variation.
Adult: Sexes similar, but the species is polymorphic, with grayish brown, red, and brown morphs, as well as birds with intermediate plumages; the gray-brown morph is the most common.
Grayish brown morph: The facial disk is pale grayish brown, somewhat mottled darker. Black rim bordering the facial disk is prominent. Eyebrows are whitish, and extend towards the ear tufts. Upperparts grayish brown, with dark streaks and mottling. The crown is as the back, with blackish shaft-streaks; there is no white rim to the rear crown. Scapulars have whitish or pale ochre outer webs (with dark borders), forming a row of whitish or yellowish spots. Remiges are barred light and dark. Rectrices The tail feathers are mottled and indistinctly barred. The underparts are whitish gray; feathers have a herringbone pattern with a dark central streak and 4-5 thinner, lateral bars. The tarsi are feathered to the base of the toes.
Red and brown morphs: The red morph's general coloration is rusty or cinnamon-buffish; the brown morph has predominating brownish colors.
Juvenile: Downy chicks are whitish. Mesoptile feathering of half-grown young is distinctly barred.
Little information. Willard et al. (1991) reported body molt on single specimens of duidae from early February and mid-March in southern Venezuela.
Bare part colors from Wetmore (1968), Belton (1984), Willard et al. (1991):
Iris: Clear yellow, golden yellow, light yellow, orange-yellow.
Bill: Top of cere and tip of maxilla dull honey yellow; rest of bill and the sides of the cere are dull greenish gray.
Tarsi and toes: Brownish neutral gray, grayish flesh, gray.
Total length: 21 cm (Hilty 2003), 23 cm (Hilty and Brown 1986), 21-23 cm (Schulenberg et al. 2007)
Wing 148-180 mm; tail 86-104 mm;
Weight 97-160 g.
All measurements from König (1999) and del Hoyo (1999).
See also geographic variation.