Appearance

Black-capped Pygmy Tyrant is a tiny flycatcher with a blackish cap, olive green upperparts, a very short tail, and white spectacles (Stiles and Skutch 1989). The underparts are pale gray or whitish. Its total length is only around 6.5 cm, with the tail less than half as long as the wing (Wetmore 1972).

Black-capped Pygmy-Tyrant is very similar to the closely related Short-tailed Pygmy Tyrant (Myiornis ecuadatus) (Ridgely and Gwynne 1989, Stiles and Skutch 1989), and the two sometimes are considered to be conspecific. Their distributions are completely allopatric, however, as Short-tailed occurs east of the Andes in the Amazon Basin. Short-tailed Pygmy-Tyrant also differs in plumage: it has a paler gray crown, is whiter on the belly, and has less prominent white "spectacles" above bill and around the eyes (Wetmore 1972).

Black-capped Pygmy Tyrant is the smallest Central American passerine (Ridgely and Gwynne 1989) and one of the smallest passerines on Earth. Its smaller size and pale gray, not yellow, underparts easily distinguish it from Black-headed Tody-Flycatcher (Todirostrum nigriceps) (Ridgely and Gwynne 1989).

The following description is based on Wetmore (1972); see also Ridgway (1907):

Adult male: Crown black, becoming slate gray posteriorly. Nape and sides of head slate gray. Back, scapulars, rump, and uppertail coverts, and lesser wing coverts bright olive green. Remiges and rectrices slate black, feathers edged with olive green to yellowish, broader and yellower on the inner secondaries. Greater and middle wing coverts slate black, tipped with olive green. Lores white, with a black spot adjacent to the eye; white of lores continuous with a white eyering. Throat and center of breast white, sides of breast pale gray. Tibial feathers dusky, tipped with white. Belly, flanks, and undertail coverts pale yellow.

Adult female: Similar to adult male, but crown duller: dull black on the forecrown to dusky slate posteriorly.

Juvenile: Similar to adult female.

Undescribed.

Iris: dark brown, brown

Bill: black, base of gonys and extreme tip of mandible white

Tarsi and toes: pale brown or pink to orangish

Bare parts color data from Wetmore (1972), Robbins et al. (1985), and Stiles and Skutch (1989).

Total length: 6-7 cm (Wetmore 1972), 6.5 cm (Stiles and Skutch 1989, Ridgely and Greenfield 2001b)

Linear measurements (from Wetmore 1972):

male (n = 10)

wing length: mean 35.7 mm (range 34.5-37.7 mm)

tail length: mean 14.3 mm (range 12.7-15.7 mm)

bill length (culmen from base): mean 11.6 mm (range 10.5-12.3 mm)

tarsus length: mean 12.8 mm (range 12.1-13.5 mm)

female (n = 5)

wing length: mean 34.4 mm (range 33.5-35.2 mm)

tail length: mean 14.0 mm (range 13.8-14.3 mm)

bill length (culmen from base): mean 11.3 mm (range 10.0-11.6 mm)

tarsus length: mean 12.9 mm (range 12.5-13.7 mm)

Mass: male, 6 g (n = 1; Robbins et al. 1985); female, 5.5 g (n = 2, range 5.5-5.5 g; Robbins et al. 1985)