Tit-tyrants (Anairetes) are small, active tyrant flycatchers with a short, slender bill and a thin, wispy crest. The back and rump of Tufted Tit-Tyrant are dull brown or gray, but the underparts are boldly streaked with black, against a background of white (throat and breast) or yellow (belly). The wings are plain, or have narrow white tips to the wing coverts, forming narrow wing bars. Two of the most distinctive features of Tufted Tit-Tyrant are the black crest on the forecrown, and the stark yellow or whitish irides.
In the northern portion of its range, in Colombia and Ecuador, and again in the south, in most of Chile, Tufted Tit-Tyrant is unlikely to be confused with any other species: the combination of very small size, wispy black crest, and prominent streaking on the breast and belly are distinctive. From northern Peru south to southern Argentina, however, Tufted is broadly sympatric with Yellow-billed Tit-Tyrant (Anairetes flavirostris). Yellow-billed is very similar to Tufted, but differs in its dark iris, prominent yellow base to the mandible, broader pale wingbars, and broader black streaking on the underparts. Yellow-billed Tit-Tyrant also prefers drier habitats than the humid scrub occupied by Tufted Tit-Tyrant.
Tufted Tit-Tyrant also is very similar to Juan Fernandez Tit-Tyrant (Anairetes fernandezianus). The species are completely allopatric, however, as Juan Fernandez is endemic to the Juan Fernandez Archipelago, west of Chile, where Tufted does not occur. Juan Fernandez Tit-Tyrant is larger than Tufted, with a longer crest and a whiter belly, and its underparts are more heavily streaked.
Yhe following description is based on Fjeldså and Krabbe (1990) and Fitzpatrick (2004), and refers to nominate parulus; see also Geographic Variation:
Adult: Sexes similar. Crown dark gray to black; feathers on central crown narrow, elongated, and recurving, forming a thin crest that tips forward; forecrown variably streaked with white. Small white concealed median crown spot, sometimes lacking. Back and rump dark gray. Rectrices dusky, narrowly tipped with whitish; outer web of outermost pair also whitish. Wings blackish, wing coverts narrowly tipped with white, forming two narrow, somewhat indistinct wingbars. Remiges narrowly edged with white to pale yellow, these margins broader on innermost remiges. Lores black, with a white supraloral spot; also a white postocular streak. The sides of the head, the throat, and the breast are white, narrowly streaked with dark gray to black. Lower breast yellowish, belly and undertail coverts medium yellow.
Juvenile: Similar to adult, but duller, with shorter crest, no white in crown, and the wingbars are washed with buffy.
Iris: pale yellow, creamy white, grayish white, white
Tarsi and toes: black
Bare parts color data from Pässler (1922), Johnson (1967), Fjeldså and Krabbe (1990), and Fitzpatrick (2004).
Total length: 9.5 cm (Fjeldså and Krabbe 1990), 11 cm (Ridgely and Greenfield 2001b), 11-12 cm (Jaramillo 2003)
Linear measurements (from Johnson 1967; nominate parulus, n = ?):
wing length, mean 47.7 mm ± 0.31 mm
tail length, mean 47.8 mm ± 0.52 mm
bill length, mean 8.4 mm ± 0.19 mm
Mass: mean 6.2 g ± 0.5 g (n = 113, sexes combined, nominate parulus, Chile; Dunning 2008)