The male Yellow-crested Tanager is somewhat two-toned, black above and tawny below. The upperparts are extensively black, other than a narrow buffy yellow crown streak and a buffy yellow or tawny yellow rump. The underparts are generally buffy yellow or tawny yellow, paler on the throat, and with a narrow black breast band, creating a "bow tie" pattern. Females are primarily yellow, greener above, and with a gray crown and sides to the head.
Male Yellow-crested Tanager is distinctive. Though it shares similar characteristics to other species of Tachyphonus in being dark above with a warm colored rump and often concealed bright crest, it easily is distinguished by the extensively tawny (not black) underparts (Ridgely and Tudor 1989). The black "bow-tie" necklace is also distinctive, though it is variable in extent, and occasionally is nearly absent. The female is more difficult to distinguish, and perhaps is most likely to be confused with female Fulvous-crested Tanager (T. surinamus), female White-shouldered Tanager (T. luctuosus), or with Gray-headed Tanager (Eucometis penicillata). All of these share similar characteristics in being olive above with a grayish head and yellowish underparts. Female Fulvous-crested Tanager is more ochre, less yellow, below, and its eye is surrounded by greenish or yellowish. Female White-shouldered Tanager is smaller, with a white throat and purer gray tones to the head. Gray-headed Tanager is larger, with a shaggy gray crest. Yellow-crested Tanager is allopatric to its sister species, Flame-crested Tanager (T. cristatus); female Flame-crested Tanager is much browner than female Yellow-crested.
Adult male: Forecrown and sides of the head black, with a semi concealed, buffy yellow streak on the center and rear of the crown; the intensity of the color of the crown streak is individually variable (Zimmer 1945, Isler and Isler 1987). Nape, sides of the neck, and upper back black. Lpwer back, rump, and uppertail coverts deep buff. Rectrices black. Wings black, but outer scapulars and bend of the wing white; this white wing patch usually is concealed, however. Throat dark yellow buff, bordered below by a narrow black breast band, broader at the sides of the breast; the extent of the breast band is individually variable, and may be obscure (Zimmer 1945, Isler and Isler 1987). Center of breast tawny, but belly, flanks, and undertail coverts yellowish buff (Hilty 2011).
Adult female: Crown and sides of the head gray. Back, wings, and tail olive. Throat whitish, shading to ochraceous buff on the breast and belly; undertail coverts ochraceous buff, tinged with cinnamon. Females vary in the depth of the color of gray on the head, and the amount of buff on the throat and undertail coverts (Zimmer 1945, Isler and Isler 1987).
Though the sexes are obviously dichromatic, they are even more dissimilar when plumage coloration is quantified under an avian vision model (Burns and Shultz 2012).
Immature: Similar to the adult female plumage, but the throat is as yellow as the breast, and the crown is olive, concolor with the back (Zimmer 1945, Isler and Isler 1987).
Plumage descriptions based on Hilty (2011), except where otherwise noted.
Tanagers that have been studied have a Complex Basic Strategy or Complex Alternative Strategy, and the preformative molt in Tachyphonus is partial in nature (Ryder and Wolf 2009). However, after formative plumage is attained, most tanagers only molt once a year (Isler and Isler 1987). This prebasic molt likely occurs after the breeding season (Isler and Isler 1987, Ryder and Wolfe 2009). Many species have been found to breed in subadult plumage (Isler and Isler 1987). Although an immature plumage is described for Yellow-crested Tanager, more specific information on molt and its timing is not available for this species. Molt has been observed in the allopatric sister species Flame-crested Tanager (Tachyphonus cristatus), with wing molt in three of four specimens captured from late February to early March (Willard et al. 1991).
Iris: dark brown
Bill: blackish, with most of the lower mandible grayish blue
Tarsi and toes: dark gray to leaden
Bare parts color data from Taczanowski (1884) and Hilty (2011).
Total length: 15-15.5 cm (Isler and Isler 1987, Sick 1993).
male, wing chord 79.5 mm; tail length 75 mm; bill length (culmen) 14.75 mm; tarsus length, 18.5 mm (n = 1; Berlepsch 1889).
male, wing length 79 mm; tail length 70 mm; bill length, 17 mm; tarsus length 19 mm (n = ?; Taczanowski 1884)
female, wing length 68-69 mm; tail length 65 mm; bill length, 16 mm; tarsus length 19 mm (n = ?; Taczanowski 1884)
Mass: mean 19 g (range 15.5-19.8 g, n = 9; Isler and Isler 1987). Additional data: 17 g (n = ?; Terborgh et al. 1990), 19 g (n = ?; Pearson 1971).