Definitive-plumage males have deep, coal black body plumage; an upright, bright yellow crown that extends forward beyond the nares; short black "horns"; scaly, bristly, brightly colored feathers on the nape, which are orange brown (west slope) or red (east slope); and a yellow throat patch. In flight, definitive males also reveal bright yellow patches on the remiges and the outer rectrices.
Females and hatch-year males are drabber, with olive green body plumage, but can show a yellow throat and breast accents (in females) and yellow underwing patches (in both sexes). Pre-definitive males begin to show increasingly upright yellow feathers on the crown, green "horns", and the beginnings of a waxy nape.
Both sexes have the large heads and plump bodies found in most manakins, but their relatively long tails give them a slender appearance.
Definitive males of this species are unmistakable with coal black plumage and bright yellow crown, throat, and wing patches.
Female and hatch-year male Golden-winged Manakin may resemble some other green-plumaged manakins, such as female and young Red-capped Manakin (Ceratopipra mentalis) or White-bearded Manakin (Manacus manacus). Unlike these other species, however, both sexes of Golden-winged Manakins have a pale bill and yellow underwings, although this may be apparent only in the hand. Females can be further distinguished from other manakin species by the yellowish throat and long tail (Kirwan and Green 2012). Both of these species also typically occur at lower elevations than does Golden-winged Manakin. Both sexes of Green Manakin (Cryptopipo holochlora) are green, but can distinguished by their dark bill and gray tarsi; the tarsi and toes of Golden-winged Manakin are purplish red. The female Jet Manakin (Chloropipo unicolor) is a duller, more olive green, and also has a dark bill and tarsi; additionally, the underwing coverts are white, not yellow.
From a distance, green-plumaged Golden-winged Manakin also may recall some small green songbirds such as young Orange-bellied Euphonia (Euphonia xanthogaster). Unlike euphonias and similar passerines, however, Golden-winged Manakin has paler, pinkish or purplish red tarsi, and the round body shape characteristic of manakins.
The following description is based on Prum and Johnson (1987); see also Geographic Variation:
"Adult male Masius are velvety black with patches of bright golden-yellow (Spectrum Yellow, Smithe 1975) on the tail, wing linings, flight feathers, throat, and forecrown, and a patch of orange, red, or brown on the hindcrown …. Primary and secondary flight feathers and the outer tail feathers are entirely yellow with thin black stripes along the leading edge of their outer vanes. These black edges often conceal the yellow wing and tail patches when the male is perched. The yellow forecrown consists of thin, plush feathers that curve forward over the culmen and which may be erected posteriorly to produce a slight crest at the top of the head. The posterior half of the crown consists of orange, red, or brown barbless feathers that are thickened and blunt in shape, and smooth and shiny in texture (similar to specialized feathers of Bombycilla [waxwings] and Chlorochrysa [tanagers, e.g., Multicolored Tanager Chlorochrysa nitidissima]). The posterior portion of the crown cannot be erected. Laterally bordering the forecrown are two short black plumes that can be erected to form 'horns' on either side of the head. Female Masius are generally olive-green in plumage with yellow-olive on the throat, belly, and wing linings.... Immature male Masius first resemble females and then molt into adult male plumage…. Both sexes have dark brown irises, purplish-pink legs, and pinkish-gray bills".
The molt sequence of females has yet to be described.
Males develop definitive plumage over multiple years, although the precise timing is unknown. In general, males pass through four distinct plumage stages (Meyer de Schauensee 1945, R. O. Prum, personal communication.):
Stage 1: "Female-like" green/olive, with only a few yellow accents on the breast
Stage 2: Green with a yellow forecrown with black tips on the posterior end of the crown
Stage 3: Yellow forecrown, wings, and tail, a black body that retains large green patches, and flattening occipital crest feathers that shift from dark brown to red or orange.
Stage 4: Definitive male plumage
Based on testis size, males reach sexual maturity during Stage 1 plumage (R. O. Prum, unpublished data).
Individual plasticity of plumage maturation and the factors (such as social environment) that drive such plasticity are unclear. At El Placer, Ecuador in 1985, an individual was in an advanced Stage 3 plumage with an entirely black body except for immature-like olive green upper wing coverts. When the same individual was netted at the site 15 months later, it retained the same, distinctive plumage stage (R. O. Prum, unpublished data).
Iris: dark brown
Bill: pale pink to pale gray
Tarsi and toes: brownish pink or purplish pink to almost purple, with slightly paler orange or tan skin under the toes
Total length: 10.9 cm (Hilty and Brown 1986), 11 cm (Ridgely and Greenfield 2001a), 12.6 cm (Carriker 1934),
Linear measurements: (from Carriker 1934):
wing length: male, 62 mm (n = 3); female, 62 mm (n = 1) (Carriker 1934)
tail length: male, 45 mm (n = 3); female, 44 mm (n = 1) (Carriker 1934); male, 37.3 mm (range 35.0-39.6 mm (n = 2) (live birds, not dried specimens; from Milpe Bird Sanctuary, Ecuador; David McDonald data from 2013-2017)
male: mean 10.2 g (range 9.0-12.5 g, n = 8) (Prum and Johnson 1987); mean 11.2 g (range 9.5-13.5 g, n = 29) (from Milpe Bird Sanctuary; David McDonald data from 2013-2017)
female: 13.5 g (n = 1) (Prum and Johnson 1987); mean 12.1 g (range 11-13 g, n = 11) (from Milpe Bird Sanctuary, Ecuador; David McDonald data from 2013-2017)