Appearance

This large and rather stout hummingbird is predominantly green in all plumages and has a straight bill and forked tail; males have brilliant green to blue-green frontal plumage and a distinct white postocular spot (Stiles and Skutch 1989, Stiles 1999). Females have a short white malar streak and white postocular spot, with whitish underparts spotted green. Immature birds have bright buff throats (Stiles and Skutch 1989, Stiles 1999).

In its Central American range, the male is rather distinctive, while the female's white malar stripe helps to distinguish it from other species with greenish-spotted underparts (Garrigues and Dean 2007), although no other highland hummingbirds in this region are as boldly spangled below (Ridgely and Gwynne 1989). Juvenile Green-crowned Brilliants may be responsible for some reports of Fiery-throated Hummingbird (Panterpe insignis) below its normal elevation range (Garrigues and Dean 2007).

In South America, male Green-crowned Brilliants are told from male Violet-fronted Brilliants (H. leadbeateri) by their glittering green, not violet, crown (Hilty and Brown 1986); females of these two species are very similar, but those of the Green-crowned Brilliant have less deeply forked tails (see Restall et al. 2006). The female Empress Brilliant (H. imperatrix) is very similar, but, compared to the Green-crowned Brilliant, the green-spotted belly has a cinnamon wash, it has only a faint white malar streak, green crissum and no white spots on the tail feathers (see Ridgely and Greenfield 2001).

A large hummingbird with medium-length straight bill.

Adult, male: The male has glittering green to blue-green forehead, crown, lores, throat, and breast, with a small metallic violet-blue patch on the foreneck and white postocular spot (Stiles and Skutch 1989, Stiles 1999). The rest of the upperparts and belly are bronzy-green. The crissum and thighs are white. The deeply-forked tail is blue-black, but the central tail feathers are bronzy in subspecies jacula and glossed green in subspecies jamesoni (Stiles 1999).

Adult, female: Differs in lacking the glittering areas on the head and underparts and has a short white malar streak, as well as a white postocular spot (Stiles 1999). The underparts are whitish and heavily spotted with green, with spots becoming contiguous on the flanks (Stiles and Skutch 1989, Stiles 1999). The shallowly-forked tail is black with the outer tail feathers tipped white.

Immature: Males have a shorter, less deeply-forked tail, and are dull bronzy-green on the crown and underparts, with bright buff on the chin and malar area, and sometimes the entire throat (Stiles 1999). Immature females also have bright buff throat, and duller green spotting below.

Hummingbirds have a single complete annual molt, which starts soon after the breeding season (Schuchmann 1999). Feather replacement is slow and takes several months.

Stiles (1995) noted molt patterns in a sample of 26 Green-crowned Brilliants trapped in Costa Rica. Most of these individuals appeared to molt their primaries from the innermost to the outermost, with the outermost usually molting in the sequence 8-10-9. This strategy is apparently used because the outermost two primaries are vital for maintaining the aerodynamic stability of the wing tip during hovering flight (Stiles 1995, and references therein). The molt sequence of secondaries and rectrices is more variable (Stiles 1995). Secondary molt begins during primary molt, with molt of the two tracts completed roughly synchronously. The timing of rectrix molt, however, is more variable. The molt of wing and tail coverts appears to start when primaries 2-4 are in molt and is completed when primaries 8-9 are in molt. Body molt proceeds throughout primary molt, with that of the brilliant frontal plumage in males, especially the forehead and chin, delayed (relative to primary molt) in comparison to that of other body plumage (Stiles 1995). This delay may be an adaptation that ensures birds enter the next breeding season in optimal plumage condition (Stiles 1995, and references therein; Schuchmann 1999).

Its black bill is straight and of medium-length for a hummingbird; the feet are described as dusky in coloration (Stiles and Skutch 1989).

The total body length is given as 12-13 cm in males and 10.5-12 cm in females (Stiles 1999).

Wetmore (1968) provided biometric data (mean, range) for the males and females of two subspecies (see Geographic Variation):

Males - H. jacula jacula (n=10, Darién, Panama and Colombia): Wing length = 74.4 mm, 72.3-77.6 mm; tail length = 49.8 mm, 47.1-52.5 mm; culmen from base = 25.1 mm, 23.7-26.1 mm. H. jacula henryi (n=10, Panama): Wing length = 75.5 mm, 72.7-77.7 mm; tail length = 52.6 mm, 50.2-54.1 mm; culmen from base = 24.5 mm, 23.7-25.7 mm.

Females - H. jacula jacula (n=9, Darién, Panama and Colombia): Wing length = 66.8 mm, 65.1-67.9 mm; tail length = 40.5 mm, 38.5-43.1 mm; culmen from base = 25.9 mm, 24.7-27.2 mm. H. jacula henryi (n=9, Panama): Wing length = 67.2 mm, 64.8-69.8 mm; tail length = 41.3 mm, 39.1-43.4 mm; culmen from base = 25.3 mm, 24.1-26.7 mm.

Mean bill length (± 1 standard deviation) for a sample of 9 individuals trapped in southern Costa Rica was 21±0.9 mm (Borgella et al. 2001). Feinsinger et al. (1988) recorded longer bill lengths in Costa Rica, with means of 27.6 mm in 8 males and 28.8 mm in 16 females.

Mass: 7.39 g (n=1, female; Hartman 1954)