Fiery-throated Hummingbird vs Green-breasted Mountain-gem

In short

The most reliable field mark to separate Fiery-throated Hummingbird from Green-breasted Mountain-gem is the Fiery-throated’s brilliant, fiery copper-orange throat center, which flashes in good light, surrounded by golden green and a violet-blue breast patch—features never shown by the Green-breasted. In contrast, adult male Green-breasted Mountain-gems are deep metallic grass green below, lacking any fiery or violet tones, and females have a buffy throat and grayish underparts. Both species are similar in size and structure, but the Fiery-throated’s crown is a striking royal blue, while the Green-breasted has a more uniform green upperpart with bronze on the rump and a distinctive white post-ocular stripe. Juvenile and immature birds can be trickier, but the throat and underpart colors remain the most useful clues. Range is also a strong context clue: Fiery-throated occurs only in Costa Rica and western Panama, while Green-breasted is found in Honduras and Nicaragua.

Identification tips

1. Fiery throat center (Fiery-throated only): Look for a brilliant coppery-orange patch in the center of the throat, especially when the bird turns into the light. This is diagnostic for Fiery-throated and never shown by Green-breasted, in any age or sex.
2. Violet-blue breast patch (Fiery-throated): A distinct violet-blue patch on the center of the breast is unique to Fiery-throated; Green-breasted males are green-breasted with no violet.
3. Crown color: Fiery-throated has a royal blue crown, contrasting with its black face and nape. Green-breasted has a more uniform metallic green crown and upperparts, sometimes with bronze on the rump.
4. Face pattern: Fiery-throated shows a small white spot behind the eye. Green-breasted has a bold white stripe curving behind the eye and a thin white stripe below the green cheek, creating a more pronounced facial pattern.
5. Bill color: Fiery-throated’s bill is mostly black with a pink base to the lower mandible; Green-breasted’s bill is all black and straight.
6. Tail pattern: Fiery-throated’s tail is blue-black throughout. Green-breasted’s tail is grayish black centrally, with outer feathers pale gray to white and broad white edges (especially in females), and a dusky bar near the tip.
7. Underpart color (males): Fiery-throated males have a multi-colored throat and breast (copper, gold, violet, green), while Green-breasted males are metallic grass green below, with white or grayish feather margins and a white vent.
8. Underpart color (females): Green-breasted females have a buff chin and throat and grayish white underparts with green on the breast sides; Fiery-throated females resemble males and never show a buff throat.
9. Juvenile/immature marks: Green-breasted juveniles show dark green mottling on the throat and buffy to cinnamon tips on upperpart feathers. Fiery-throated juveniles are not described as having these features.
10. White leg tufts and vent (Green-breasted): Green-breasted males have white leg tufts and a white vent area, which Fiery-throated lacks.
11. Uppertail coverts: Fiery-throated’s uppertail coverts are blue-green to blue; Green-breasted has black uppertail coverts.
12. Range: If seen in Costa Rica or western Panama, Fiery-throated is expected; in Honduras or Nicaragua, Green-breasted is the likely species. Range does not overlap.
13. Aggression: Fiery-throated is notably aggressive and dominant at feeders and flower patches, which may help in mixed-species situations.
14. Habitat elevation: Fiery-throated is mostly found above 1,600 m, often up to 3,200 m; Green-breasted’s elevation is less well documented but is also a highland species.
15. Vocalization: Fiery-throated gives a repeated nasal 'kek...kek...'; no comparable call is described for Green-breasted, so use with caution.

Size

Both species are very close in size, with Fiery-throated Hummingbird at 10.5–11 cm in length and Green-breasted Mountain-gem at 10–11 cm. The Green-breasted’s average body mass (5.8 g) falls within the Fiery-throated’s reported range for both sexes. Structurally, both have medium-length, mostly straight black bills, though the Fiery-throated’s bill base is pinkish below, while the Green-breasted’s is all black. Size alone is not a reliable separator in the field.

Plumage

• Juvenile/immature birds: Green-breasted Mountain-gem juveniles show dark green mottling on the throat and buffy to cinnamon tips on upperpart feathers, transitioning to adult throat and tail colors as they mature. Fiery-throated Hummingbird juveniles are not described in detail, but no mention of similar mottling or cinnamon-tipped feathers.

• Adult males: Fiery-throated Hummingbird males have a glittering royal blue crown, black face and nape, bright metallic green back, blue-black tail, and a spectacular fiery coppery-orange throat center bordered by golden green, with a violet-blue breast patch and bright green to blue-green underparts. Green-breasted Mountain-gem males are deep metallic grass green above and below, with some bronze on the rump, black uppertail coverts, and a white post-ocular stripe; their underparts are green with white or grayish feather margins, and their lower belly and vent are white.

• Adult females: Fiery-throated females are similar to males. Green-breasted females have a buff chin and throat, grayish white underparts with metallic green on the breast sides, and a more patterned tail with white or grayish white outer feathers and a dusky bar near the end. Some females show a green sheen on the upperside of central tail feathers.

• Tail: Fiery-throated has a blue-black tail; Green-breasted’s tail is grayish black centrally, with outer feathers pale gray to white and broad white edges, especially in females.

• Face: Fiery-throated has a small white spot behind the eye; Green-breasted has a bold white stripe curving behind the eye and a thin white stripe below the green cheek.

Behaviour

Fiery-throated Hummingbird is notably aggressive and dominant over other hummingbirds, often defending feeding territories, especially during and after the breeding season. Both sexes may defend territories post-breeding. Green-breasted Mountain-gem’s foraging behavior is less documented, but it feeds on nectar and small arthropods. No mention of similar aggression or territoriality. Both species feed in forested habitats, but Fiery-throated is more often described as active in the canopy and at forest edges.

Habitat

Fiery-throated Hummingbird is restricted to highland forests of Costa Rica and western Panama, favoring montane forest, cloudforest, elfin forest, and sometimes open areas like páramo edges or pastures with trees, mainly at elevations from 1,600–3,200 m depending on latitude. Green-breasted Mountain-gem is found in Honduras and Nicaragua, also in forested highlands, but with no further habitat details provided. If seen outside their respective ranges, misidentification is unlikely; range is a strong clue.

Voice

Fiery-throated Hummingbird gives a repeated nasal, squeaky 'kek...kek...' and a complex fast liquid call, but does not have a true song. No vocalization details are provided for Green-breasted Mountain-gem, so voice is not a reliable separator.