Black-thighed Puffleg

Colombia

Jul 17

Black-thighed Puffleg (Eriocnemis derbyi)

Name Origin:
The genus name Eriocnemis comes from the Greek erion meaning “wool” and knemis meaning “leg armor,” referring to the distinctive fluffy leg tufts characteristic of pufflegs. The species name derbyi honors Edward Smith-Stanley, the 13th Earl of Derby, a British naturalist and collector known for his extensive contributions to zoology.

Quick Facts

🪶 Length: 8–9.5 cm (3.1–3.7 in)
⚖️ Weight: 4–5.5 g (0.14–0.19 oz)
🌎 Range: Andes of Colombia and Ecuador
🧭 Elevation: 2,500–4,000 m (8,200–13,120 ft)
🌸 Diet: Nectar and small arthropods
🏡 Habitat: Montane and elfin forest edges, shrublands, and páramo zones
🧬 Clade: Heliantheini "Brilliants" (high-Andean hummingbirds)
📊 Status: Least Concern (IUCN)

Subspecies & Distribution

(Following eBird/Clements v2024)

1. E. d. derbyi
Distribution: Western and central Andes of Colombia, from Antioquia and Cauca south to Nariño.

2. E. d. sophianna
Distribution: Andes of northern Ecuador, from Carchi south to Pichincha and Cotopaxi.

Species Overview

The Black-thighed Puffleg is a radiant high-Andean hummingbird found in the upper montane forests and páramos of Colombia and Ecuador. Its name refers to the dark, woolly feather tufts on its thighs, a defining trait of pufflegs. Seen darting among mountain flowers, it glows with deep green iridescence against the misty backdrop of the Andean slopes.

Male Description:
The male displays brilliant emerald-green plumage, black thigh puffs, and a shining turquoise-green breast. The tail is dark bronzy-green, and the bill is straight and black. In sunlight, the contrast between the gleaming plumage and the dark leg tufts is especially striking, giving this puffleg a distinctive silhouette.

Female Description:
The female is similar but has slightly duller upperparts and smaller, less conspicuous thigh tufts. Her underparts are washed with grayish green, and her tail is shorter and more rounded. She tends to forage at lower levels within the vegetation, visiting smaller clusters of flowers.

Habitat & Behavior:
This species inhabits montane and elfin forest edges, shrubby slopes, and páramo margins at elevations between 2,500 and 4,000 meters. It feeds primarily on nectar from Chuquiraga, Brachyotum, Bomarea, and Fuchsia flowers, often supplementing its diet with small insects. Males are territorial and perform short aerial chases to defend feeding areas.

Conservation Note:
Listed as Least Concern by the IUCN, the Black-thighed Puffleg remains locally common within suitable habitat. However, deforestation and fires in high-elevation shrublands pose localized threats. Conservation of cloud forest and páramo ecosystems is essential for maintaining this dazzling member of the Heliantheini, one of the emblematic hummingbird clades of the Andes.