The Sooty Barbthroats (Threnetes niger) is a South American hermit (hummingbird) that is endemic to the far northeastern Brazil and the adjacent French Guiana (an overseas region of France located on the northern Atlantic coast).
They are quite common within their limited range; where they inhabit humid tropical lowland forests.
Globally, the Sooty Barbthroat is known as …
English: Sooty Barbthroat, Scientific Name: Threnetes niger; Spanish: Ermitaño Barbudo Común / Pico de Sable de Cola Blanca; Portuguese (Brazil): balança-rabo-de-garganta-preta; French: Ermite à queue blanche / Beija-flor-de-cinta ; German: Orangekehl-Schattenkolibri; Czech: kolibrík svetloocasý; Danish: Hvidhalet Skægstrube; Finnish: kaulurikolibri; Italian: Colibrì barbuto codabianca; Japanese: agohigehachidori; Dutch: Zwartkeel-baardkolibrie; Polish: pustelnik jasnosterny; Slovak: ciernobrádok bledochvostý; Swedish: Blekstjärtad eremit
Subspecies
- Sooty Barbthroat – Threnetes niger niger (Linnaeus, 1758) / ermitaño barbudo común – Nominate Race – French Guiana and adjacent Brazil
- Bronze-tailed Barbthroat – Threnetes niger loehkeni (Grantsau, 1969)
- Range: North-eastern Brazil north of the Amazon (Amapá)
- Eastern Colombia to northern Peru and adjacent west Amazonian Brazil
- Northeastern Brazil south of Amazon (Pará)
- Central Peru to northern Bolivia
- Southern Venezuela, Guyana and Surinam through Amazonian Brazil to northern Bolivia
- French Guiana and adjacent Brazil (northern Amapá)
- Bronze-tailed Barbthroat – Threnetes niger loehkeni (Grantsau, 1969)
Description
The Sooty Barbthroats averages 10 – 11 cm (3.9 – 4.3 inches) in length.
Its upper plumage is mostly an iridescent coppery-green. At the sides of the head the coppery color is intensified, tying into the coppery-colored throat. The under plumage is paler with greenish-coppery spots.
The Pale-tailed Barbthroat and the Sooty Barbthroat are the only hermits with a black throat which emphasizes the whitish stripe next to the beak down to the throat (commonly referred to as “malar stripe”). The upper breast is dusky bronze-green and the lower breast is buffy white. The central tail feathers are greener than the back with white tips. The outer tail feathers are pale buff and the outermost feathers have a diagonal black band and white tip. The bill is slightly curved and is black with white borders. Its legs are pinkish.
The female’s plumage is generally duller.
Similar species: It looks similar to the Pale-tailed Barbthroat; but has a different tail pattern.
Nesting / Breeding
Hummingbirds in general are solitary and neither live nor migrate in flocks; and there is no pair bond for this species – the male’s only involvement in the reproductive process is the actual mating with the female.
During the breeding season, the males of many Hermit species form leks (= competitive mating displays) and congregate on traditional display grounds. Once a female enters their territory, they display for her. Their display may entail wiggling of their tails and singing. Willing females will enter the area for the purpose of choosing a male for mating. Oftentimes she will choose the best singer.
He will separate from the female immediately after copulation. One male may mate with several females. In all likelihood, the female will also mate with several males. The males do not participate in choosing the nest location, building the nest or raising the chicks.
The female Sooty Barbthroats responsible for building the remarkable cone-shaped nest which hangs by a single strong string of spiders’ silk and/or rootlets from some overhead support, which could be a branch or the underside of the broad leaves of, for example, Heliconia plants, banana trees or ferns about 3 – 6 ft (1 – 2 m) above ground. However, these unusual nests have been found beneath bridges, in highway culverts and even hanging from roofs inside dark buildings. The nest is often near a stream or waterfall. It is constructed out of plant fibers woven together and green moss on the outside for camouflage in a protected location. She lines the nest with soft plant fibers, animal hair and feather down, and strengthens the structure with spider webbing and other sticky material, giving it an elastic quality to allow it to stretch to double its size as the chicks grow and need more room.
The average clutch consists of 1 – 3 white eggs (average 2), which she incubates alone for about 17 days, while the male defends his territory and the flowers he feeds on. The young are born blind, immobile and without any down.
The female alone protects and feeds the chicks with regurgitated food (mostly partially-digested insects since nectar is an insufficient source of protein for the growing chicks). The female pushes the food down the chicks’ throats with her long bill directly into their stomachs.
As is the case with other hummingbird species, the chicks are brooded only the first week or two, and left alone even on cooler nights after about 12 days – probably due to the small nest size. The chicks leave the nest when they are about 23-24 days old. The female raises one brood a season.
Diet / Feeding
The Sooty Barbthroats primarily feed on nectar taken from a variety of brightly colored, scented small flowers of trees, herbs, shrubs and epiphytes. They favor flowers with the highest sugar content (often red-colored and tubular-shaped).
Hermits are “trap-line feeders”. This feeding technique entails visiting flowers along a long route (in this case of up to 0.6 miles or 1 km) – as opposed to most other hummingbird species which generally maintain feeding territories in areas that contain their favorite plants (those that contain flowers with high energy nectar), and they will aggressively protect those areas.
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