The sooty barbthroat (Threnetes niger) is a medium-sized hummingbird found in tropical Central and South America. With its predominantly black plumage and striking red throat patch, it is one of the more distinctive members of the hermit hummingbird genus Threnetes. In this article, we will explore the identification, distribution, habitat, diet, behavior, breeding, conservation status, and interesting facts about this unique bird.
Identification
The sooty barbthroat is unmistakable thanks to its velvety black overall plumage. The male has a bright crimson throat patch, called a gorget, which can appear almost luminous in certain lights. The female lacks the red throat and is slightly duller in coloration. Both sexes have a long, straight black bill and whitish tips on the outer tail feathers. The sooty barbthroat averages 10-12 cm in length and weighs 5-7 grams.
The species was first described scientifically by German naturalist Johann Friedrich Gmelin in 1788. Its genus name Threnetes refers to a Greek mythological ferryman who helped souls cross the river Styx, alluding to the rapid wingbeats of these stream-loving birds. The specific epithet niger means “black” in Latin.
Distribution
The sooty barbthroat is found from Mexico south through Central America into tropical South America. Its range extends through the countries of Colombia, Venezuela, Ecuador, Peru, Bolivia, and Brazil. It occurs east of the Andes up to elevations of 1200 meters in forested foothill areas near streams. In Central America, it is patchily distributed in foothill forests from southern Mexico to Panama.
Three subspecies are recognized based on minor plumage and size variations across different parts of the range:
– T. n. niger: nominate, found from Colombia to Bolivia
– T. n. saturatus: found in southeastern Brazil
– T. n. vicinus: found from Costa Rica to western Panama
Habitat
As its common name suggests, the sooty barbthroat prefers dense, dark, humid forest interiors near rushing mountain streams and waterfalls. It rarely ventures into open or disturbed areas. This habitat specificity makes it vulnerable to deforestation. The bird seems to occupy a narrow niche, not competing much with other hummingbird species that occupy more open or flower-rich environments.
Diet
To fuel its fast metabolism, the sooty barbthroat feeds on flower nectar and tiny insects. Favored nectar sources include plants from the Gesneriaceae, Acanthaceae, and Bromeliaceae families. The bird uses its specialized long bill to probe into tubular flowers. It also hawks small insects in flight or picks them from foliage. A technique called “hover-gleaning” allows it to carefully pluck tiny insects and spiders from leaves while hovering in midair.
Behavior
The sooty barbthroat lives solitarily or in pairs, actively defending flower-rich territories from intrusion by other hummingbirds. Males perform elaborate courtship flights to impress females, flying back and forth while vibrating their tails. When threatened, these normally quiet birds may produce buzzing or clicking sounds with their wings. They perch horizontally on low branches, sometimes slowly flicking their tails. Their flight is rapid and direct.
Breeding
The breeding season lasts from March to June across most of the range. The male works to attract a female through aerial displays. Once paired, the female builds a small cup nest out of plant down, fibers, and spiderwebs on a low horizontal branch or tree fern. She lays two tiny white eggs. Incubation lasts 15-19 days. The chicks hatch with eyes closed and almost no feathers. Both parents share feeding duties, regurgitating insect prey to the nestlings. The young fledge at about 22-26 days old.
Conservation Status
The sooty barbthroat is evaluated as Least Concern on the IUCN Red List of Threatened Species. Its population appears stable and it occupies a wide distribution. However, the species merits continued monitoring due to its susceptibility to habitat loss and fragmentation. Its specialized habitat requirements mean deforestation poses a significant threat. The trend toward hydropower dams in the Andes also degrades the rushing stream habitats this species relies on. Eco-tourism and observation of wild hummingbirds can potentially aid conservation efforts.
Interesting Facts
– When incubating eggs, the female sooty barbthroat enters a state of torpor at night to conserve energy. Her metabolic rate drops dramatically and she becomes temporarily unable to fly.
– Sooty barbthroats play an important ecological role as pollinators for many rainforest plant species. As they move between flowers accessing nectar, they carry pollen on their bills and heads.
– Males establish feeding territories averaging around 2500 square meters in size. Within these zones, they actively repel intrusions from other male hummingbirds.
– A recording of the sooty barbthroat’s wing buzzing sounds reached the Billboard charts in the 1990s after being included on a New Age nature music album.
– While collecting plant specimens in Ecuador in 1857, naturalist William Jameson became the first scientist to formally describe the red throat gorget of the male sooty barbthroat.
In summary, the sooty barbthroat is a fascinating rainforest hummingbird known for its dark plumage, crimson throat, specialized habitat, and energetic territorial displays. As development encroaches on its forest home, conserving adequate habitat will be key to ensuring the future survival of this unique species. With a combination of ecotourism potential and intrinsic value, the sooty barbthroat remains a compelling ambassador for the rich biodiversity found across tropical Americas.