The White-bellied Woodstar (Chaetocercus mulsant) is a small hummingbird that is native to the Andes Mountains in South America. With an average body length of only 5-6 cm and weight of 2-3 grams, it is one of the smallest hummingbird species in the world. Despite its tiny size, the white-bellied woodstar exhibits incredible speed and agility in flight, with wingbeat frequencies of up to 80 beats per second.
Physical Description
The most distinctive feature of the white-bellied woodstar is the male’s glittering gorget (throat feathers), which shimmers and flashes iridescent violet, blue, and green in the sunlight. The female lacks a gorget and is more drably colored overall. Both sexes have a short black bill, greenish upperparts, white underparts, and white outer tail feathers. The white-bellied woodstar exhibits slight sexual dimorphism, with the male being slightly larger and more colorful than the female. Juveniles resemble adult females but have buffy edges to their plumage.
Distribution and Habitat
The white-bellied woodstar has a relatively restricted range in the Andes Mountains of Peru, Bolivia, and northwestern Argentina. Its natural habitat is montane forest and elfin woodland at elevations between 1800-4400 meters. It occurs mainly on the eastern slopes of the Andes. Within its elevational band, it frequents meadows, forest clearings, gardens, and stands of flowering plants such as fuchsias and passionflowers.
Feeding Ecology
Like all hummingbirds, the white-bellied woodstar has unique anatomical adaptations for nectar-feeding, including a slender, decurved bill and a long, extensible tongue. It feeds primarily on nectar taken from a variety of flowers such as lupines, salvias, and tree tobacco. It prefers flowers with their corollas oriented vertically, into which it can more easily insert its bill. To supplement its diet with protein, the white-bellied woodstar will sometimes catch small arthropods in flight or glean them from foliage.
Reproduction and Life Cycle
The breeding season of the white-bellied woodstar coincides with peak flowering in its mountain habitat, typically from August to April. Males perform elaborate courtship displays, flying in U-shaped or J-shaped patterns to impress females. Once paired, the female constructs a small cup nest out of plant fibers and moss, attaching it to a vertical stalk or tree fern. She lays just two tiny white eggs, which she incubates alone for 15-19 days. The chicks hatch with their eyes sealed shut but develop rapidly, fledging in just 18-23 days. The female cares for the chicks without any assistance from the male.
Migration Patterns
Most populations of the white-bellied woodstar appear to be resident within their Andean breeding habitat year-round. However, some local altitudinal movements may occur outside the breeding season as the birds follow the flowering of key food plants. There is evidence that the southernmost populations in Argentina migrate northwards in the austral winter.
Conservation Status
The white-bellied woodstar is evaluated as Least Concern on the IUCN Red List of Threatened Species. Its population is suspected to be decreasing moderately rapidly due to habitat loss, but its total population size has not yet approached thresholds for a threatened category. Agricultural expansion, woodcutting, and development pressure continue to degrade and fragment its specialized high-elevation habitat. Climate change may also pose a long-term threat. On a positive note, the white-bellied woodstar adapts readily to human-altered environments and can thrive in gardens. Further research into its population trends and habitat requirements is needed.
Fun Facts
– The white-bellied woodstar has one of the fastest wingbeat frequencies of any bird, up to 80 beats per second! This enables its skillful hovering and midair maneuvering.
– A group of woodstars is called a “bouquet”, referencing their association with flowers.
– The wings of the white-bellied woodstar make a high-pitched whizzing or buzzing sound in flight, which is barely perceptible to humans.
– When feeding, the woodstar’s heart rate can reach up to 1,200 beats per minute.
– The Quechua name for the white-bellied woodstar is “Q’umir chupachi” meaning “little emerald that sucks nectar”.
– The white-bellied woodstar was first scientifically described in 1875 by the French ornithologist Édouard Mulsant.
– Species in the woodstar genus Chaetocercus are some of the smallest hummingbirds in the world, with weights as low as 2 grams.
In summary, the white-bellied woodstar is a tiny and tenacious hummingbird that thrives in cold mountainous habitats of the Andes. Its unique adaptations for hover-feeding on nectar allow it to occupy an important ecological niche. Ongoing conservation efforts for this diminutive species and its specialized habitat will be important in the face of continuing threats. With proper environmental stewardship, the glittering white-bellied woodstar will hopefully remain a fixture of the South American cordilleras for centuries to come.