The Black-tailed Trainbearer (Lesbia victoriae) is a medium-sized hummingbird found in South America. With its long tail feathers and vibrant green plumage, this species is one of the most visually striking members of the hummingbird family.
Range and Habitat
The black-tailed trainbearer is found along the Andes Mountains in Bolivia, Peru, Ecuador and Colombia between elevations of 2500m and 4500m. Its range is restricted to mountain forest and elfin forest habitats. Elfin forests are high altitude tropical forests located above treeline. These moist forests are dominated by short, stunted trees and shrubs.
The trainbearer’s range overlaps with the Bolivian woodstar, another Andean hummingbird species. However, the trainbearer tends to occupy higher elevations than the woodstar. It is also found at lower densities than the abundant woodstar.
The most conspicuous feature of the male black-tailed trainbearer is its exceptionally long tail feathers, called streamers. These thin, wire-like feathers can measure up to 20 cm in length. This is approximately 4 times the length of the rest of the bird’s body. The tail feathers emerge from underneath the normal short tail feathers. When not being displayed, the trainbearer keeps the elongated tail folded and tucked away out of sight.
Males have vibrant emerald green upperparts and crown. The undertail coverts are also metallic green. The throat and breast are a glittering emerald and golden green. The tail streamers are black, providing a striking contrast against the bright green plumage.
Females lack the long tail feathers and vibrant colors of the males. They have duller olive green upperparts, grey underparts and a buffy wash across the throat and breast. The outer tail feathers have white tips.
Like all hummingbirds, the black-tailed trainbearer feeds on nectar from flowers using its specialized long bill. It favors the flowers of endemic plants and shrubs found at high Andean elevations. These include Puya bromeliads, endemic lobelias, and various flowering bushes.
The trainbearer also hawks small insects to supplement its diet with protein. It can be observed hovering in midair over a perch to pick insects off vegetation.
The male’s elaborate tail streamers are used primarily for courtship displays to attract females. When performing its aerial courtship display, the male flies back and forth repeatedly in a U-shaped pattern. The tail streamers whistle as air rushes through the specialized tail feathers.
At the bottom of the U, the male perches facing the female and spreads his tail feathers into a fan shape. The iridescent feathers shimmer in the light. He rapidly flicks his tail feathers from side to side to showcase their length.
The whistling noises, iridescent flashing colors, and rapid tail movements help attract the attention of females during courtship. Once a female chooses a mating partner, the male continues to display his tail feathers during copulation to assert his dominance over rival males.
The black-tailed trainbearer is classified as Least Concern by the IUCN Red List. Its population is estimated to include between 2500-10,000 mature individuals. While some localized declines have occurred, the overall population remains stable throughout most of its range.
Threats to this species include habitat loss from conversion of mountain forests for agriculture and grazing. Climate change may also pose a long-term threat by changing the plant communities and flowering schedules that the trainbearer depends on in sensitive high altitude ecosystems.
The black-tailed trainbearer’s vibrant colors, long tail feathers, and energetic display flights make it a favorite among birdwatchers. Targeted ecotourism activities may help provide an economic incentive for preservation of its specialized elfin forest habitat. Several bird lodges and tour companies offer guided trips to see this highlight hummingbird species in Ecuador and Peru.
Responsible practices should be used to prevent disturbance to breeding birds. Birdwatchers should take care not to approach active nests too closely during the breeding season of November to April. Maintaining forested buffers around territories, water sources, and mineral licks can help reduce impacts from human visitors.
With its bizarre tail streamers longer than its body, the black-tailed trainbearer is one of the most ornate and easily recognized hummingbirds in the Andes Mountains. Its elongated tail feathers have evolved for visual and auditory courtship displays. Conservation of its high altitude habitat and responsible ecotourism practices will help ensure the continued survival of this unique species into the future.