The Coppery metaltail (Metallura theresiae) is a small hummingbird found in the Andes mountains of Peru and Bolivia. With an average body length of only 9 centimeters, it is one of the smallest hummingbirds in the world. Its name refers to the coppery, metallic coloring on the tail of the adult male.
The Coppery metaltail has a straight black bill and white underparts. The male has a velvety black head and throat, with copper-green upperparts. As the name suggests, the tail is a distinctive coppery-chestnut color with a subterminal black band. The female is similar but has greener upperparts, less black on the head, a buff throat, and a pale grey belly. She lacks the metallic coppery tail of the male.
Both sexes have a small white spot behind the eye. The legs and feet are black. Juveniles resemble adult females but have buffy fringes to their plumage. The Coppery metaltail produces a high-pitched insect-like call while feeding and a whistled “seep” call used for communication.
Habitat and Distribution
This rare hummingbird is endemic to a small region of the Andes in southern Peru and adjacent Bolivia. Its extremely limited range falls within the Eastern Cordillera montane forests ecoregion. It occurs at elevations between 10,800 and 14,700 feet.
The Coppery metaltail inhabits temperate scrublands and grasslands as well as elfin woodland patches dominated by gnarled, wind-swept Polylepis trees. It seems to prefer ravines and rocky outcrops where flowering plants are sheltered. Critical habitat requirements are the presence of flowers and scattered shrubs for feeding, plus a supply of arthropods.
Diet and Feeding
Like all hummingbirds, the Coppery metaltail feeds on nectar from flowering plants. It uses its long, specialized tongue to lap up nectar while hovering in front of flowers. The bill and tongue are perfectly adapted for accessing the nectaries of different shaped flowers.
Favorite nectar sources include shrubs such as the mountain rose Baccharis incarum and small trees like Schinus. The Coppery metaltail will also visit terrestrial flowers when available, such as species in the aster and lupine families.
In addition to nectar, the Coppery metaltail feeds on tiny insects including midges, spiders, beetles, and ants. The insect protein is an essential part of their diet. Insects are gleaned from foliage or caught in flight.
Reproduction and Life Cycle
The breeding season for the Coppery metaltail coincides with the Southern Hemisphere’s spring and summer between October and February. As part of courtship displays, the male flies around the female while singing loudly. If she is receptive to his advances, mating will occur.
The female builds a small, delicate cup nest on a vertical rock face or cliff edge, under a ledge or overhang. The nest is constructed from silky plant fibers bound together with spider webs. Lichen is then adhered to the outside using more silk, camouflaging the nest.
The female lays just two tiny white eggs. She incubates them alone for about 16 to 18 days until they hatch. The chicks are fed regurgitated nectar and insects by the female. They fledge at 22 to 26 days old.
Threats and Conservation
With its extremely small range, specialized habitat requirements, and fragile nest sites, the Coppery metaltail is vulnerable to extinction. The total population is estimated at just 600 to 1,700 adult birds. For this reason, the IUCN Red List classifies it as Endangered.
The paramo grasslands of the Andes are increasingly threatened by agricultural expansion, overgrazing by cattle, and human settlement. Mining projects also pose a risk. Introduced animals such as trout may reduce insect availability. Climate change could alter flower productivity and nesting conditions.
Protecting remaining patches of Polylepis woodland is crucial for safeguarding Coppery metaltail habitat. Declaring its range as a protected area could offer further security. Ecotourism initiatives manage to promote habitat conservation while generating income for local communities. There is also a need for more research into the basic biology and population trends of this rare hummingbird. With proper protection of fragile Andean ecosystems, the unique Coppery metaltail can hopefully continue to survive for future generations.