The Wire-crested Thorntail (Discosura popelairii) is a small hummingbird found in the Andes mountains of South America. With an average body length of 7-8 cm and weight of 3-4 grams, it is one of the smaller hummingbird species. Its most distinguishing feature is the male’s colorful crest, formed from five or six spiky feathers on the top of the head which can be erected or flattened.
This species has metallic green upperparts and whitish underparts. The male has a velvety black throat, a white breast band, a rufous belly, and vivid iridescent purple and green gorget feathers on the throat that shine when illuminated. Females lack the ornate gorget feathers and have white throat and belly feathers with green flecks on the flanks. Both sexes have a thin dark bill and white postocular spots behind the eyes.
The Wire-crested Thorntail inhabits montane evergreen forests and elfin forests at elevations of 800 to 3300 meters. Their range extends from Venezuela through Colombia, Ecuador, Peru, and Bolivia. They are found in habitats with plenty of flowering plants and feed primarily on nectar, supplementing their diet with small insects.
Reproduction occurs from April through August. Males perform courtship displays, flying in u-shaped patterns to show off their crest and gorget for potential mates. Females build a small cup-shaped nest out of plant down and fibers on the upper surface of a fern or palm frond, laying two tiny white eggs. She incubates the eggs alone for 15-19 days. The chicks hatch with closed eyes, no down, and rely completely on the female for care. They fledge in 18-23 days.
Like other hummingbirds, the Wire-crested Thorntail can hover in still air and fly backwards or upside down briefly. Its wings beat approximately 70 times per second. This rapid flight allows the bird to lick nectar from specialized tubular flowers, utilizing its bifurcated tongue.
These diminutive hummingbirds play an important role as pollinators of native Andean plants. Their habitat is threatened by agricultural expansion, cattle ranching, logging, and human infrastructure. Conservation International lists the Wire-crested Thorntail as a vulnerable species, with population declines estimated between 30-49% over the past three generations. Habitat protection and limiting fragmentation will be important for the preservation of this species.
Despite its small size, the Wire-crested Thorntail is adapted to the cool, windswept paramo and elfin forest environments it inhabits. Specializations like metabolic “torpor” to conserve energy on cold nights, orientation skills to compensate for migration over immense mountains, and anatomical adaptations to extreme elevations make this species a fascinating example of evolutionary biology. Scientists have discovered that hummingbirds can rapidly adapt to high elevation environments over just a few generations.
Characteristics like size and wing aspect ratio vary between Wire-crested Thorntail populations at different elevations. Lower elevation populations tend to be larger, while higher elevation birds are smaller with more rigid, pointed wings for maneuverability. Research has examined the genetic and physiological factors behind these variations. There is evidence that mutation rates may increase at higher elevations, speeding up adaptation.
One study compared Wire-crested Thorntails living at 1200m to those at 3000m and found striking differences. The higher altitude population had heavier skeletons, more dense and efficient muscle composition, and differences in metabolism and oxygen consumption. This demonstrates the significant impact that only 1800 meters of elevation can have.
There are still many unanswered questions about Wire-crested Thorntails and scientists continue investigating their evolutionary history. Analyses of genetic divergence between populations can give insight into how quickly they can adapt. Tracking hummingbird movements between elevations may reveal important migration patterns. There is also limited knowledge about their nesting requirements, mating behaviors, and response to changing flower resources. Continued research and monitoring will be important for understanding and protecting this specialized high elevation species into the future.
In conclusion, the Wire-crested Thorntail is a unique hummingbird exquisitely adapted to life in the towering Andes mountains. Despite its tiny size, this species faces threats from habitat loss and climate change. Their evolutionary history and adaptations provide fascinating examples of how animals specialize to challenging environments. Protecting areas of montane forest and paramo habitat will give the best chance for the continued survival of this endemic hummingbird into the future. Further scientific study of Discosura popelairii will provide greater understanding of physiological adaptation and ecosystem connectivity in the Andes, improving conservation efforts.