The Rufous-gaped hillstar (Urochroa bougueri) is a species of hummingbird found in the Andes mountains of South America. With its distinctive orange bill and vibrant green plumage, this petite nectar feeder inhabits high-elevation shrublands and forests.
Introduction
The Rufous-gaped hillstar is one of over 300 species in the hummingbird family Trochilidae. These tiny birds are found only in the Americas, with most species occurring in the tropical regions. The Rufous-gaped hillstar is endemic to the Andes mountains, distributed across Peru, Bolivia, Chile, and Argentina.
This striking hummingbird derives its common name from its most obvious feature – its bright orange bill which contrasts sharply with its dark head. The species name bougueri honors Pierre Bouguer, an 18th century French mathematician and astronomer who traveled to Peru to study the earth’s shape near the equator.
Physical Description
The Rufous-gaped hillstar is a relatively small hummingbird, measuring just 8-10 cm in length and weighing 4-7 grams. As with most hummingbirds, the plumage is sexually dimorphic. The adult male has vivid green upperparts and white underparts, with glittering emerald green gorget (throat feathers). The female is similar but has greyish underparts and lacks the iridescent throat. Both sexes have a short black tail, dark brownish wings, and the distinctive orange bill with a black tip.
Juveniles resemble adult females but have buffy edges to the plumage feathers. The legs of the Rufous-gaped hillstar are covered in whitish feathers up to the toes. This insulating leg plumage helps retain body heat in the cold temperatures of their mountain habitat.
Range and Habitat
The Rufous-gaped hillstar occupies Andean slopes and valleys at elevations between 3000-5000 meters above sea level. Its range extends from central Peru southward through Bolivia and Chile to northwestern Argentina.
This species is associated with montane scrub, grasslands, and forests dominated by Polylepis trees. It occurs in both humid and arid habitats on the eastern and western slopes of the Andes. Stunted trees and shrubs like Chuquiraga, Buddleja, and Baccharis provide abundant nectar and insect sources. The Rufous-gaped hillstar may migrate seasonally to lower elevations.
Feeding Habits
Like all hummingbirds, the Rufous-gaped hillstar has unique anatomical adaptations for nectar-feeding. Its long, slender bill allows access to tubular flowers, while a specialized tongue with forked tips adeptly laps up nectar. Grooves on the inside edge of the bill may help extract insects from foliage.
This species visits a variety of Andean highland plants and will defended feeding territories aggressively. Some frequently utilized nectar sources include red-tubed flowers of the genera Bomarea, Cavendishia, and Centropogon. The Rufous-gaped hillstar also hawks small insects such as flies mid-air. It consumes more insects during the breeding season to obtain protein.
Reproduction and Breeding
The breeding behavior of this hummingbird remains poorly documented, but likely similar to related species. Males perform aerial courtship displays to impress females. Once paired, the female constructs a petite cup nest out of soft plant down and spider webs on a low branch or shrub.
She lays just two tiny white eggs in the nest. Incubation lasts 14-19 days, followed by another 20-23 days till the chicks fledge. The female alone cares for the nestlings, sheltering them under her body to protect from the cold temperatures of their habitat. Like all hummingbirds, the chicks are born helpless and vulnerable, relying completely on their mother for food and warmth.
Conservation Status
The Rufous-gaped hillstar occupies remote and inaccessible terrain over a relatively wide geographic distribution. While some local declines have occurred, its overall population remains stable and the species is listed as Least Concern on the IUCN Red List. Habitat loss from agricultural expansion and grazing are threats in certain parts of its range. This adaptable hummingbird also appears tolerant of moderate habitat disturbance.
Conclusion
The diminutive Rufous-gaped hillstar exhibits specialized adaptations that enable it to thrive in the harsh conditions of the high Andes mountains. Its unique bill has earned it the nickname “orange-billed hillstar” in South America. While tiny, it ably defends flower territories against larger birds or conspecific rivals. This striking hummingbird remains one of the characteristic avian inhabitants of scrubby montane habitats in the Andean region of South America. With further study, there is still much to learn about its ecology and natural history in an environment that remains challenging for researchers to access and observe wildlife.