The Oasis Hummingbird (Sterna oasis) is a small hummingbird species endemic to Peru. With an average body length of only 8-9 cm and weighing around 3-4 grams, it is one of the smallest hummingbird species in the world. This diminutive bird inhabits arid coastal regions and oasis habitats along the southern Peruvian coast, which gives the species its name.
Physical Description
As its small size suggests, the Oasis hummingbird has a very petite and delicate build. Its slender, pointed bill is adapted for drinking nectar from flowers. The male has iridescent emerald green upperparts and crown, with a bright white underside from chin to belly. Its tail is mostly rufous-colored with some central green feathers. Females are similar but less vibrantly colored, with more gray-green plumage above and whitish below with faint streaks on the throat. Juveniles resemble adult females but with cinnamon edges to the feathers above.
In terms of distinguishing features, the Oasis hummingbird has a short black bill, rufous outer tail feathers, and extensive white underparts compared to similar species. It is most likely to be confused with the Peruvian sheartail, which overlaps in range. However, the sheartail is slightly larger with a more deeply forked tail and more black flecking on the underside.
Range and Habitat
As mentioned earlier, the Oasis hummingbird is endemic to a narrow coastal strip of southwestern Peru. Its breeding range extends approximately 500 km from the Ocoña River valley south to the Caplina River. Within this range, the species frequents dry tropical scrub forests, arid woodlands, and lush oasis habitats centered around water sources. It occurs from sea level up to 1200 m in elevation.
Outside of the breeding season, the Oasis hummingbird undertakes altitudinal migrations. It moves uphill to higher elevation scrublands and mountain valleys, likely tracking the flowering of nectar plants. However, little is known about these seasonal movements or the extent of migratory routes. There have also been rare sightings in northern Chile which indicate some individuals may cross the border outside of the breeding season. But the Oasis hummingbird remains rare and localized even within its core Peruvian range.
Diet and Feeding
Like all hummingbirds, the Oasis hummingbird subsists primarily on nectar from flowering plants. It favors plants in the cactus and bromeliad families, using its specialized tubular tongue to drink nectar while hovering in front of flowers. Some favored food plants include species of Puya bromeliads, Echeveria succulents, and Trichocereus cacti. The long bill allows it to access nectar from longer tubed flowers.
The Oasis hummingbird supplements its diet with small insects like gnats, aphids, and spiders. It gleans these off foliage and also hawks flying insects in mid-air. The protein gained from insects is an important part of its nutrition, especially during the breeding season when energy demands are higher.
Unique Behaviors
One of the Oasis hummingbird’s more peculiar behaviors is its tolerance for higher temperatures than most other hummingbird species. It is regularly observed feeding at flowers even when ambient temperatures exceed 40°C in the desert environment. The evolutionary reasons for this heat tolerance are not fully understood but may relate to reduced competition and increased access to food resources at hotter times of day.
Oasis hummingbirds are also territorial and may defend favored nectar-producing plants or patches of desert scrub from intrusion by other individuals. Males perform display dives and rapid ascents to deter rivals or attract females. However, they do not engage in elaborate courtship rituals or aerial chases like some larger hummingbird species.
Reproduction and Breeding
The Oasis hummingbird breeds between February and April at the end of the wet season. As the name indicates, nesting is closely tied to the presence of moist oasis habitats within its desert environment. The small cup-shaped nest is constructed primarily by the female using downy plant fibers and spider webs as binding material. It is lined with soft plant down and usually placed in a shrub or small tree 2-4 meters above ground.
Clutch size is two tiny white eggs. Only the female incubates the eggs for about 16 days until hatching. The chicks are fed regurgitated nectar and insects by the female. They fledge at around 20-22 days after hatching. Oasis hummingbirds likely only raise one brood per season. Lifespan in the wild is not well documented but is likely 3-5 years based on related species.
Conservation Status
The Oasis hummingbird has a very restricted range and its total population is estimated at only 2500-10,000 mature individuals. Its habitat is threatened by urban development, water diversion projects, and agriculture in the arid coastal valleys of Peru. For these reasons, the Oasis hummingbird is classified as Endangered on the IUCN Red List of Threatened Species.
There are no legal protective measures currently in place for the species or its habitat. Some believe ecotourism may help provide an incentive for conservation of remaining oasis habitats. Careful water management and halting habitat destruction are critical to protecting the long-term survival of the Oasis hummingbird in Peru’s rapidly developing coastal regions. More research and surveys are needed to better understand its movements, population trends, and response to ongoing habitat degradation.
Key Facts
– Tiny hummingbird endemic to arid coastal Peru
– One of the smallest hummingbird species in the world
– Favors dry tropical scrub, woodlands, and lush oasis habitats
– Feeds on nectar from desert flowers and small insects
– Unique heat tolerance allows feeding at high temperatures
– Breeds in oasis areas from February to April
– Constructs tiny cups nests in trees and scrubs
– Classified as Endangered with population under 10,000
– Threatened by urbanization and water diversion in coastal valleys
– More research needed on movements and population trends
In summary, the Oasis hummingbird is a diminutive and unique species that is highly adapted to the arid environments of coastal Peru. Despite its small size, this delicate hummingbird plays an important role as a pollinator of desert plants. However, habitat loss and fragmentation have put the Oasis hummingbird at risk of extinction. Protecting its limited oasis breeding grounds from development and disturbance will be key to ensuring the persistence of this endemic Peruvian hummingbird into the future. More extensive surveys, population monitoring, and ecological research are needed to support evidence-based conservation plans for the species.