Birds
Andean Hillstar
Oreotrochilus estella · also called Andean hillstars
Shutting down its own metabolism overnight to survive freezing high-Andean temperatures, an Andean hillstar forages for nectar at altitudes where the air holds barely enough oxygen for most other hummingbirds to function at all.
Overview
The Andean hillstar, Oreotrochilus estella, is a Least Concern bird native to mountain habitat across the high Andes of Peru, Bolivia, Chile, and Argentina. Its tolerance for extreme high-altitude foraging, its nightly deep torpor, and its larger-than-typical hummingbird build make it one of the more physiologically extraordinary birds found anywhere in the world.
A hummingbird that switches itself off each night
While most hummingbirds rely on near-constant feeding to fuel their famously fast metabolism, the Andean hillstar instead shuts much of that metabolism down every night, entering a deep torpor that lets it survive high-Andean cold no ordinary hummingbird strategy could withstand.
Status
Least Concern, remaining widespread and generally stable across suitable high-altitude habitat throughout the Andes.
Andean Hillstar: common questions
How high in elevation does the Andean hillstar live?
This species forages above 4,000 metres in elevation, tolerating thin air with far less oxygen than most other hummingbird species ever encounter.
How does the Andean hillstar survive freezing nights?
This species enters a state of deep torpor overnight, dramatically lowering its body temperature and metabolic rate to survive the freezing conditions typical of high-Andean nights.
Why is the Andean hillstar larger than many other hummingbirds?
This species is relatively large for a hummingbird, an adaptation that helps it retain heat more effectively than smaller hummingbird species could manage at the same extreme altitude.
Where does the Andean hillstar roost at night?
This species roosts in sheltered rock crevices or small caves overnight, seeking additional protection from wind and extreme cold beyond what torpor alone provides.