The Chimborazo Hillstar: A High-Altitude Hummingbird

Hummingbirds are commonly thought of as a typical tropical bird family. And for the most part, this perception is accurate – of the 363 species of hummingbirds, the vast majority thrive in tropical environments. But some species inhabit such extreme habitats that few would expect to find tiny, fragile hummingbirds there. The Ecuadorian Hillstar, for example, lives at altitudes of 4,000 to 5,000 meters (13,100 to 16,400 feet) above sea level – heights that are literally breathtaking.

This endemic Ecuadorian species lives above the tree line in a high-altitude grassland ecosystem known as a páramo. At the upper limit of its range, it even reaches the permanent snow line at around 5,200 meters (17,000 feet). It is helped by living almost directly on the equator, but life at such extreme altitudes nonetheless presents numerous challenges for this small, warm-blooded creature. The most pressing of these are low oxygen levels, limited food availability, and the cold – especially at night.

To cope with these conditions, Hillstars have developed several physiological adaptations. The smaller an animal, the harder it is to retain body heat, since heat loss increases with a higher surface-to-volume ratio. Most hummingbird species weigh between 2.5 and 6.5 grams (0.09-0.23 oz), with some lowland species dropping below two grams. But the harsh mountain environment has shaped the Ecuadorian Hillstar into a relatively robust bird, tipping the scales at around 8 grams – similar to the smallest passerines, such as the Eurasian Wren. This helps it stay much warmer in the cold.

However, getting enough calories from nectar, pollen, and small arthropods to keep the hummingbird alive is a daily challenge. So, Hillstars conserve energy wherever they can. For the Hillstar, the high-speed, energy-intensive hovering that is typical of most hummingbirds is often replaced by clinging to the flower while feeding.

Still, the activity of these hummingbirds is incredible. To compensate for reduced oxygen levels, the Hillstar has extremely fast heart and respiratory rates. To put their abilities into perspective, consider this: The human heart, which weighs about 0.5% of our total body mass, can temporarily sustain a heart rate of around 180 beats per minute. A hummingbird’s heart, which is up to ten times larger in proportion to their body, can exceed 1,000 beats per minute. That’s like putting a Formula 1 engine into a child’s pedal car.

A similar contrast exists in breathing rates. While humans take about 16 to 20 breaths per minute, a resting hummingbird breathes around 300 times per minute, and during flight, this rate can surpass 500.

Such a high-performance metabolism demands a constant supply of energy-rich fuel. But at these altitudes, flowering plants are scarce. One of the few hardy species that the Chimborazo Hillstar depends on is Chuquiraga (Chuquiraga jussieui). Since this plant rarely forms large patches, Hillstars fiercely defend their feeding territories.

Interestingly, although hummingbirds struggle with heat loss, their super-efficient metabolism and powerful muscles also have a problem with overheating. This explains why they have fewer contour feathers compared to similarly sized songbirds. And down feathers – one of nature’s best insulators – are even completely absent in adult hummingbirds.

It’s one thing to keep the metabolism going during the day, and quite another to survive a 12-hour cold night when temperatures often drop below freezing. For this purpose, Hillstar hummingbirds have a truly remarkable adaptation – torpor. During this brief hibernation, Hillstars and other mountain hummingbird species reduce their metabolism by up to 95%. Heart rate is reduced to about 50 beats per minute and body temperature decreases to 5-10°C (40-50°F). This is a record among birds. Keep in mind that their normal body temperature is higher than ours, so dropping this much is nothing short of extraordinary.

Ecuadorian Hillstars pair this strategy with a meticulous search for natural shelters at night, such as caves or overhangs formed by soil and vegetation. If these shelters are scarce, several Hillstars may gather in the same spot, putting aside their territorial disputes for the night. In the early morning, however, any temporary truces are dissolved, and they begin their territorial aggression with the first warming rays of the sun.

A Few Tips for Photographing High-Altitude Hummingbirds

• Know Their Favorite Plants – Research which flowers your target species prefers. If you find the right plant, chances are you’ll find the hummingbird too.
• Pick a Strategic Spot – Position yourself where you have a clear view of multiple flowers. Hummingbirds tend to visit the same blossoms at fairly regular intervals. Chasing them from flower to flower is a losing game; you’re simply not built for it.
• Look for Perches – Hummingbirds often have favorite resting spots where they pause to survey their feeding territory. Observe their habits, find a good angle, and wait.
• Choose the Right Light – The best conditions for photographing hummingbirds typically occur under a partly cloudy sky, which provides soft, diffused light. Direct sunlight can wash out the iridescent structural colors in their feathers.
• Be There Early – Hummingbirds are most active in the early morning, making them easier to locate and photograph.
• Use a Tripod or Monopod – High altitudes are exhausting. A tripod or monopod will help you stay in the game longer.
• Dress for the Cold – Don’t let the equatorial location fool you. Bring a warm hat, gloves, and a thermos of warm tea. Remember that low oxygen levels make you more susceptible to getting cold.
• Stay Aware of Your Surroundings – The high Andes are home to more than just hummingbirds. Keep an eye out for other fascinating species, like the Andean Condor.