Date: December 8, 2016
Source: University of Faculty of Science British Columbia
Hummingbirds' ability to accelerate and turn diminishes at high altitudes, but it isn't a lack of oxygen to the body that limits the birds' performance -- it's physics.
"It appears the mechanics of high-altitude flight slow down the birds well before their respiratory system has an issue handling the lower-oxygen environment," said zoologist Paolo Segre, author of a new study in Current Biology.
"Just like a helicopter's rotors lose 'traction' at high altitudes with low air densities, the hummingbirds' wings don't perform as well."
Segre and colleagues at the University of British Columbia captured male adult hummingbirds and transported them to the White Mountain Research Centre in California. The centre, situated at 3,800 metres (12,500 feet), allowed the researchers to evaluate the birds' ability to accelerate and turn, and compare them to baselines gathered closer to sea level.
"Hummingbirds' acceleration, rotation and turning skills are key to their ability to compete for food and defend territory," said UBC zoologist Douglas Altshuler, senior author on the paper.
"As climate change continues to increase temperatures around the globe, more and more species will be forced to seek out cooler regions, including at higher elevations."
The elevation of 3,800 metres (12,500 feet) put the birds just beyond the species' maximum range in terms of elevation, but this was enough to dramatically lower the birds' aerial performance.