Bar-headed geese in high-flying wind tunnel test
Video footage of bar-headed geese in high-altitude wind tunnel experiments has been released by researchers.
The flights were captured in super slow-motion by the University of British Columbia.
During "test flights", birds wear masks they are trained to wear as goslings, which provide them with oxygen levels that simulate high altitude.
The masks also collect gas that the birds breathe out, measuring how much precious oxygen they use in flight.
End Quote Dr Jessica Meir University of British Columbia
I want to uncover the mechanism that allows these incredible physical feats to be accomplished”
BBC Nature spoke to lead researcher Dr Jessica Meir at the Society for Experimental Biology's annual meeting in Salzburg.
Dr Meir explained that a great deal of research into the "remarkable geese" revealed how the birds are specially adapted to fly at extremely high altitude.
Their blood, for example, can carry far more oxygen to their muscles than other birds.
But while most studies have focused on the birds while they are at rest, Dr Meir wanted to create a "picture of oxygen delivery while the bird is flying".
Fortunately for her, the university's engineering department has a wind tunnel wide enough for a goose - with a wingspan of more than 1.5m - to fly in.
Tracking studies have recorded the birds at heights of 6,000m (just under 20,000 feet) - something they need to achieve in order to complete their migration through the Himalayas.
Other high altitude wildlife
- Yunnan snub-nosed monkeys - see the bizarre-looking primate that lives at the highest altitudes of any primate other than humans.
- Jumping spider - watch the Himalayan jumping spider hunting at 6,700m above sea level.
- Ancient bristlecones - see the world's oldest trees that have survived 5,000 years of harsh, high altitude conditions.
But, in order to find out just how high the birds could fly, Dr Meir and her colleagues recreated the oxygen and nitrogen levels that the birds would receive at 6,000m and at 9,000m above sea level. This is approximately 10% oxygen and 7% oxygen respectively.
At 7% oxygen, the birds are experiencing the conditions required to fly over the summit of Mount Everest.
Dr Meir told BBC Nature that she was interested in the physiology that allowed animals to cope in extreme environments and "do amazing things".
"I want to uncover the mechanism that allows these incredible physical feats to be accomplished," she said.
"We already know they fly at up to 6,000m, where the oxygen levels are half what they are at sea level.
"And they're not only able to function, they're able to fly, which is an incredibly expensive way of moving around; it takes 10-20 times more oxygen than when they're resting."
Dr Meir also hopes that understanding how bar-headed geese cope and perform at such low oxygen levels will help inform research into human respiratory problems.