Bar-headed geese migrate across the Himalayas twice a year, reaching altitudes as high as 7270 metres where the thin air contains just 30 to 50 per cent of the oxygen that air at sea level has.
To understand how they manage this feat, astronaut and physiologist Jessica Meir at NASA鈥檚 Johnson Space Center in Texas and her colleagues raised bar-headed geese from eggs so they would imprint on the researchers. Then they trained the birds to fly alongside a bicycle or in a 30-metre wind tunnel.
After that, they had the geese fly in the wind tunnel wearing a breathing mask that simulated the limited oxygen at altitudes of 5500 and 9000 meters, which mimics the conditions the geese experience when they migrate. The mask also measured the oxygen the birds used and the carbon dioxide they produced.
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The team found that the geese lowered their metabolism during these taxing flights, and their heart rates did not increase. They also found that the blood in the birds鈥� veins cooled as they flew in the wind tunnel with simulated low-oxygen conditions. Cold blood can carry more oxygen than warm blood, which may help the geese fuel the muscles that help them fly.
These test flights were far shorter than wild migration flights 鈥� on average the geese would fly in the wind tunnel for up to 45 minutes, but when they were fully outfitted with sensors and the breathing mask, the experimental flights were just minutes.
鈥淥ur findings have relevance to all physiological and biomedical fields involving animals and humans in low-oxygen environments, such as medical conditions including heart attacks and strokes, or procedures like organ transplants,鈥� said Meir in a statement.
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