This is bird note. Right now a flock of bar-headed geese could be flying

over Mount Everest. These champions of high altitude migration leave their

nesting grounds in Tibet and scale the Himalayan range on their way to

wintering grounds in the lowlands of India. With the help of tailwinds they can

cover the thousand-mile trip in a single day. How do these grey-bodied five-pound

geese with zebra-striped heads breathe at such high altitudes? Since pilots in

many mountain climbers need oxygen at half that altitude. Like other birds the

geese have a unique breathing structure adapted to extract oxygen from thin

air even at 30,000 feet. After inhaled air passes through the lungs it's

temporarily stored in several sacks then circulated back through the lungs

extracting still more oxygen. The bar-headed geese also have a special type of

hemoglobin which helps their bodies absorb oxygen quickly at high altitudes and

the capillaries in their breast muscles are more numerous than in other birds

providing the muscles with a greater supply of oxygen. Scientists are studying

the physiology of these high-flying bar-headed geese to look for ways to help

people cope with altitude and respiratory diseases. There's always more to the

story at birdnote.org. I'm Mary McCann.