At more than 23,000 feet, why don’t bar-headed geese get hypoxic?

The bar-headed goose migratory path takes it over the Himalayan Mountains each year between China and Mongolia to their Indian breeding grounds. This flight path puts them at 23,917 feet above sea level. University of Exeter led study followed these birds to gain insight into their ability to survive these extreme altitudes in hopes that their findings might have future implications for low oxygen medical conditions in humans.