The highest flying bird recorded is a Ruppel's griffon vulture, flying at commercial flight heights, close to 40,000 feet (11 km). The bird collided with a plane in 1975 and did not survive.
Ruppel's griffon vultures are able to fly so high because of a different type of hemoglobin (protein in blood that carries oxygen), which allows them to use oxygen more effectively. After Ruppel's griffon vultures, bar-headed geese fly the highest, reaching up to 20,000 feet (6 km). They are often seen flying over the Himalayas, world's highest mountain range.
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