Green Guru: How High Do Migrating Birds Fly?
Pilots tell stories of seeing vultures out of airplane windows. Radar shows long-distance migrants flying nearly four miles in the air. Lab studies show that some birds have special adaptations to make use of limited oxygen supplies. How high can some migrating birds get? The Green Guru responds to our reader's question.
How high do migrating birds fly?
—Scott Taylor, Austin, Texas
Birds of all shapes and sizes fly high and low during migration, their flocks filling the skies en route to their nesting grounds. Most songbirds take wing under the protection of darkness, guiding themselves by stars. Raptors soar during the day, often using thermals, or hot air rising from the ground, to propel them while they conserve energy. Most feathered migrants can be found between 700 and 2,000 feet over the lowlands in the Americas. Over Texas, soaring birds of prey from the buteo group, like broad-winged hawks, can climb above 4,000 feet, which may seem even higher to binocular-toting mortals below. Yet long-distance aviators that traverse oceans or mountains regularly reach altitudes of 20,000 feet. Sightings from planes and radar reveal that these birds, like bar-tailed godwits that fly from Alaska to New Zealand, can get close to such heights. Over the Atlantic, a pilot spotted whooper swans at 27,000 feet. Bar-headed geese rise to 30,000 feet, passing over Mount Everest and the Himalayan Mountains on their way from the Tibetan plateau to their wintering grounds in India. The highest honors go to a Ruppell’s griffon vulture. Alas, while cruising over the Ivory Coast at an altitude of 37,900 feet in 1975, this poor soul was sucked into a jet engine. That’s one high and mighty trip.