How High Can Birds Fly? Altitude Records Explained

Highest bird flights on record

Measuring how high a bird flies is difficult, so reliable records are few. The best come from collisions with aircraft, radar, and modern tracking devices that record altitude.

Some claims are higher. Common cranes are often said to cross the Himalayas at around 10,000 m (33,000 ft), but this is not backed by tracking data and should be treated as unconfirmed.

The record holder: Rüppell’s vulture

On 29 November 1973, an airliner flying over Abidjan, Ivory Coast, at about 11,300 m (37,000 ft) hit a large bird. Feathers recovered from the engine were identified as those of a Rüppell’s vulture. The plane landed safely.

At that height, air pressure is only about a fifth of that at sea level, so each breath holds far less oxygen, and the temperature is around −56 °C (−69 °F). Rüppell’s vultures often soar at up to about 6,000 m (20,000 ft) while searching for carcasses across African savannas, using thermals to climb. They carry a special form of hemoglobin, the oxygen-carrying protein in blood, that binds oxygen strongly in thin air.

Sadly, this record holder is now Critically Endangered. Its numbers have fallen steeply because of poisoning, habitat loss and trade in vulture parts.

Bar-headed geese: over the Himalayas

Bar-headed geese breed on the high lakes of Central Asia and winter in India, crossing the Himalayas twice a year. They are often said to fly over Mount Everest at 8,848 m (29,029 ft), but that claim is based on second-hand reports.

When scientists fitted geese with satellite and GPS tags, they found a more careful strategy. In one study of 91 geese, the birds spent 95% of their time below about 5,800 m (19,000 ft), following valleys and high passes rather than crossing summits. Only one bird went above 6,500 m (21,300 ft), reaching about 7,290 m (23,920 ft). The geese often climbed at night and early morning, when cold, dense air gives more lift and oxygen.

Even so, these flights are extraordinary. Geese have crossed from lowland India to the Tibetan Plateau in as little as seven hours of non-stop flight, climbing steeply the whole way.

How do birds breathe thin air?

Birds are much better at high altitude than mammals. Several features help:

• One-way airflow. Birds have air sacs that push air through the lungs in one direction, so fresh air is always flowing past the gas-exchange surfaces. Mammal lungs mix fresh and stale air.
• Oxygen-hungry blood. High-flying birds such as bar-headed geese and Rüppell’s vultures have hemoglobin that grabs oxygen even when there is little of it.
• Deeper breathing. Bar-headed geese breathe more deeply, not just faster, in low oxygen.
• Dense blood vessels. Their flight muscles and hearts have many tiny capillaries, so oxygen reaches the muscle cells quickly.
• Wing shape. Large wings for their weight reduce the power needed in thin air, although birds still have to flap harder at high altitude.

Swifts and condors: high fliers of everyday skies

The common swift spends most of its life in the air. On summer evenings and before dawn, swifts climb to around 2,000–3,000 m (6,600–9,800 ft), probably to sense wind and weather and to rest on the wing. Learn more in do swifts ever land?

The Andean condor roosts and nests on cliffs as high as about 5,000 m (16,400 ft) and soars over even higher Andean ridges, riding thermals with almost no flapping. Other soaring birds, such as Himalayan griffon vultures and golden eagles, also regularly fly at several thousand meters over mountains.

How high do most birds fly?

Most birds spend their lives close to the ground, feeding and moving within the height of trees, cliffs or a few hundred meters above them. Migration is different: radar studies show that most migrating birds fly from a few hundred meters up to about 3,000 m (10,000 ft), choosing heights with favorable winds.

Some songbirds surprise scientists. In a 2021 study, great reed warblers crossing the Sahara flew at night at normal heights, then climbed to as high as about 6,000 m (19,700 ft) during the day, probably to escape the heat near the ground.

Why fly so high?

Birds climb high for a few main reasons: to cross mountains, to catch fast tail winds, to find cooler air, or to gain height for gliding. The whooper swans tracked off Scotland in 1967 were riding a strong jet-stream wind from Iceland, which likely cut their journey to Ireland to about seven hours. Height is costly, though, so most birds fly only as high as they need to.