October 6, 2024, 12:02 pm | Read time: 4 minutes
Birds, the acrobats of the air, have many amazing abilities. They can glide for kilometers with just one flap of their wings. They plummet like arrows and soar to heights where oxygen is scarce. PETBOOK has investigated how high birds can fly.
Anyone who has ever watched cranes in the sky often wonders how high the birds actually fly. Some people have problems catching their breath at altitudes of 2000 meters or more. What does this look like for birds, and is there an altitude limit above which the animals can no longer fly?
When mountaineers climb Mount Everest in the Himalayas, they need oxygen masks because, at this altitude, the human body is only supplied with 60 percent oxygen. The result is altitude sickness, which causes symptoms such as shortness of breath, fatigue, headaches, and edema in the lungs and brain. The mountaineers Reinhold Messner and Peter Habeler, who climbed the 8848-metre-high summit of Mount Everest in 1978 without a breathing mask, were an exception.
How do birds cope with the lack of oxygen at high altitudes?
Just like humans, birds’ bodies are supplied with oxygen through the lungs and bloodstream, but they have a more efficient respiratory system than we do. Their respiratory system consists of a maximum of twelve air sacs. This system allows a unidirectional flow of air through the lungs, which enables continuous oxygen intake during both inhalation and exhalation. With this so-called countercurrent lung, they can absorb up to 50 percent more oxygen.
In addition, birds have a larger heart in relation to their body than humans. It can, therefore, pump more blood. The capillary density of the heart and flight muscles is also so high that they can be better supplied with oxygen. In addition, they produce more of the hormone erythropoietin (EPO for short) when there is a persistent lack of oxygen. This hormone ensures that the red blood cells contain more hemoglobin, which is responsible for binding oxygen. All birds also try to save energy when flying by using thermal updrafts, which also means they consume less oxygen1
Which bird can fly the highest?
The absolute record holder is the Rüppell’s vulture (Gyps rueppelli). It has a wingspan of about 240 centimeters (7.9 feet) and weighs up to nine kilograms (nearly 20 pounds). It is native to Africa, where it had a remarkable collision with an aircraft over the Ivory Coast in 1973 – at an incredible height of 11,300 meters. The plane managed to land with damage to one of its engines, but unfortunately, the bird of prey did not survive.
Other birds that fly high are cranes. They have been spotted at 10,000 meters. Alpine choughs fly up to 8,000 meters, and bearded vultures have been spotted at altitudes of up to 7,300 meters.2
Which duck can fly the highest?
The Ruddy Shelduck is not a true duck but rather a half-goose, though it belongs to the duck family. It has typical characteristics of ducks, such as digging for food, and also looks similar to a duck. It is originally native to the inner Asian steppes and semi-deserts.
Ruddy Shelducks, which are escapees from captivity, have established several populations in Europe, including in Switzerland. Scientists at the University of Exeter have discovered that the rather inconspicuous Ruddy Shelduck climbs to an altitude of 6800 meters on its routes to warmer climes in order to fly over the Himalayan massif3
This requires enormous muscle power and oxygen. But as mountaineers know, the air gets thinner and thinner higher up. An impressive feat in every respect, but the half-goose seems to like the lofty heights, as it also breeds on plateaus at 5,000 meters4
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Which waterfowl fly even higher?
The whooper swan
The whooper swan weighs up to 12 kg and, despite its weight, manages to fly at an altitude of 8200 meters. During the breeding season, whooper swans stay in the Eastern European and Siberian taiga. In winter, they move on to Central Europe. There, they spend the winter, for example, on the North Sea coast and in the North German lowlands. Breeding pairs are very rare in Germany. The last count was 21.
The bar-headed goose
This is one of the true geese and only weighs up to three kilograms. It migrates between breeding grounds and winter quarters biannually, nesting on the high-altitude plateaus of Tibet, for instance, due to its tolerance for cold. In Germany, they can be found in the English Garden in Munich, among other places. However, when it crosses the Himalayas, it reaches altitudes of up to 9000 meters.