The Rüppell’s Griffon Vulture (Gyps rueppellii) is a species native to the Sahel region and East Africa, known for its remarkable ability to ascend to heights that dwarf the typical flight ceiling of most birds. It holds a unique place in the study of avian physiology and flight dynamics, earning a reputation among scientists as the highest-flying bird known. The vulture’s routine behavior and its single, dramatic record-setting incident have made it a champion of high-altitude flight.
Defining the Record Altitude
The Rüppell’s Griffon Vulture can fly 37,000 feet (11,300 meters) above sea level. This maximum altitude places it well into the upper troposphere, comparable to the cruising altitude of many jetliners, and far exceeds the 20,000 feet (6,000 meters) the vultures routinely fly. This extraordinary record was established through a singular, tragic event on November 29, 1973, over Abidjan, Côte d’Ivoire. A vulture collided with a commercial aircraft, damaging one of its engines and causing it to shut down. Sufficient feather remains were recovered from the damaged engine, allowing experts at the American Museum of Natural History to positively identify the species. The conditions at this extreme height involve an average temperature of approximately -56 °C, alongside severely reduced oxygen availability.
Physical Adaptations for Extreme Heights
The Rüppell’s Griffon Vulture functions in frigid, low-oxygen conditions due to unique physiological adaptations. At 37,000 feet, the partial pressure of oxygen is less than 10% of the oxygen available at sea level. The bird’s primary adaptation is a specialized variant of hemoglobin in its blood, the protein responsible for oxygen transport. This specialized hemoglobin exhibits an extremely high affinity for oxygen, efficiently binding the sparse oxygen molecules from the thin air. The vulture possesses four distinct hemoglobin components, which create a gradient of oxygen affinities, allowing for maximum oxygen uptake. Furthermore, the avian respiratory system is inherently more efficient than that of mammals, utilizing a cross-current exchange system. This system involves air sacs that ensure a continuous, unidirectional flow of oxygen-rich air over the lungs’ respiratory surfaces during both inhalation and exhalation. The lungs of high-altitude birds also possess a greater concentration of blood vessels and a larger respiratory surface area, which enhances the efficiency of gas exchange.
The Purpose of High-Altitude Soaring
The Rüppell’s Griffon Vulture routinely flies at high altitudes to optimize the search for carrion. Routine soaring flights, often reaching 20,000 feet or more, give the birds a visual advantage, allowing them to scan hundreds of square miles of the African landscape for carcasses. High-altitude flight is achieved with minimal energy expenditure by exploiting thermal currents, which are columns of warm, rising air. By circling within these thermals, the vultures gain altitude effortlessly. Once they reach the desired height, they glide from one thermal to the next, covering vast distances in their search for food. This strategy allows them to travel over 90 miles from their roost to forage.