1. A black vulture (mass = 179 kg) gliding freely in a wind tunnel adjusted its wing span and wing area as its air speed and glide angle changed from 9·9 to 16·8 m/s and from 4·8° to 7·9°, respectively.

  2. The minimum sinking speed was 1·09 m/s at an air speed of 11·3 m/s.

  3. The maximum ratio of lift to drag forces was 11·6 at an air speed of 13·9 m/s.

  4. Parasite drag coefficients for the vulture are similar to those for conventional airfoils and do not support the contention that black vultures have unusually low values of parasite drag.

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