The peregrine falcon (Falco peregrinus) holds the record for the fastest dive by a bird. In optimal conditions, it can achieve a terminal velocity of approximately 320 km/h (200 mph) when executing a diving stoop to hunt prey mid-flight. Experimental dives have even suggested that this fastest bird in the world may be capable of reaching speeds as high as 389 km/h (242 mph).
In 1999, during a series of dives, “Frightful,” a peregrine falcon owned by aviator and falconer Ken Franklin of Friday Harbor, Washington, USA, was reportedly recorded at a speed of 242 mph (389.46 km/h) while stooping from an altitude of approximately 3 miles (4.8 km). Frightful – the fastest bird in the world, then a six-year-old bird measuring 40.64 cm (16 in) in length and weighing 997.9 grams (2.2 lb), had a wingspan of 104.14 cm (41 in).
To measure Frightful’s speed during the dive, Franklin, in collaboration with mathematicians and engineers, employed an innovative technique. A 113.4-gram (4-oz) computer chip, originally part of a skydiver’s Pro-Track recording altimeter/computer, was attached to Frightful’s tail feathers. By measuring the distance Frightful fell within a specific time interval, they could calculate her mid-dive speed. Altimeters were also attached to Franklin, a cameraman who skydived alongside Frightful, and to the lure released to simulate prey for Frightful to pursue. Data from all four devices were compared following the dives.
The dive experiments conducted by Franklin and Frightful were the subject of a National Geographic Explorer documentary titled “Terminal Velocity,” filmed in 1999 and aired in 2002.
While some ornithologists have questioned the validity of these dives, citing that the conditions did not replicate those found in nature, such as starting from a higher altitude than peregrines would typically dive from, Franklin maintained that this was done solely to allow for more extensive observations and had no impact on Frightful’s flight behavior.
