Fastest bird (diving)
Peregrine falcon (Falco peregrinus)
320 kilometre(s) per hour
Not Applicable (Not applicable)

The fastest dive by a bird is that of a peregrine falcon (Falco peregrinus), which has been estimated at reaching a terminal velocity in ideal conditions of approximately 320 km/h (200 mph) when in a diving stoop hunting prey on the wing. Some experimental dives have suggested that even higher speeds are possible by this species, perhaps up to 389 km/h (242 mph).

During a series of dives in 1999, "Frightful", a peregrine falcon owned by aviator and falconer Ken Franklin of Friday Harbor, Washington, USA, was reportedly clocked at 242 mph (389.46 km/h) while stooping from c. 3 miles (4.8 km) in the air, after being released from a Cessna 172 at 17,000 ft (5,182 m) above sea level. Frightful, then a six-year-old, 40.64-cm-long (16-in) bird weighing 997.9 grams (2.2 lb), had wings open to a full 104.14-cm (41-in) span.

To measure Frightful's mid-dive speed, Franklin – working with mathematicians and engineers – used an innovative technique, fastening a 113.4-gram (4-oz) computer chip taken from a a skydiver’s Pro-Track recording altimeter/computer to Frightful’s tail feathers and measured how far she fell in a certain time interval. Altimeters were also attached to Franklin and a cameraman, who skydived with Frightful during the dives, as well as the lure released to simulate prey for Frightful to chase. The data from all four devices were compared after the dives.

Franklin and Frightful's dive experiments were the focus of a National Geographic Explorer documentary entitled Terminal Velocity, which was filmed in 1999 and aired in 2002.

Some ornithologists have raised doubts about the dives as not recreating natural conditions, e.g., starting at a higher altitude than peregrines would normally dive from. But Franklin insisted that this was only done in order to allow more time for observations and that it made no difference to Frightful's flight behaviour.