Though the peregrine falcon is described as the fastest animal on Earth, it is not the fastest when in its level flight which is only in the range 40 to 55 mph but in fact, when in its hunting dive. Experiments done have demonstrated that the diving speed of the peregrine falcon exceeds 200 mph. According to an experiment done in 2005 by Ken Franklin, the speed of the falcon reaches a value of 242 mph which is the fastest speed ever observed till now.
The peregrine falcon can measures from 14 to 19 inches (36 to 49 cm) with a wingspan ranging from 3.3 to 3.6 feet (100 to 110 cm). Also, it weighs from 530 to 1600 grams.
Consequently, people might wonder how such a small animal can fly at this subsonic speed? The answer lies in its ability to morph its wing.
The peregrine falcon can fly at an altitude of over 3500 feet . Initially, before diving, the falcon brings its wings close to its body. During its descent, as its speed increases, one wing tends to be pushed forwards with its head tucked in to that side while the other wing is pulled back. As for the tail, it is folded and the feet is tucked in. Consequently, that manoeuvre streamlines the bird by decreasing its cross-section presented to the air. The body of the falcon becomes more aerodynamic and air resistance is minimized.
Another interesting question that people might point out is how is the body of the peregrine falcon adapted to perform a stoop at this speed? The falcon has special adaptations in its nostrils which allow it to breathe at such tremendous speed. Each nostril contains a rod and two fins behind it. As air rushes past the nostrils, the flow is broken up and slowed by the rods and fins which enable the falcon to breathe normally without being overwhelmed by the force at which air enters its nostrils. Moreover, the eyes of the peregrine falcon are designed so that the falcon has a clear view of its prey throughout the dive. Each eye is equipped with an nictitating membrane which protects it from dust and other debris in the air and an additional secretory gland to prevent drying up of the cornea. The dark markings around its eyes also reduce glare, improving visual contrast.
Here is a video of a peregrine falcon attacking a red-tailed hawk which is too near to its nest. Note that the red-tailed hawk is larger that the peregrine falcon with a body length of 18 to 26 inches , wingspan of 3.2 to 3,6 feet and weighs 690 to 1460 grams but this fact does not prevent the peregrine falcon to attack.
Quite an amazing video isn’t it?
Observe the extraordinary speed at which the falcon strikes the hawk. Slow motion videos show that the falcon spreads its toes open to grab the prey at the moment of contact but because of the high speed at which this occurs, it instead rakes the prey, usually with its hind talons. Since this happen so fast, it seems like the falcon is performing a closed-foot strike.