The fastest flying bird in the world is not the Peregrine Falcon, but the Spine-tailed Swift (Hirundapus caudacutus), also known as the Needle-tailed Swift or the White-throated Needletail. Call it what you like, this Asian bird has been clocked at 171 kph or 106 mph, in a level flight. Ah, but what about the Peregrine Falcon, you ask. The Peregrine Falcon (Falco peregrinus) has been clocked at 390 kph, or 242 mph, in a dive. So, the distinction here is between flying and diving. Is diving really flying? At best, the Peregrine, when flying on the level, can only get up to 110 kph, or 68 mph. In an unofficial internet list, the Peregrine doesn't even make the top ten. Interestingly, six of the top 10 speed-demons are ducks, with speeds ranging up to 129 kph. In the 19th and 20th centuries, the Peregrine Falcon was commonly called the "Duck Hawk", for its taste for duck meat. But how does the Peregrine catch up to those speedy quackers, like the Mergansers and Canvasbacks and Eiders? That's where that diving-speed prowess comes into play. It just gets above its prey, dives, and knocks it out of the sky. It does not have to hit its prey at the top speed of which it is capable. Much slower speeds will do the job and it is less hazardous for the Peregrine, which could knock itself out of the sky also! (Swift photo from Wikipedia)
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