That is not entirely true. When you measure the flight speed of the birds you have to account wind, height and temperature in order to get true speed in still air. Speeds in r
…ange of 100mp/h for merganser or a spine tailed swift are highly unrealistic for low level flight propelled solely on muscle power and are definitely helped by relatively strong winds. It was concluded in one long Peregrine Falcon study that lasted almost 48 years that no pray specie that Peregrine pray upon was faster in level flight. To substantiate that, here is one link where you can see falcons hunting ducks. They dominate the air with ease! http://www.youtube.com/watch?v=G-FZdIrKyBk&feature=related There are no Peregrine Falcons in video, but it is known fact that the Peregrine is faster than Prairie Falcon both in level flight and in a stoop. (MORE)