The speed of their dive or "stoop" has been accurately measured for the first time by Swiss scientists, and has been shown to reach 115mph.
The figure is considerably lower than that given in many wildlife books, which say peregrines can attain 250mph, but this, and many other top speeds estimated for fast-flying birds, are now regarded as wildly exaggerated.
It still puts the peregrine well ahead of all its competitors. Its stoop kills prey such as ducks or pigeons outright by sheer impact.
The newly published studies accurately measured peregrines hurtling down at rates of up to 51 metres per second,which equates to 115mph.
Dr Matthias Kestenholz of the Swiss Ornithological Institute, one of the scientists who carried out the research, described that as representing "the highest air speed of a bird accurately measured so far".
The peregrines involved in the research were measured with tracking radar, considered to be the most accurate method. It works on the same principle as police radar gunsand locks on to the bird to track its movements.
Peregrines can be seen more easily now in Britain than at any time this century. Although still classed as rare and endangered, there are now estimated to be more than 1,000 pairs - one of Europe's most thriving populations.
Owing to hunting earlier in the century and then the effects of pesticides accumulated from their prey, there were only about 360 pairs in the early 1960s, many of them failing to breed successfully. The recovery followed restrictions being placed on the use of pesticides and it has also been helped by round-the-clock watches of nesting sites to protect them from disturbance.
However, peregrines still suffer problems from nest- robbers, seeking their eggs for illicit collections or young birds for the lucrative overseas falconry trade.
The eider, the coast-dwelling duck, has been found to reach a speed of about 47mph, followed by the Bewick's swan (45mph); the common crane and barnacle goose (42mph); the mallard (40mph); and the red-throated diver (38mph).
Swifts have been credited with rapid flight but their long, thin wings are not ideal for sustained speed. Common swifts, the species nesting in Britain, have been found to fly at just 25mph.Reuse content