During a stoop, peregrines may reach speeds of 200 mph. The air pressure from this bullet-like plunge might burst an ordinary bird's lungs. It's thought that the series of baffles in a peregrine's nostrils slow the wind velocity, enabling the bird to breathe while diving. Breeding Biology Peregrines first breed when two or three years old. The pair will return year after year to use the same nesting ledge, called an eyrie, which they defend from predators and other peregrines.
Eyries are usually at least a mile apart.
Lack of suitable nesting sites formerly limited the peregrine population. The same site may be used by successive pairs for many years. One ledge on an island off Wales has been used since at least 1243. Peregrines nest mainly on high cliffs, although some birds have taken up residence on ledges of skyscrapers in large cities. The nest is a scrape, usually in loose soil, sand or vegetation, with no added nesting material.