A kestrel is a small bird of prey. a type of bird that is like a small falcon (crécerelle, from crécelle ). Any of several birds of prey (genus Falco) known for hovering while hunting. Kestrels prey on large insects, birds, and small mammals. The male is more colourful than the female. Kestrels are mainly Old World birds, but one species, the American kestrel (F. sparverius), often called the sparrow hawk in the U.S., is common throughout North and South America. It is about 12 in. (30 cm) long, white or yellowish below, and reddish brown and slate-gray above with colourful markings on the head. The common kestrel (F. tinnunculus) of the Old World is larger and less colourful. See also falcon