falcon, common name for members of the Falconidae, a heterogeneous family of long-winged birds of prey closely related to the hawk. Falcons (genus Falco ) range in size from the 61/2-in. (16.5-cm) falconet to the 24-in. (60-cm) gyrfalcon, and in habits from the swift merlin to the sluggish caracara. True falcons, distinguished by their notched beaks, are widely distributed. In flight their wingbeats are rapid and powerful, and they swoop hundreds of feet at speeds of up to 200 mph (320 kph) to capture their prey—chiefly birds and small mammals. They kill cleanly, usually breaking the back of their victim. Some falcons eat insects; the long-legged caracaras (found in South America, with one species, the crested, or Audubon's, caracara ranging to the extreme S United States) feed also on carrion and sometimes rob other birds of their prey. The cosmopolitan peregrine falcon and the gyrfalcon of the arctic tundra have been much used in falconry. The commonest and smallest American falcon is the American kestrel, or sparrow hawk, F. sparverius (related to the European kestrel). Others are the merlin, or pigeon hawk (related to the European merlin), and the prairie falcon. Falcons build no nests but lay their eggs on the ground, on cliff ledges, or in the abandoned nests of hawks and crows. Falcons are classified in the phylum Chordata, subphylum Vertebrata, class Aves, order Falconiformes.