Below is shown a list of falcon species. Members of the falcon familiy are roughly divisible into three or four groups.
The first contains the kestrels. Kestrels feed chiefly on terrestrial vertebrates and invertebrates of appropriate size, such as rodents, reptiles, or insects.
The second group contains slightly larger (on average) and more elegant species, the hobbies and relatives. These birds are characterized by considerable amounts of dark slaty grey in their plumage; the malar area is nearly always black. They feed mainly on smaller birds.
Third are the Peregrine Falcon and its relatives: large powerful birds which also have a black malar area (except some very light color morphs), and often a black cap also. Otherwise, they are somewhat intermediate between the other groups, being chiefly medium grey with some lighter or brownish colours on the upper side. They are on average more delicately patterned than the hobbies and if the hierofalcons are excluded, this group contains typically species with horizontal barring on the underside.
Very similar to these and sometimes included therein are the 4 or so species of hierofalcons (literally, “hawk-falcons”). They represent taxa with usually more phaeomelanins which impart reddish or brown colors, and generally more strongly patterned plumage reminiscent of hawks. Notably, their undersides have a lengthwise pattern of blotches, lines or arrowhead marks.
Image: List of falcon species (David Ian Roberts)