Traditionally, nightjars have been divided into three subfamilies: the Caprimulginae, or typical nightjars with 79 known species, and the Chordeilinae, or nighthawks of the New World with 10 known species. The two groups are similar in most respects, but the typical nightjars have rictal bristles, longer bills, and softer plumage. Their soft plumage is cryptically coloured to resemble bark or leaves, and some species, unusual for birds, perch along a branch rather than across it, helping to conceal them during the day. The subfamilies of nightjars have similar characteristics, including small feet, of little use for walking, and long pointed wings.