The Rock Feather or Ala cautis is a small species of corioalar bird that dwells in the mouths of caves and near steep cliffs. Its single leg is bent uncommonly and serves as a flexible anchor. The wings are swept in a negative angle which helps maneuvering during slow flight and in narrow spaces. Also, the incident flow of the tail (or, in this case, leg) rudder is improved. The Rock Feather's omnivore diet consists of small insects as well as fruit, berries and seeds. Food is picked with the help of its beak or by stretching out the leg during flight or while hovering in front of the object.