answers: crest
context: the rump is the body immediately above the tail. The color of plumage on the rump is a characteristic widely used by ornithologists to distinguish between related species, and sometimes also between males and females of the same species. Similarly, the silhouette of the tailfan is a characteristic widely used for purposes of identification, particularly in the field. Some birds have a food reservoir pouch in the esophagus that is known as a croup (or crop), which should not be confused with the croup (rump) of a horse. In some breeds it is traditional for tails to be cut off </s> as diastataxis (those that do have the fifth secondary are said to eutaxic). In these birds, the fifth set of secondary covert feathers does not cover any remiges, possibly due to a twisting of the feather papillae during embryonic development. Loons, grebes, pelicans, hawks and eagles, cranes, sandpipers, gulls, parrots, and owls are among the families missing this feather. Tertials arise in the brachial region and are not considered true remiges as they are not supported by attachment to the corresponding bone, in this case the humerus. These elongated "true" tertials act as a protective cover for all or part </s> are probably the most recognizable birds to feature crests. Cockatoos and cockatiels possess crests which may be raised or lowered at will. Their crests are used to communicate with fellow members of their species, or as a form of defense to frighten away other species that approach too closely, making the bird appear larger when the crest is suddenly and unexpectedly raised. Crests can be "recumbent" or "recursive", depending on the species. The recumbent crest has feathers that are straight and lie down essentially flat on the head until the bird fans them out to where they stand up. The
question: what are the feathers on top of a peacock 's head called