Bird Nostrils

Information about the Bill or Beak

Get more interesting bird information and facts at The Wonder of Birds

Tbe Bird's Beak or Bill and the Rhamphotheca or Horny Sheath

Bird Nostrils

Sifting Bills, Spatula and Spoonbills

Birds with Strong and Unusual Beaks including Hornbill, Crossbill and Wry Bill

Egg Tooth and Gender Dimorphic Bills

In some birds, especially in the diurnal Birds-of-Prey and in the Parrots, the greater portion of the distal end of the upper beak is hard, while the basal portion is thick and soft-the so-called cere. It is generally very sensitive, and encloses the nostrils. Though mostly bare, it is in some Parrots thickly covered with feathers, and then approaches in structure the ordinary skin.

The neighbourhood of the nostrils is often soft, and produces an operculum by which, in some cases, the external nares can apparently be closed, although no muscles seem to exist there. Such a soft and swollen operculum is a prominent feature in Pigeons, and is very large and curled in Rhinochetus (KAGU).  In the Petrels each operculum forms a more or less complete tube, which may or may not fuse with its counterpart in the middle line, and thus produce an apparently single tube with a longitudinal vertical septum, whence the name" Tubinares." A leathery operculum or valve also occurs in Plovers, in Podargus, many Passeres (especially shown in Meliphagidae), and in the Humming-birds, in the last being covered with feathers. In Caprimulgus each nostril is produced into a short, narrow, and quite soft tube.

Another differentiating feature in connection with the nostrils and the rostrum is the presence or absence of a complete vertical internasal septum. If the septum is complete, which seems to be the primary condition, the right and left nasal cavities are completely separated from each other, and birds having this structure are said to possess nares imperviae. The septum either remains cartilaginous, or it ossifies to a variable extent. Consequently in macerated skeletons, where only the bony parts remain, this character cannot be determined. In comparatively few birds is the ossification complete, but this occurs in the Owls, in Podargus, in some Accipitres, Parrots, and others. When the septum is incomplete, the right and left nostrils communicate with each other, forming nares perviae, as in Phaethon, among the Steganopodes, in the Herons, Grebes, Divers, Grallae (except Rhinochetus), Gaviae, Limicolae, Storks, Flamingos, Anseres, Cathartidae (but not in the Vulturidae and Falconidae), and in many Passeres, especially in the Meliphagidae. In some Pelecaniformes (or Steganopodes as they are also known), for instance in the cormorants, the nostrils are reduced to narrow slits, and this condition is carried to an extreme in the Gannets, the external nostrils being absolutely closed, and the greater portion of the nasal cavity obliterated or filled with cancellated bony tissue; however, the olfactory apparatus is well developed, the inner nostrils or choanae being very wide, and in open communication with the mouth, enabling the Gannet to smell its food when in the mouth.

Various parts of the rostrum have received special names: culmen, the dorsal ridge of the upper bill; apex or tip; dertrum, in which it often terminates; gonys, or more correctly genys, the prominent ridge formed by the united halves of the under jaw, (eg, in Gulls; tornia, the cutting edges of the bill).

The form of the bill exhibits almost infinite variations in size, shape and structure, of which only the most striking modifications can be detailled here. Generally shape and size stand in obvious correlation with the mode of feeding, but gender selection seems to play a great part, and leads to formations which it is often impossible to understand.
Previous... Tbe Bird's Beak or Bill and the Rhamphotheca or Horny Sheath Next... Sifting Bills, Spatula and Spoonbills


Home to the Wonder of Birds

This page ©