Columba Livia(The Domestic Pigeon)

There are number of varieties of the domestic pigeon which differ from one another in coloration, body proportions, but all the varieties have arisen from the blue rock pigeon due to domestication and artificial selection. Anatomical differences between the various varieties are minute and the following description may be applied to any of the variety in general.

The body is divided into head, neck, trunk and tail, all of which are covered with feathers directed backwards and overlapping one another. The head is small with a rounded and high cranium, which slopes down in front into a prominent beak mad up of upper and lower jaws covered with horny sheath or rhametheca. Between the two jaws is the mouth, which has a wide gape. On the each side of the base of the upper beak does a swollen area of the soft skin, the cere, cover a slit-like nostril? The eyes are very large, each with upper and lower eyelids and a transparent nictitating membrane. All the eyelids are movable. A short external auditory aperture leading into a short external auditory meatus at the bottom of which lies the tympanum. Feathers conceal the auditory aperture.

The neck is long and highly mobile. The trunk is plump, boat-shaped and forms greater part of the body. It bears two pairs of limbs. The are folded against the sides of the trunk when the animal is not flying. Each wing shows the three typical divisions: upper arm, forearm and hand. A fold of skins, the prepatagium stretches between the upper arm and forearm on the anterior or the preaxial border, and a similar fold, the postpatagium stretches between the proximal part of the upper arm and the trunk on the posterior or postaxial border. The number of digits in the hand is reduced and they are closely bound together by the skin. The hind limbs are placed near the posterior end of trunk and support the entire weight of the body when at rest. Each hind limb has a short thigh directed downwards and backwards. The foot is divisible externally into a proximal portion, the tarso-metatarsus and four digits. The first digits or the hallux is directed backwards, and the second, third and fourth forwards. The trunk posteriorly terminates into a short tail, uropygium, which bears a group of long feathers to which the term is "tail"is usually applied. On the dorsal side of the base of the uropagium is a papilla on which opens and oil gland; the secretion of which is used for lubricating the feathers by the beak of the bird. On the ventral surface, at the root of the tail lies the transverse cloacal aperture.

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