THE NATURAL HISTORY OF DOMESTIC FOWLS.
Fowls are classed by modern naturalists as follows:
Division. Vertebrata—possessing a back bone.
Class. Aves—birds.
Order. Rasores—scrapers.
Family. Phasianidæ—Pheasants.
Genus. Gallus—the cock.
Birds, as well as quadrupeds, may be divided into two great classes, according to their food: the Carnivorous and the Graminivorous. Fowls belong, strictly speaking, to the latter.
In the structure of the digestive organs, birds exhibit a great uniformity. The œsophagus, which is often very muscular, is dilated into a large sac—called the crop—at its entrance into the breast; this is abundantly supplied with glands, and serves as a species of first stomach, in which the food receives a certain amount of preparation before being submitted to the action of the proper digestive organs. A little below the crop, the narrow œsophagus is again slightly dilated, forming what is called the ventriculus succenturiatus, the walls of which are very thick, and contain a great number of glands, which secrete the gastric juice. Below this, the intestinal canal is enlarged into a third stomach, the gizzard, in which the process of digestion is carried still farther. In the graminivorous birds, the walls of this cavity are very thick and muscular, and clothed internally with a strong, horny epithelium, serving for the trituration of the food. The intestine is rather short, but usually exhibits several convolutions; the large intestine is always furnished with two corea. It opens by a semicircular orifice into the cloaca, which also receives the orifices of the urinary and generative organs. The liver is of large size, and usually furnished with a gall-bladder. The pancreas is lodged in a kind of loop, formed by the small intestine immediately after quitting the gizzard. There are also large salivary glands in the neighborhood of the mouth, which pour their secretion into that cavity.
The organs of circulation and respiration in birds are adapted to their peculiar mode of life; but are not separated from the abdominal cavity by a diaphragm, as in the mammalia. The heart consists of four cavities distinctly separated—two auricles and two ventricles—so that the venous and arterial blood can never mix in that organ; and the whole of the blood returned from the different parts of the body passes through the lungs before being again driven into the systemic arteries. The blood is received from the veins of the body in the right auricle, from which it passes through a tabular opening into the right ventricle, and is thence driven into the lungs. From these organs it returns through the pulmonary veins into the left auricle, and passes thence into the ventricles of the same side, by the contraction of which it is driven into the aorta. This soon divides into two branches, which, by their subdivision, give rise to the arteries of the body.
The jaws, or mandibles, are sheathed in a horny case, usually of a conical form, on the sides of which are the nostrils. In most birds, the sides of this sheath or bill are smooth and sharp; but in some they are denticulated along the margins. The two anterior members of the body are extended into wings. The beak is used instead of hands; and such is the flexibility of the vertebral column, that the bird is able to touch with its beak every part of its body. This curious and important result is obtained chiefly by the lengthened vertebræ of the neck, which, in the swan, consists of twenty-three bones, and in the domestic cock, thirteen. The vertebræ of the back are seven to eleven; the ribs never exceed ten on each side.
The clothing of the skin consists of feathers, which in their nature and development resemble hair, but are of a more complicated structure. A perfect feather consists of the shaft, a central stem, which is tubular at the base, where it is inserted into the skin, and the barbs, or fibres, which form the webs on each side of the shaft. The two principal modifications of feathers are quills and plumes; the former confined to the wings and tail, the latter constituting the general clothing of the body. Besides the common feathers, the skin of many birds is covered with a thick coating of down, which consists of a multitude of small feathers of peculiar construction; each of these down feathers is composed of a very small, soft tube imbedded in the skin, from the interior of which there rises a small tuft of soft filaments, without any central shaft. These filaments are very slender, and bear on each side a series of still more delicate filaments, which may be regarded as analogous to the barbules of the ordinary feathers. This downy coat fulfils the same office as the soft, woolly fur of many quadrupeds; the ordinary feathers being analogous to the long, smooth hair by which the fur of these animals is concealed. The skin also bears many hair-like appendages, which are usually scattered sparingly over its surface; they rise from a bulb which is imbedded in the skin, and usually indicate their relation to the ordinary feathers by the presence of a few minute barbs toward the apex.
Once or twice in the course of a year the whole plumage of the bird is renewed, the casting of the old feathers being called moulting. The base of the quills is covered by a series of large feathers, called the wing coverts; and the feathers of the tail are furnished with numerous muscles, by which they can be spread out and folded up like a fan. In the aquatic birds—like the goose, the duck, and the swan—the feathers are constantly lubricated by an oily secretion, which completely excludes the water.
In their reproduction, birds are strictly oviparous. The eggs are always enclosed in a hard shell, consisting of calcareous matter, and birds almost invariably devote their whole attention, during the breeding season, to the hatching of their eggs and the development of their offspring; sitting constantly upon the eggs to communicate to them the degree of warmth necessary for the evolution of the embryo, and attending to the wants of their newly-hatched young, until the latter are in a condition to shift for themselves.
In the structure and development of the egg there is a great uniformity; but there is a remarkable difference in the condition of the young bird at the moment of hatching. In the class under consideration, the young are able to run about from the moment of their breaking the egg-shell; and the only care of the parents is devoted to protecting their offspring from danger, and leading them into those places where they are likely to meet with food.
The longevity of birds is various, and, unlike the case of men and quadrupeds, seems to bear little proportion to the age at which they acquire maturity. A few months, or even a few weeks, suffice to bring them to their perfection of stature, instincts, and powers. Domestic fowls live to the age of twenty years; geese, fifty; while swans exceed a century.
The order Rasores includes the numerous species of gallinaceous birds, and the term is applied to them from their habit of scratching in the ground in search of food. They are generally marked by a small head, stout legs, plumage fine, the males usually adorned with magnificent colors, and the tails often developed in a manner to render the appearance extremely elegant. The wings are usually short and weak, and the flight of the birds is neither powerful nor prolonged. The corla of this order are larger than in any other birds.
The species are found in almost all parts of the world, from the tropics to the frozen regions of the north; but the finest and most typical kinds are inhabitants of the temperate and warmer parts of Asia. They feed principally on seeds, fruit, and herbage, but also, to a considerable extent, on insects, worms, and other small animals. Their general habitation is on the ground, where they run with great celerity, but many of them roost on trees. They are mostly polygamous in their habits, the males being usually surrounded by a considerable troop of females; and to these, with a few exceptions, the whole business of incubation is generally left. The nest is always placed on the ground in some sheltered situation, and very little art is exhibited in its construction; indeed, an elaborate nest is the less necessary, as the young are able to run about and feed almost as soon as they have left the egg; and at night or on the approach of danger, they collect beneath the wings of their mother. Most of these species are esteemed for the table, and many of them are among the most celebrated of game birds.
The pheasant family, of this order, includes the most beautiful of the rasorial birds; indeed, some of them may, perhaps, be justly regarded as pre-eminent in this respect over all the rest of their class. In these, the bill is of moderate size and compressed, with the upper mandible arched to the tip, where it overhangs the lower one; the tarsi are of moderate length and thickness, usually armed with one or two spurs; the toes are moderate, and the hinder one short and elevated; the wings are rather short and rounded, and the tail more or less elongated and broad, but frequently wedge-shaped and pointed. The head is rarely feathered all over; the naked skin is sometimes confined to a space about the eye, but generally occupies a greater portion of the surface, occasionally covering the whole head, and even a part of the neck, and frequently forming combs and wattles of very remarkable forms. In some species, the crown is furnished with a crest of feathers.
The birds of this family are, for the most part, indigenous to the Asiatic continent and islands, from which, however, several species have been introduced into other parts of the globe. The Guinea Fowl of Africa, and the Turkeys of America, are almost the only instances of wild Phasianidous birds out of Asia. Some species, such as the Domestic Fowl, the Peacock, the Turkey, and the Guinea Fowl, have been reduced to a state of complete domestication, and are distributed pretty generally over the world.