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coat, and furrowed on the inside'. In this receptacle the food is completely ground and reduced to a pulp. The lungs of birds differ from those of quadrupeds in not being loose or free in the breast, but fixed to the bones all the way down :--they consist of a pair of large spongy bodies, covered with a membrane, which is pierced in several places, and communicates with several large vesicles or airbags, dispersed about the cavities of the body.
The eyes of birds are more or less convex in the different tribes; and, in general, it may be observed, that the sense of sight is more acute in birds than in most other animals. Birds have no outward ear, but the internal one is formed on the same general plan as in quadrupeds. Birds are oviparous animals, always producing eggs, from which the young are afterwards excluded. The first appearance of the young, as an organized body, begins to be visible in six hours after the egg has been placed in a proper degree of heat, under the parent animal. The chick, or young bird, when arrived at its full size, and ready for hatching, is, by Nature, provided with a small and hard protuberance at the tip of the bill, by which it is enabled the more readily to break the shell, and which falls off some hours after its hatching.
From the diminutive size and slender conformation of birds we might be led to suppose, that the duration of their life would prove but short; the reverse, however, is the case: their longevity far exceeds that of quadrupeds, and even of man himself. The common cock has been known to live upwards of twenty years; a linnet, fourteen; bullfinches, twenty; parrots are said to live forty years; geese, fourscore: of swans, eagles, and ravens, there are various reports; some have asserted, that they lived
* In the birds of prey or accipitres this is wanting, the stomach being allied to that of quadrupeds.
· one hundred years, others double and even three times that period; but of this there are few well attested examples.
Nestling and Jncubation.
variety in this to be fouation. Amen.deservedly
The nidification of birds has been deservedly the subject of much admiration. Among the different orders there is to be found almost every imaginable variety in the situation, structure, and materials of which the nests are composed. Such, however, is the uniformity with which instinct proceeds, that the same species, in all countries, build their nests not only of the same shape, but as far as possible with the same materials. In the red-breast, and some other birds, where a small variation in their mode of architecture has been perceived, it has always been found to be the result of necessity. Where oak leaves are found in plenty, the former prefers them; if not, he supplies the want by moss and hair. In general, the structure of the nest is adapted to the number of eggs, the temperature of the climate, and the heat of the animal's body which is to occupy it.
When the bird is of small size, and its eggs are numerous, the nest must be proportionably warm, that they may all equally partake of the vivifying heat. Hence the wren, and many of the smaller birds, construct their little edifices with great care, and with very warm materials; whereas the plover and the eagle, whose eggs are so few, that the body may easily be applied to them, build with no solicitude; some, in these circumstances, leave them upon the naked rocks. The climate has also its influence on the nestling of birds: many of those water-fowl, that with us construct their nests in a careless manner, discover greater solicitude in the colder climes of the north, where they strip the down off their breasts, to line their nests, and pro
tect their progeny. The instinct and industry of . birds are in nothing more apparent than in the building of their pests. How regular and admirable are these little edifices, formed of such different materials; collected and arranged with such judgment and labour, and constructed with such elegance and neatness, without any other tools than a beak and two feet!
It wins my admiration,
The situation of the nests of birds seems to depend greatly upon their habits of life, the vicinity of food, and their security from the invasion of their enemies. Some build upon the ground, as the gallinaceous tribes and water-fowl; others build under the ground, as the sand martin and puffin ; which last becomes the tenant of a rabbit's hole. By far the greater number build in bushes, or on rocks: but a few species, like the water-hen, perform incubation on the surface of the water, their nests being attached to a few reeds. The larger rapacious birds, who live in perpetual hostility with all nature around them, repair, at the breeding season, to the inaccessible rocks and precipices, where they have least to fear from man, and those numerous tribes of animals with whom they are constantly at war. In the thick and luxurious woods of the warmer climates, where birds have little to fear but from the serpent or the monkey tribes, some, especially. of the gross-beak tribes, build their nests pendulous from the extremity of the branch of a tree. There, where man is seldom their aggressor, they take no pains to conceal them from the eye; their construction is beautiful, and their entrance curiously contrived below, to secure them against the more dangerous invasion of their enemies. But all those birds who live upon fruits and corn, and are too often unwelcome intruders upon the fruits of human industry, are chiefly solicitous in constructing their nests to conceal them from the eye of mankind. Informed by experience with how much severity he checks their encroachments, they seem, by their extreme precaution, to elude his observation, and to regard him as their most formidable enemy.
Some to the holly-hedge
Clean and complete, their habitation grows.
no sooner completed, than they enter upon another process still more tedious and painful. Neither the nature nor extent of the instinct of brutes is fully understood; this principle, however, during the incubation of birds, seems in some respects to approach, if not to surpass, the powers of reason. Nothing can exceed the patience of birds when hatching : during a period which continues from three to eight weeks, neither the approach of danger, nor the calls of hunger, can drive them from the nest. Before incubation is completed, the female, however plump at the beginning, is generally emaciated to a skeleton. Among some tribes, the male and female sit alternately, the more equally to divide the tedious labour: among others, the male provides food for his mate, while hatching, or alleviates her toils by his melody from a neighbouring bush; some join together in the arduous operation, and, by increasing the heat, endeavour to accelerate its progress. At times, however, the eggs acquire a heat that seems hurtful to infant life : on these occasions they are left to cool; and the hen, after a longer or shorter space, according to the weather, again resumes her occupation, with her former perseverance and pleasure.
Mr. Addison, when speaking of the instinct of birds, terms it an immediate direction of Providence; such an operation of the Supreme Being, as that which determines all portions of matter to their proper centre of attraction. It is certain that they scem almost entirely passive under its influence. In obedience to its call, they fly from one appetite to another;, and whatever ingenuity they may seem to possess while acting under it, in every thing beyond its reach they display the utmost dulness, or the greatest stupidity. With how much seeming caution does the hen provide herself a nest in places unfrequented, and free from disturbance! When she