CHAPTER XII. THE RABBIT: A TYPICAL MAMMAL.

43. THE RABBIT: HABITS AND APPEARANCE.

1. =The habits of the wild rabbit.=—In what places have you known wild rabbits to have a _warren_? In what kind of ground is a rabbit warren generally found? How can you recognise it? Are all the holes of the warren of similar size, or can you distinguish between main entrances and “bolt-holes”? Look for smooth paths, perhaps nine inches wide, which lead to the main entrances and intersect each other, so as to form “runs.” Watch the animals feeding and playing; to do this successfully it will be necessary to keep very still and silent; avoid walking on the runs. What do the rabbits eat? Do they walk, or hop? How do they run? Notice how conspicuous is the white tail of a running rabbit. In June look for a nest of young rabbits. The position of such a nest may often be recognised, when the doe is away from home, by a smooth patch of earth with which she has covered up the hole. Dig up this very carefully and notice how the nest is lined. Examine the young ones without hurting them, and then cover them up again.

What is the _colour_ of a wild rabbit? Does the colour render the animal less conspicuous? Are tame rabbits so often of this colour? Why not? Watch a tame rabbit, noticing especially the movements of its nostrils, whiskers, and ears, and its method of feeding. Try to see how it gnaws the bars of its hutch.

2. =Fur.=—Examine a dead rabbit. With what is the skin covered? What are the differences between the fur of a rabbit, the hair of a dog, and the wool of a sheep? Is fur curly? Does it lie flat on the skin? Does it consist of different sizes of hair—short, fine hairs and long, thicker ones? What other animals do you know which have fur?

3. =The head.=—(_a_) _The whiskers._—On what parts of the head are the longest hairs found? How do these differ, apart from length, from ordinary hairs? What other common animals have whiskers? Do such animals often make their way through narrow passages? What do you suppose is the use of the whiskers?

(_b_) _The skull._—Feel the bones of the head through the skin, and make out the rounded brain-case, the ridge above and the arch below each eye, and the positions of the jaws.

(_c_) _The external ears._—Examine the large ear-flaps. Notice that the upper parts are thin and almost transparent, and that the lower parts are gristly and lead into the interior of the head.

(_d_) _The eyes._—Notice that the eyes are at the _sides_ of the head. Is this position an advantage to the rabbit? Examine, in each eye, the upper and lower lids; and also, in the angle of the eye next the nose, the _third eyelid_—a fold of white skin. Take hold of this fold with the forceps and see that it is easily pulled over the eyeball. Look in a mirror and see the little fleshy body which occupies a similar position in your own eye; this corresponds to the rabbit’s third eyelid. In the visible part of the rabbit’s eyeball notice the round dark _pupil_ in the middle (contrast the pupil of a cat’s eye); the coloured ring (the _iris_) surrounding the pupil; and the “white” (called the _sclerotic_) surrounding the iris.

(_e_) _The lips and nostrils._—Notice how the upper lip is split in the middle line, so as to show the front teeth. What is the use of the split? Notice the grooves passing from the upper lip to the nostrils.

(_f_) _The inside of the mouth._—Open the rabbit’s mouth and notice:

(i) The two gnawing or _incisor teeth_ in the lower jaw, and the pair of strongly-grooved incisors which are so conspicuous in the upper jaw. Just behind the large, upper incisors two smaller incisors may be felt with the finger. Separated by a wide space from the incisors are the _grinding teeth_—six on each side in the upper jaw, and five on each side in the lower jaw.

(ii) The _tongue_, lying between the halves of the lower jaw.

(iii) The hard _ridges_ running across the fore half of the roof of the mouth.

(iv) The _hairiness_ of the inside of each cheek, between the incisor and grinding teeth.

4. =The neck.=—Notice how the neck enables the head to be turned freely in various directions without the body being moved. Feel through the skin and identify:

(_a_) In front of the neck, the _trachea_ or windpipe, with the _larynx_ or “voice box” at its upper end between the halves of the lower jaw.

(_b_) The bones of the neck-part of the _spine_.

5. =The trunk.=—Feel through the skin and make out the _spine_, the _breast-bone_, and the curved _ribs_ which connect these. The spine, breast-bone, and ribs together form a bony cage which encloses the fore-part (the _thorax_) of the body. The hinder and larger part of the body (the _abdomen_) is not protected by ribs, but the bones of the spine are largest and stoutest in this part of the body.

6. =The limbs.=—How many limbs has the rabbit? Which pair is the longer? Is the difference in length an assistance in leaping? Make out the main divisions of each limb, and, by feeling through the skin, the manner of attachment of its bones to the bones of the body (Fig. 161).

7. =The tail.=—Notice the length, shape, position, and colour of the tail. The chain of bones inside it is a prolongation of the spine.

=Methods of studying animals.=—In studying animals, methods similar in principle to those described in previous chapters for plants should be employed. A real knowledge of the =habits= of animals can only be obtained by watching them as closely as possible in their natural surroundings. It is often very difficult to get sufficiently close to shy animals to see them distinctly without causing alarm, and a good field-glass is a valuable help in such cases. A great deal of first-hand knowledge of wild life can, however, be gained without such aids if the student will learn to move quietly and silently, and to remain motionless as soon as he is in a good position for observation. The books of such masters of woodcraft as Richard Jefferies, William J. Long, Ernest Thompson Seton, and W. H. Hudson give charming descriptions of the methods of tracking and studying wild animals, and should be carefully read by every field-naturalist. Observations made in the field should be at once recorded, with the date, in a note book.

Many animals can be kept for some time, without cruelty, in confinement; and a more intimate knowledge of certain of their habits can be thus obtained. The practice of keeping =pets= is, however, to be encouraged only when every possible care is taken to secure the comfort of the captives.

To understand the internal structure of an animal, =dissection= is necessary. This consists in exposing and separating the internal organs of the dead animal from each other, in order to notice their mutual relation. A careful outline drawing of every dissection should be made and preserved. The student should make it a rule never to kill _any_ animal unless for some useful purpose, and then to do so in the quickest and most painless manner.

=The habits of the rabbit.=—Wild rabbits live in =burrows= or underground passages which they excavate, by means of their strong feet, in the soil of sandbanks, fields, woods, etc. The animals are sociable, and the burrows belonging to any one community are collectively known as a =warren=. The passages of the warren communicate with the outside world by means of openings, some of which are in common use, while others seem to be used mainly as “bolt-holes” in cases of sudden alarm. A rabbit which is bolting to its burrow exposes the white underside of its tail, and thus acts as a danger signal and guide to its fellows. When a rabbit is startled, or puzzled by seeing some unusual object, it generally thumps the ground smartly with its long hind-foot; other rabbits in the neighbourhood are thereby warned.

It is common to find, outside a rabbit warren, a number of intersecting paths, perhaps nine inches wide, and worn smooth by the patter of little feet. These are the highways, or “runs,” which lead from the holes of the warren to the various feeding-grounds.

Rabbits breed very rapidly; it has been estimated that in five years a single pair might have about a million descendants, were it not for the countless mishaps to which rabbits are exposed. The young are born and suckled in a special shallow burrow, which the doe excavates and lines with dry leaves, fur, etc. When she leaves the nest for any purpose she covers up the entrance with soil.

The proportions of the parts of the body of a very young rabbit are markedly different from those of the adult. The head is relatively larger, the tail longer, and the ears shorter; while the hind limbs and fore limbs are of almost equal length. During the first six months of its life the animal gradually takes on the proportions of the adult—with small head, long ears, large hind legs with long feet, and small, upwardly-turned tail.

A rabbit is able to stand upright on its hind legs, and to maintain itself in this position for a considerable time. It thus obtains a wider view and a greater choice of food.

The great difference in the length of the fore and hind legs gives the animal a characteristic gait. “In a freely moving rabbit,” says Jefferies, “both fore-feet stop when the hinder come up—one hinder foot slightly behind the other, and rather wide apart.” Rabbits are exclusively vegetarian feeders, living on green herbs and on the tender shoots and bark of shrubs and young trees.

=The external characters of the rabbit.=—The outside of the rabbit’s body is almost entirely covered with =fur=. This consists of two kinds of hair—coarse and fine. The coarser hairs are fewer in number and longer than the fine ones, which they protect from wet. The fine hairs are extremely closely-set, and stand straight out from the skin. In a seal-skin coat only the short hairs of the fur are to be found; the longer hairs have been removed by the dressing process. The great warmth of furs is due to the air which is entangled between the fine, close hairs. It is generally the case that fur-bearing animals are exposed to either mud or wet by their method of life; in spite of this fact, while the hair of a dog soon becomes wetted by rain, and the wool of a sheep retains a great deal of dirt, furred animals are noted for keeping their coats clean and dry.

The longest hairs of the rabbit are the stiff =whiskers= which stand out from the upper lip, the cheeks, and above the eyes. They are extremely sensitive to touch, and are of great assistance to the animal in finding its way through the dark burrows.

The =colour= of the wild rabbit is greyish brown, except on the belly and under the tail, where it is white. This colour harmonises well with the surroundings, and renders the animal much less noticeable. Wild rabbits are exposed to so many enemies, that individuals which happen to be born with conspicuously coloured fur have generally but a poor chance of surviving and leaving offspring to inherit their disadvantages. There is thus in each generation a =natural selection= of the animals which are best protected, by their colour, from observation. Among tame rabbits, on the other hand, =protective colouration= is of very little importance, and one variation of colour is as likely as another to be transmitted by =heredity= to the next generation.

=The regions of the body.=—For convenience and precision in describing animals it is customary to use the words =anterior= and =posterior= to indicate the fore, or head, end, and the hind, or tail, end respectively. The belly-surface is said to be =ventral=, and the back =dorsal=.

The body of a rabbit obviously consists of head, trunk, a short tail, and four limbs. The general arrangement of the bony framework, or =skeleton=, (Fig. 161) which supports the softer parts may be felt through the skin. The skeleton consists of (1) the _skull_; (2) the spine or _vertebral column_ (generally spoken of as the backbone), placed dorsally, and reaching from the anterior end of the neck into the tail; (3) the ventral _sternum_ or breast-bone, which is connected with the vertebral column by means of curved _ribs_; (4) the bones of the two pairs of limbs, with the shoulder-and hip-bones to which they are attached. The bones will be studied in more detail in the next chapter.

The trunk is divided into two regions—an anterior =thorax=, or chest, (enclosed in the bony cage formed by the ribs, sternum, and the adjoining part of the vertebral column), and a posterior =abdomen=. The two cavities are divided from each other by a fleshy partition called the _diaphragm_.

=Organs of special sense.=—In addition to the sense of touch which is possessed by the whole surface of the body, the rabbit has organs which enable it to distinguish objects by sight, sounds, scents, and taste. Its sense of =smell= is so keen that, to be successful in snaring rabbits, “in walking to the spot selected for the snare it is best to avoid even stepping on the run, and while setting it up to stand back as far as convenient and lean forward. The grass that grows near must not be touched by the hand, which seems to impart a very strong scent. The stick that has been carried in the hand must not be allowed to fall across the run; and be careful that your handkerchief does not drop out of your pocket on or near it. If a bunch of grass grows very tall and requires parting, part it with the end (not the handle) of your stick.”[8]

The shape of the =ear-flaps=, which can be turned in different directions (Fig. 159), enables the rabbit to catch very slight sounds.

The =eyes= are placed on the _sides_ of the head, so that the animal has a wide field of view, and an enemy approaching from behind is not likely to be unnoticed. The eye of the rabbit is very similar in structure to our own, but it possesses one useful adjunct which ours has lost, in the shape of a _third eyelid_—an opaque flap of skin which lies in the inner angle, and can be drawn over the eyeball at will. The little fleshy nodule in the corresponding position of the human eye is a rudiment of a similar structure.

=The rabbit a gnawing animal.=—Rabbits are much addicted to gnawing young trees for the sake of the bark and the softer juicy tissues between bark and wood. Even tame rabbits exhibit the same instinct by gnawing their wooden hutches, although these are of no use as food. The gnawing is done by the sharp teeth, called =incisors=, which are conspicuous in the middle of both upper and lower jaw. In the upper jaw two incisors (which are so deeply grooved that they look like four) are visible even when the mouth is closed, owing to the split in the middle of the upper lip. The hardest part of the tooth (a substance called _enamel_) is at the front. Behind this the tooth is composed of a softer, bony material called _dentine_; and the back of the tooth consists of still softer dentine. The result of these differences in the composition of the various parts of the tooth is that the gnawing of hard substances wears away the back of the tooth most, the middle part next, and the front least of all; and thus a sharp chisel-edge is always maintained. Moreover, _the teeth of the rabbit never stop growing_, so that they never become appreciably shorter through use. Immediately behind the two visible incisors of the upper jaw, another and smaller pair can be felt by the finger; the enamel-faces of these are directed backwards towards the cavity of the mouth. The softer and more easily worn faces of the two pairs of upper incisors are thus in contact, and are continually worn down to form a groove. Into this groove the two incisors of the lower jaw bite. The incisor teeth stand well out from the jaws, and the split upper lip can be drawn back, so that the lips are not injured by gnawing. In the hinder part of the mouth, where the chewing, or =mastication=, of the food takes place, are six flatter but cross-ridged =grinding teeth= on each side of the upper jaw, and five on each side of the lower jaw. The insides of the cheeks are protected from sharp splinters of wood by a patch of =hair= on each side, which extends from the region of the incisors to the grinding teeth behind. The roof of the mouth is protected by hard cross-ridges, and the tongue by tough skin.

=Rodents.=—Rabbits and hares, rats and mice, and squirrels are said to be rodents (Lat. _rodo_, I gnaw), as they not only agree in the gnawing habit, but also in other very important respects.

=Mammals.=—Rodents, and all other animals which suckle their young, are included by naturalists in the class Mammalia. These animals agree further in breathing air, in having warm blood, and in being more or less completely covered with hair.

=Vertebrates.=—Mammals, birds, reptiles, amphibians, and fishes are grouped together to form the sub-kingdom Vertebrata. They are given this name because they all possess a spinal, or vertebral, column (which usually consists largely of a chain of bones), running below the dorsal surface (p. 217) of the body, from neck to tail.

=The position of the rabbit in the animal kingdom.=—It is clear from the above that the rabbit is, in the first place, a =vertebrate= animal; it belongs, secondly, to the _mammalian_ class of vertebrates, and thirdly, to the _rodent_-order of mammals.

EXERCISES ON CHAPTER XII.

1. In what respects does the hind-foot of a rabbit differ from the fore-foot? What is the use of the difference?

2. Describe the way in which a rabbit runs. What precautions does it take when feeding in an open place? (1901)

3. Make observations of the habits and external characters of hares, and compare them, point for point, with those of rabbits.

4. Describe the inside of a rabbit’s mouth, and explain the advantages of any peculiar features to be seen in it.

5. Mention the two chief constituents of a rabbit’s tooth. Describe by what means the edges of a rabbit’s incisor teeth are kept sharp.

6. Make a list of all the vertebrate animals with which you are acquainted. Why are they called vertebrates?

7. By what external characters would you recognise that an animal was a mammal?

FOOTNOTE:

[8] Jefferies, _The Amateur Poacher_ (Smith, Elder & Co.).