THE WINTER SLEEP OF ENGLISH ANIMALS.
WINTER sleep among animals is not a merely physical effect of cold, though it is closely connected with the fall of temperature. It is often said that the cold "sends them to sleep," just as warmth undoubtedly awakens them. But it would seem that in the beginning it was a half- voluntary device to meet the coming of famine. To keep warm and to go to sleep is a natural shift when weakness ensues from cold and hunger. The half-starved peasants in parts of Russia have recourse to a hibernation almost like that of animals; and when travellers are overtaken in blizzards and snow-storms the impulse to slumber is almost irresistible, but because they have no warm shelter to sleep in they die of cold even when in a state of lethargy. A dormouse would probably do the same if taken out of its neat when asleep and left in the snow. Considering the mildness of our winters and the shortness of the average time of really hard weather, the number of English animals. from mammals to the humblest molluscs, which hibernate, and do so for many months, is somewhat remarkable. Contrasting the periods of low temperature with those during which they pass their time wholly or partly in winter sleep, it is clear that the two do not in any degree correspond. Nothing but sheer love of slumber could excuse them from getting up and going about their business if cold were all they had to fear.
But in our islands, as in most other places, hibernation is a device not to avoid cold, but to escape death by famine. It is a temporary suspension of vital faculties and bodily waste during the months in which the cold might be quite endurable. But the growth of most plants has ceased, and most of the insects which depend upon vegetable food are either dead or are them- selves hibernating. The insect-feeding birds which live mainly on perfectly developed forms of insects fly away altogether. Those which live largely on the eggs and larvae of insects hidden in bark, like the tits and tree-creepers, or those which, like the wagtails, eat aquatic forms which survive to some 'extent during the winter because the temperature of running water alters slowly, can remain. But our insects and mollusca which either do not or cannot migrate, and very many of our insect-eating or. insect - and - vegetable - eating mammals, take refuge from famine in sleep.
Of our mammals the proportion wholly or partly in- sectivorous is considerable. In the first place, there are all the bats, of which the English species feed on nothing else but insects, and those winged insects entirely. There are one or two species of bat which crawl on the earth and feed on creeping things, but our bats seek their food wholly in the air. The smallest and commonest species is sometimes seen out until quite late in the autumn, for there are occasionally insects and moths flying in November. But the greater number of the bats seek secluded holes in roofs and church towers, and there, huddling together for some degree of warmth, sleep away the gnatless months in a cold lethargy. Besides the bats, we have a considerable proportion of the insect-feeding ground mammals belonging to natural orders whose food is mainly limited to such fare all the world over. The common shrew, the water shrew, and the elephant shrew are among these. Also, in a large degree, the dormouse is an insect-feeder. So is the delicate little harvest mouse and the hedgehog, who, though be is omnivorous, depends much on slugs, beetles, and larvae for his supper; and the list grows until we reach the badger, a truly gigantic creature to depend so far on insect food that when winter comes be feels obliged to retire from the world and take refuge in the universal panacea of winter lethargy. The writer of an excellent article in the Field on a tame female badger which be kept for seven years stated that it was her invariable practice to go out slug-hunting every evening, and that these and such "soft" insect food were her favourite provender. The hedgehog does exactly the same, and though the slugs which it eats are small, and almost invisible, they are rooted from under every fallen leaf by the .hedgehog's sensitive .snout. When the winter causes the snails to creep away into holes and stop up their shells till the spring, sends under- ground all the slugs, banishes the worms to a depth from which they will not emerge in a frost, and kills all the wasps and undeveloped wasp-grubs, the badger retires to bed, curls himself up, and sleeps until the blnebells begin to sprout in the woods in spring, when he comes out again, once more seeks his snails and slugs, and further satisfies his appetite by digging up hyacinth bulbs and roots. The hedgehog retires early, first collecting a good thick nest of dead leaves and moss under a hedge or in a rabbit-hole. The dormice con- vert birds' nests by pulling out the linings and making a dome to them, and the shrews disappear below ground. It is possible that the water shrews, which could find a store of aquatic larvae still surviving, may move and feed in winter. But the other shrews are never seen, nor are the harvest mice. The field mice and voles are awake, and their tracks may constantly be seen in the snow. The voles will peel young shoots and forage for the smallest atom of green all the winter through. The field mice, which make a store of nuts and kernels, clearly do not hibernate; or they would not need to store food ; but they retire mainly below ground during hard weather. Squirrels, though they doubtless spend much time in their nest in cold weather, may often be seen frisking in the snow. Their habit of making partial and sporadic collections of food elsewhere than in the nest shows that, being vegetable and nut feeders, they have no need to fear famine. Last week the squirrels were especially active in the woods. The writer watched a pair foraging on the ground for acorns under some high cover which was being driven by beaters. One squirrel which had secured a particularly fine and large acorn would not drop it, but came galloping from under the coppice wood carrying it in its mouth past one of the guns. It then rushed up a tree, transferred the nut to its hands, and chattered with rage and indignation at the intruders below it.
The hibernation of the lower creatures, whose withdrawal forces the long list of English mammals above-mentioned to forget their hunger in oblivion, is remarkable and complete. A great number die,—gnats, many butterflies and moths, flies, dragon-flies, and ephemeridae. But the proportion which hibernate is very large, though they have a singular power of total disappearance. Scarcely any one ever finds a hibernating house-fly, yet these disagreeable creatures do hibernate, and will come out when any part of a house is heated above the normal winter temperature. Many butterflies, especially the vanessas, creep away and sleep through the winter, and emerge at the first breath of spring warmth. Brimstone butterflies have been seen in the fields on exceptionally hot days in January. The bees, which are too clever to go entirely to sleep, but store food and keep themseves warm, suffer for their cleverness in some degree by going abroad on tempting winter days, and then being benumbed and unable to find their way home. The English ants hibernate, so do the queen wasps, humble-bees, earwigs, and those humble representatives of the crustacea, the woodlice, though there are certain moths which emerge from the pupa and fly by night even in the frost and snow of January. That there is a partial famine of insect life in the fresh waters of our ponds and brooks seems evident from the practice of the frogs and efts. These batrachians feed mainly on insect food of various kinds. When the waters begin to feel the touch of autumn frost there is a regular hibernation of these denizens of the water. The efts leave that element altogether, crawl out on to dry land, wriggle down into the earth between cracks, or under stacks of faggots or rubbish, and are there often disturbed when the earth is dug or the faggots removed. Frogs hibernate under water (where Gilbert White inclined to think that swallows did also), and lie in masses clasped together until the spring brings them to life. The toads retire to holes in the ground and in hollow trees for a like period ; and the snakes curl up and sleep in holes in the ground, manure heaps, and among rotten leaves. Thus winter sleep, partial or complete, is the rule, not the exception, among British animals, of which the mole, the fox, the deer, the hare, the rabbit, the rat, and the otter, which do not hibernate, are in the minority.
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