All the British species hibernate, and before the beginning of this period they develop a good deal of fat to carry them through it. On any day in the winter when there is any considerable rise of temperature they wake at once and look around for insects that have been aroused by the same means. The larger kinds usually eat their food as they fly, but the smaller Bats rest for a few moments for this purpose. The web between the legs and tail ("interfemoral pouch") is mostly used to hold their prey whilst it is being eaten. It also serves to receive the newly born young. [Illustration: _Pl. 14._ _C 32._ *Greater Horse-shoe Bat* (_Rhinolophus ferrum-equinum_) asleep in cave.] [Illustration: _Pl. 15._ *Greater Horse-shoe Bat*. Head enlarged, to show remarkable nose-leaf.] [Illustration: _Pl. 16._ *Whiskered Bat.* Myotis mystacinus.] [Illustration: _Pl. 17._ _D 33._ *Lesser Horse-shoe Bat.* Rhinolophus hipposideros.] The young Bat is born blind, but not quite naked. It at once clings to its mother's fur by means of its claws, and by its teeth to her nipple. Nursing mothers appear to form colonies apart from the others. The growth of the young Bat is rapid and it is soon fully covered with fur. Before it is a fortnight old it is able to leave its mother temporarily, but it does not lead an independent life until it is about two months old. Nothing certain is known about the age to which a Bat attains, but it appears to be about four years. Until the present century there was an astonishing lack of knowledge of the life-histories of our native species; but a small but enthusiastic band of observers have in recent years done much to make good the deficiency. In this connection the work of Messrs. Alcock, Coward, Moffat, Oldham, Tomes and Whitaker calls for acknowledgment. They have hunted far and wide, exploring the sleeping places and hibernacula, in woods, caves, roofs and belfries, and have established--among other facts--that our Bats are more numerous in the south, becoming scarcer as we go west, and that there are few species represented in the fauna of Scotland. Most of the species appear to be common in some one or more localities, even if rare elsewhere; and the physical features of a district have a striking influence on their local abundance or scarcity, certain species being more discriminative in this respect than others. The presence of woods, water, and caves appears to be the most favourable condition governing their comparative plentifulness or scarcity.