Our Bats are all nocturnal in their habits, though a few indulge in occasional flights by day. Most of them have definite hours for flight, the time depending upon the flight period of the insects they prey upon particularly. They retire for the day into dark situations, such as hollow trees, caves, outhouses, or under roofs. In these sleeping places great numbers often congregate, and several species may be represented. During bad weather—when, of course, their insect prey also remains under cover—they do not leave their daytime shelter. When asleep their body temperature falls considerably. In harmony with this nocturnal habit we find that our Bats are usually dull coloured—some tint of brown with the underside lighter than the upper.
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.
[Pl. 14.]][C 32.
Greater Horse-shoe Bat (Rhinolophus ferrum-equinum).
Asleep in cave.
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[Pl. 15.]]
Greater Horse-shoe Bat.
Head enlarged, to show remarkable nose-leaf.
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