Hibernation is a vital factor in the ability of bats to survive in temperate countries where insect availability is drastically reduced in winter. The value of hibernation in survival lies in the reduction of the bat's metabolic rate to very low levels, thus reducing their food requirements.
The selection of a site which fulfils the physiological requirements of hibernation must be important in the survival of the Greater horse-shoe bat. The present study shows that temperature is particularly important in the selection of a precise position for hibernation. The temperature required, however, varies throughout the winter.
In England this bat finds suitable conditions in caves, mines, tunnels, cellars, and house attics. All are dark where the bats are found and offer protection from predators. These considerations are not sufficient to explain the distribution of this bat in hibernation.
The present study shows that a large proportion of the population feeds outside the hibernaculum at times during the hibernation period. The evidence suggests that starvation is a cause of death. Hence it is not only the conditions inside the hibernacula which are important in the winter survival of a bat population. The environmental conditions outside may be just as vital.
The Greater horse-shoe bat is vulnerable since the bulk of its population depends upon relatively few sites. Its reproductive rate is very low and active conservation is needed in England, since populations are small. If conservation is to be successful however, both the physical conditions within hibernacula, and the environmental conditions outside will have to be satisfactory.