Geoffroy's horseshoe bat - RHINOLOPHUS CLIVOSUS

Geoffroy's horseshoe bat is the most commonly encountered species of this particular genus in Southern Africa and may migrate to cold, damp caves to hibernate during winter, especially in temperate regions with cold winters. This is by far the commonest horseshoe bat in southern Africa. Like all other rhinolophids, Geoffroy’s horseshoe bat possesses the ability to hibernate in temperate regions in order to withstand adverse winter conditions, especially the dearth of insect prey. It survives winter months by reducing its body functions and metabolism during torpor to a bare minimum: heartbeat, for instance, can be as low as two pulses per minute. During the summer months individuals accumulate body fat, which provides the fuel for survival during winter inactivity. Hibernating bats apparently maintain the ability to monitor their environment and perceive threats, as they have been observed consistently to emerge from a hibernating state when seriously disturbed by careless observers. Repeated disturbances during hibernation are a threat to the hibernating animal: they emerge from torpor by shivering to increase body temperature and functions, a procedure that uses up an inordinate amount of fat reserves. If bats are forced out of hibernation too often, they may run out of the necessary reserves to last the winter, and consequently starve. It is therefore imperative that they are, if at all possible, not wakened. Adverse winter conditions also dictate the reproduction cycle: most southern African bats mate towards the end of summer when they are in prime condition, rather that at the end of winter when they are famished. The development of embryos is delayed by a variety of methods, so that birth, six months later, coincides with high incidences of prey during early summer. All rhinolophid bats roost from the ceiling of their sanctuaries. They tend to hang – either separated from each other by small distances or tightly huddled together – from their hindfeet. While the bat is roosting, the tail and interfemoral membrane are folded over the lower parts of the back, and the wings are tightly folded around the body. Distribution and Status Widely distributed and common in North Africa, as well as in countries along the eastern sectors of Africa such as Sudan, Ethiopia, Somalia, Kenya, Uganda and Tanzania, to as far south as Cape Town, and from there northwest to Namibia and southern Angola. Habitat Species has a side habitat tolerance, although it seems to avoid high evergreen forests. Its absence from desert areas, such as in Botswana, is probably related to the lack of suitable roosting sites such as caves and hollow trees. Field Characteristics On average only slightly smaller than Rüppell’s horseshoe bat, but there is a large overlap in size and weight. It is distinguished from Ruppell’s horseshoe bat by the size and configuration of the horseshoe segment of the nose-leaf, as well as by the brown-tipped hairs of the fur on the back. Breeding Biology One young is born annually to each female during the early summer months, normally after the first heavy rains of the season. Sounds Does not utter sounds that are audible to the human ear. Echolocates at high frequency. Food and Feeding Methods Moth and small beetle remains under feeding sites are a clear indication of food preferences. Because of their wing design and flying abilities, horseshoe bats have no difficulty in landing on the ground to pick up insects, and ca take off again without any real effort. This ability renders terrestrial insects an important food resource. Social System Highly gregarious; occurs seasonally in colonies of several thousand, in roosting sites capable of accommodating such numbers. May migrate to cold, damp caves to hibernate during winter, especially in temperate regions which experience cold winters. Individuals leave the roost after sunset to hunt solitarily, catching insects either on the wing or by hawking for larger prey from the sanctuary of night-time roosts. A very agile flier with well-developed echolocation abilities, and therefore prefers to hunt below the canopy levels of trees and shrubs. (Dr Naas Rautenbach)