After rodents, bats are the most numerous mammals on earth. Like most fruit bats, the straw-colored fruit bat is rather large (insectivorous bats are generally smaller). Its wings are long and tapered to a pointed tip. Males have a bright orange ruff and wings are black, which contrast with the tawny body fur. Bats are very agile even on land, scuttling quickly over objects and squeezing themselves through small openings.
The hundreds of species reflect how bats have evolved. In East Africa there are fruit bats, hammer-headed bats, sheath-tailed bats, hollow-faced bats, epauletted bats, horseshoe bats, leaf-nosed bats, butterfly bats, mouse-eared bats, mouse-tailed bats the list goes on and on.
African bats fall into two major categories large fruit bats and smaller, insect-eating bats, none of which attack people.
Besides the difference in size between the two types, there is a great variation in the extent and details of the wings, which are formed by the naked membrane of skin that extends from the neck to the wrist and between the fingers, and finally to the tail. Wing shapes vary from species to species usually the swift fliers have long, narrow wings while the slow fliers have broad, rounded ones.
The bones of the hand that support the wing membrane are unusually long. The hind legs are rotated 180 degrees at the hip joint so that the knee flexes backward rather than forward. This arrangement does not hamper the bat when it is perched but does help it push off from the roost for a quick getaway. Bats are very agile even on land, scuttling quickly over objects and squeezing themselves through small openings.
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Bats are primarily found in forests and savannas. Colonies of bats roost together in tall trees.
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With few exceptions, bats are nocturnal and emerge from their daytime roosts only when the light of day is fading. During the day fruit bats often roost hanging upside down in the exposed branches of trees. Other species also prefer to roost upside down in large colonies that may number in the millions in dark caves, or in smaller groups in crevices, hollow trees and around houses.
Fruit bats have an acute sense of smell and large eyes that give them good night vision, both of which help them locate fruit and nectar. Insect-eating bats find their way in total darkness by emitting high-pitched squeaks through the nose or mouth as they fly. These sounds bounce off objects and echo back to the bats' ears. This echolocation, or bat sonar, allows them to locate, capture and eat insects in midair while still detecting and avoiding objects as fine as a human hair. However, in order to send and receive these location signals, they have developed strange-looking ears and noses.
Usually one bat is born a year to an adult female, which nurses the young for up to 4 months on her very rich milk. In some species, the young is carried around by the mother for 5 or 6 weeks, but in others the mothers leave them in "nurseries" while they go out to feed. The young are carried by attaching themselves to a teat or to a "false teat" (a teatlike appendage) or using their feet to hang on to the hair on the mother's stomach. Even though a young bat is two-thirds grown at 6 weeks it will not become sexually mature until 2 years of age.
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The straw-colored fruit bat, of course, feeds largely on fruit. It has large cheek pouches that enable it to take food to be eaten at another perch, away from disturbances. This is advantageous to a species that lives in very large groups that often feed together.
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In some parts of Africa straw-colored fruit bats are considered a delicacy. Elsewhere they are considered pests and killed to prevent the destruction of fruit crops. Studies, however, have shown that bats only eat very ripe and unmarketable fruit and may even help reduce fungi and fruit flies in commercial plantations. Bats are also slaughtered because of superstitions and the musky odors and noise emanating from their roosting places. The rapidly declining numbers of certain fruit bats is of concern to scientists who feel that bats are being eliminated before their role in the balance of nature is fully understood.
Did You Know?
- Bats, like most wild animals, will bite if handled, but if left alone they normally will avoid contact.
- Bats are versatile. The insect-eating type is a natural pesticide. Bat excrement, called guano, is sold as fertilizer. And seed dispersal and pollination activities of certain bats help tropical forests survive.
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