Wahlberg’s Epauletted Fruit Bat, Epomophorus wahlbergi
Wahlberg’s epauletted fruit bat (Epomophorus wahlbergi) is a megabat that can be found throughout southern Africa. Its range includes savannah, shrub land, and forest habitats at altitudes of up to 6,600 feet. These fruit bats have also been found in wooded urban areas, choosing to roost in manmade structures.
Wahlberg’s epauletted fruit bat can vary in color from brown to dusky brown with patches of white fur located just under its ears. Typically, females are lighter in color than males. The broad wings of these bats can grow to be between twenty to twenty-four inches in males and eighteen to twenty-one inches in females. The average weight of an adult bat can vary between 1.9–4.4 ounces. These bats are distinct from other mega bats because of the epaulette, and can be discerned from other members of its genus by noting one post dental palatal ridge.
The species is named for the epaulettes, or large pieces of hair, that form around scent glands. Only male Wahlberg’s epauletted fruit bats have these and they lift them when courting female bats. Another distinctive characteristic of these male fruit bats are air sacs located on the neck, which are thought to increase the volume of courtship calls.
Wahlberg’s epauletted fruit bat does not enter torpor, or deep sleep, instead regulating its body temperature by heterothermy. This process occurs more during colder seasons, and these bats experience the biggest seasonal temperature differences within the entire Afrotropical region. During cold seasons, these bats are able to control their core temperatures by having an increased body mass, increased metabolic rate, and by the ability of the thermoneutral zone, or range at which a creature can handle a certain temperature, to increase. This increase helps to regulate the body temperature by making up for small changes in body temperature and by decreasing the amount of energy it takes to compensate for these changes. However, some of these bats are unable to handle high temperatures, and even after panting, licking, or wing fanning they may die.
Wahlberg’s epauletted fruit bat is a nocturnal creature that prefers to roost in open trees with plenty of light. They also enjoy roosting in dense forests near water or under palm fronds, thatched roofs and sometimes in caves. Groups of up to 100 bats will roost together, and these groups will choose their roosts daily or every few days. It is thought that the roosting patterns may follow the ripening of fruit trees or to decrease predation. Typically, females will fly farther than males to feeding sites, and may fly for up to 2.5 miles to reach a site.
When roosting, these bats are well camouflaged and white fur patterns near the head make it harder to see when viewed from below a tree. In flight, Wahlberg’s epauletted fruit bat is clumsy, and may bump into objects frequently. After a flight, the bats will usually groom themselves for up to thirty minutes.
The diet of this fruit bat consists of guava, figs, and other fruits of the Diospyros species, and the food is typically carried from tree on which it was found to another tree. The soft meat of the fruit is consumed, and the seeds and skin are thrown out. These bats may also eat leaves from the Balanites species of plants as well as many insects.
During mating season, interactions between Wahlberg’s epauletted fruit bats increase, and usually only occur when roosting and parenting otherwise. The courtship ritual consists of the male flying from the roosting tree to a separate tree. Once there, they will emit a frog-like call and lift their epaulettes for up to an hour. If they are not successful in finding a mate on one tree, they will move to the next after the hour has elapsed. While making these calls at a rate between seventy-five and one hundred and twenty calls per minute, males will take care to place themselves at least one hundred and seventy-five feet away from each other.
Female Wahlberg’s epauletted fruit bats can give birth twice a year, first during the rainy months of February to March and then between October and December. Litters typically consist of one pup, but litters of up to two have been reported. Pups are weaned at approximately fifteen months. The IUCN has listed Wahlberg’s epauletted fruit bat as of “Least Concern”.
Image Caption: Wahlberg’s Epauletted Fruit Bat (Epomophorus wahlbergi), Arusha, Tanzania. Credit: D. Gordon E. Robertson/Wikipedia(CC BY-SA 3.0)