Eidolon helvum
straw-colored fruit bat

Eidolon helvum is the most widely distributed African fruit bat. It occurs in most of the subsaharan African continent in forest and savannah zones, the southwestern Arabian penninsula, and Madagascar. A good portion of southern Africa south of Zambia, Malawi, and Mozambique is used for migration purposes. (Smithers and Reay H.N., 1983)

These bats occupy a wide range of habitats, from coastal forests to dry, arid regions are used during the year. Prime habitat is tropical forests because of the abundance of food. Straw-colored fruit bats are found at elevations from sea level to 2000 m. These animals typically roost in tall trees, but have also been found in caves. There is great interaction with human communities as well. (Nowak and Ronald M., 1997; Smithers and Reay H.N., 1983)

E. helvum is not entirely straw-colored as its common name would suggest. The neck and back display this signature color while the ventral side of the body is a duller color of brown or grey.

This is one of the larger species of fruit bats. The males are slightly larger than the females. The head and body length is reported to be between 143 and 215 mm. Weights range between 230 and 350 g.

The wings are large and narrow, allowing the bat to fly long distances and not expend as much energy trying to flap them a lot. The wingspan can reach as much as 762 mm.

The head is large and pointed with large eyes and no white facial markings. (Happold, 1987)

Fifteen years is the expected life span of E. helvum. Some individuals do make it to their early twenties, and one individual is reported to have reached 21 years and ten months of age. (Nowak and Ronald M., 1997; Smithers and Reay H.N., 1983)

E. helvum is a gregarious, socially roosting species. Even though straw-colored fruit bats feed at night, they are active during the day while resting as they move about the roost. At night the colony leaves the roost in small groups to find food, which is usually in nearby forests or plantations. The diet is primarily frugivorous, although the fruit itself is not eated. Instead, these animals suck the fruit juice from the pulp, then spit the pulp out.

These bats fly in straight lines and at higher altitudes than other species of fruit bats.

The foraging range for a colony is 30 kilometers, as suggested by the typical distance between roosts. Roosts are rarely closer together than 60 kilometers.

Colonies of E. helvum can be large, with groups in migration routes reaching the half-million mark. However, most colonies are not this large. Studies have shown that colonies usually range in size between 100,000 and 1,000,000.

These bats use the same food sources from season to season. Migration occurs when food sources become low enough. The colonies do not break up into smaller sub-colonies when food scarcity happens.

One odd behavior exhibited by these bats is the chewing of soft wood. Apparently, the wood is munched up to obtain water. (Happold and D.C.D., 1987; Nowak and Ronald M., 1997)

Home Range

These bats typically forage over distances of about 30km. (Nowak and Ronald M., 1997)

Little information on communication in this species could be found. However, these animals are reported to be quite noisy. In addition to being loud eaters, they apparently chatter to one another in their roosts, indicating that some form of acoustic commmunication is employed. Because they roost in such large groups, it is likely that individuals come into physical contact frequently, and so probably use some sort of tactile communication as well. (Nowak and Ronald M., 1997)

E. helvum is frugivorous. Food is can be consumed while hanging by the phalanges of the feet. The food is eaten noisily. The juices are ingested and the fibrous material is discarded. In addition to consuming fruit juices, these animals are reported to chew up wood and bark, apparently to obtain moisture.

Foods eaten include: Borassus spp., dates, baobab flowers, Adansonia digitata, Bombax spp., Erythrina spp., mangoes, pawpaws, avocado pears, figs, passion fruit, custard apples and loquats. (Nowak and Ronald M., 1997; Smithers and Reay H.N., 1983)

Little information is available on species which prey upon these bats. Suspected predators include owls, eagles, snakes, buzzards, and civets. Humans are know to consume E. helvum in Zaire and West Africa. (Happold and D.C.D., 1987)

Because these bats visit flowers, they play a role in pollination. They also serve as agents in seed dispersal. (Mutere, 1980)

Agriculture is greatly affected by E. helvum because these bats live in large colonies that roost near their food source. They can feed heavily in plantations. It is difficult to assess the relative utility of the species as a polinator, versus its negative impact as a crop pest. (Nowak and Ronald M., 1997)

E. helvum are an important diet item for humans in some areas. Straw-colored fruit bats are also important pollinating agents for economically important trees in families Moracea and Bombacear. (Mutere, 1980; Nowak and Ronald M., 1997)

This is a very abundant and common species that has no legal protection.