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)
Range mass: 230 to 350 g.
Range length: 143 to 215 mm.
Range wingspan: 762 (high) mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
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.
Range elevation: sea level to 2000 m.
Habitat Regions: temperate ; tropical ; terrestrial
Terrestrial Biomes: savanna or grassland ; forest ; rainforest
Other Habitat Features: urban ; suburban ; agricultural
- Nowak, Ronald M., 1997. "Straw-colored fruit bat" (On-line). Walker's Mammals of the World Online, Version 5.1. Accessed November 25, 2003 at http://www.press.jhu.edu/books/walkers_mammals_of_the_world/chiroptera/chiroptera.pteropodidae.eidolon.html.
Habitat and Ecology
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.
Plant Foods: wood, bark, or stems; fruit
Primary Diet: herbivore (Folivore , Frugivore )
Because these bats visit flowers, they play a role in pollination. They also serve as agents in seed dispersal.
Ecosystem Impact: disperses seeds; pollinates
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.
- humans (Homo sapiens)
- flies (Cyclopodia greefi)
- owls (Strigiformes)
- eagles (Accipitridae)
- buzzards (Accipitridae)
- snakes (Serpentes)
- civets (Viverridae)
This list may not be complete but is based on published studies.
Life History and Behavior
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.
Communication Channels: tactile ; acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
The young are the result of delayed implantation. The embryonic development is 4 months before partrution with a birth weight of 45-50 grams. (Nowak, 1997)
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.
Status: captivity: 22 (high) years.
Status: wild: 15 years.
Status: captivity: 21.8 years.
Lifespan, longevity, and ageing
Information on the mating system of these animals is lacking.
Mating occurs in colonies from April to June. The reproductive cycle responds to rainfall, and allows weaning of young to proceed at the time of greatest food availability.
Pairs breed when the dry season begins. There is a delay in the implantation of the embryo in most, but not all, populations. The gestation period typically lasts 9 months, but the embryo only takes 4 months to develop. In populations without delayed implantation, births occur just 4 months after mating.
The young are born in February and March. Females give birth to a single offspring that weighs 50 grams at birth.
Breeding interval: These animals breed annually.
Breeding season: These bats breed from April to June
Range number of offspring: 1 to 2.
Average number of offspring: 1.
Average gestation period: 9 months.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); viviparous ; delayed implantation
Average birth mass: 50 g.
Average gestation period: 275 days.
Average number of offspring: 1.
The straw-colored fruit bat has female parental care, like all other mammals. The female nurses her offspring until it is ready to forage on its own. In this species, young are not able to fly at birth,and so are considered altricial. Although females give birth to their young in large colonies, there are no reports of cooperative care of young, nor of paternal involvement in care of offspring.
Parental Investment: altricial ; pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female)
Molecular Biology and Genetics
Statistics of barcoding coverage: Eidolon helvum
Public Records: 0
Specimens with Barcodes: 22
Species With Barcodes: 1
This is a very abundant and common species that has no legal protection.
US Migratory Bird Act: no special status
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: near threatened
IUCN Red List Assessment
Red List Category
Red List Criteria
- 2004Least Concern
Relevance to Humans and Ecosystems
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.
Negative Impacts: crop pest
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.
Positive Impacts: food ; pollinates crops
Straw-coloured fruit bat
The straw-coloured fruit bat (Eidolon helvum) is a large fruit bat that is the most widely distributed of all the African megabats. It is quite common throughout its area ranging from the southwestern Arabian Peninsula, across forest and savanna zones of sub-Saharan Africa and Madagascar. They have recently been classified as Near Threatened on the IUCN Red List due to a decreasing population trend. Straw-coloured fruit bats travel in massive colonies of at least 100,000 bats and sometimes massing up to 1 million. Their necks and backs are a yellowish-brown colour, while their undersides are tawny olive or brownish.
The straw-coloured fruit bat got its name from the silky yellowish or straw colour of its exterior. The wings are black, and the back hair is pale and tawny. Males are generally bright orange and females are usually yellowish. The bats have large cheeks, eyes, and ears. The average weight of these bats ranges from 8 to 12 oz (230 to 340 g) and the animals grow to 5.7 to 9 in (14 to 23 cm) in length, with wings spanning up to 30 in (76 cm). Males are generally larger than females. The bat's heart is very large, and its wings are long and tapered at the tip. The cheeks of the bat are also large and pouch-like.
The straw-coloured fruit bat is a highly social species. The bats tend to live in groups of over 100,000 and at times that number may increase to almost one million. At night the bats leave the roost in smaller groups to find food by sight and smell. They have also been seen chewing on soft wood for moisture. These bats can also pollinate flowers and disperse seeds through the forests. They are the main agents of seed dispersal for the increasingly rare and economically significant African teak tree Milicia excelsa.
Although they feed at night, straw-coloured fruit bats are not necessarily nocturnal. During the day, they will be found resting and moving among the colony. Year to year, season to season, the bats will return to the same place where they found food the previous year or season.
The diets of straw-coloured fruit bats vary depending on whether or not they are living in captivity. Wild bats usually eat bark, flowers, leaves, nectar, and fruits. In captivity, they are fed various mixes, including apples, oranges, bananas, grapes, and cantaloupe. In some zoos, they are also fed a marmoset diet.
Eidolon helvum is the most widely distributed fruit bat in Africa, and perhaps the world. It appears mainly in Africa, mostly among the sub-Saharan climates, in many forest and savanna zones, around the southwestern Arabian peninsula, and in Madagascar. It can also be found in urban areas and at altitudes up to 2,000 m (6,600 ft). It prefers tall trees for roosting.
- Arkon Zoo Information on Straw Colored Bats
- Taylor, D. A. R. et al. The role of the fruit bat, Eidolon helvum, in seed dispersal, survival, and germination in Milicia excelsa, a threatened West African hardwood. Northern Arizona University School of Forestry.
- Oregon Zoo Information on Straw Colored Bats
Mickleburgh, S., Hutson, A.M., Bergmans, W., Fahr, J. & Racey, P.A. 2008. Eidolon helvum. In: IUCN 2009. IUCN Red List of Threatened Species. Version 2009.1. www.iucnredlist.org.