Straw-coloured fruit bat (Eidolon helvum)

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Straw-coloured fruit bat fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Straw-coloured fruit bat description

The straw-coloured fruit bat (Eidolon helvum) is the second largest bat on the African continent ^{(2) (3)}. Despite its name, this bat is not a consistent straw-yellow colour, instead ranging from pale yellow to dark brownish-grey ^{(2) (4)}. The fur on the rump and legs is often darker than on the more yellowish shoulders, and the underparts are lighter than the upperparts ⁽⁴⁾.

Adult straw-coloured fruit bats usually have a bright orange, yellow or brownish collar of longer hairs on the throat, which extends upwards onto the back of the neck ^{(2) (4)}. This collar overlies glands on the skin that secrete a musky-smelling fluid ^{(2) (4)}, and is brighter and more pronounced in males ⁽²⁾.

The female straw-coloured fruit bat is only slightly smaller than the male and often appears lighter in colour. Juvenile straw-coloured fruit bats are generally darker than the adults, and lack a collar ⁽²⁾.

The straw-coloured fruit bat has long, dark blackish-brown wings which are quite narrow and pointed. When the bat is at rest, the tips of the wings are folded inwards ^{(2) (4)}. The tail membrane is narrow, running along the insides of the thighs, while the tail itself is short and projects beyond the membrane for about half its length. The first finger on the forearm is long and has a strong, curved claw, which is used for climbing among tree branches ⁽⁴⁾.

Also known as

African straw-coloured fruit bat, straw-colored fruit bat.

Size

Total length: 15 - 19.5 cm ⁽²⁾

Wingspan: 75 - 95 cm ⁽²⁾

Forearm length: 11.7 - 13.2 cm ⁽²⁾

Weight

250 - 350 g ⁽²⁾

Straw-coloured fruit bat biology

The straw-coloured fruit bat is found in colonies which can range from thousands to millions of individuals, and within each colony clusters of up to 100 individuals are formed ^{(1) (2)}. These colonies are found in a variety of sites, ranging from tall trees to caves and rocks ⁽²⁾. The bats display considerable roost-site fidelity, meaning that colonies typically use the same roosting sites over time ⁽¹⁾.

At its daytime roost, the straw-coloured fruit bat is alert and active, with its eyes open and ears erect, and moves about continually. At night, it typically alternates between periods of feeding and resting ^{(2) (4)}. The constant noise levels in colonies of this species suggest that it relies to a great degree on vocal communication ⁽²⁾.

Mating in the straw-coloured fruit bat is seasonal, usually occurring from April to June. However, the embryo usually undergoes a process known as delayed implantation, becoming dormant until its development begins again around October. The total gestation period lasts about nine months, with the young being born around February to May ^{(2) (4)}.

The straw-coloured fruit bat usually gives birth to a single young each year ^{(2) (4)}, typically in a ‘maternity colony’ consisting of clusters of females ⁽²⁾. The young bat is carried by the female until able to fend for itself ⁽⁴⁾.

This species is a strong flier, with wings that are built for endurance rather than agility ⁽³⁾. Its flight is slow and steady ^{(2) (4)}, interspersed with short glides, and the straw-coloured fruit bat is also able to clamber around branches and cling to trees using the strong, hooked claw on its first finger ⁽⁴⁾. Like other species in the Pteropodidae family, the straw-coloured fruit bat does not use echolocation ⁽⁵⁾.

The straw-coloured fruit bat feeds on fruiting and flowering trees, starting its foraging at sunset and ending after sunrise ⁽²⁾. It feeds on a range of sweet, juicy fruits, including dates, figs and palm fruits, as well as on flowers, buds and even young leaves ^{(2) (4)}. Like other Pteropodidae species, the straw-coloured fruit bat mashes fruit between its teeth, sucking out the juices and spitting out the rest as dry pellets. This species also chews into soft wood to obtain moisture. Despite its sometimes destructive feeding habits, the straw-coloured fruit bat is an important pollinator of flowering plants ⁽²⁾.

The straw-coloured fruit bat is thought to be an opportunistic feeder, sometimes migrating over large distances to exploit increases in regional food supplies ⁽³⁾. For example, the annual influx of an estimated five to ten million straw-coloured fruit bats into Kasanka National Park, Zambia, is said to be one of the most spectacular of all fruit bat migrations ⁽³⁾. Satellite tracking studies have shown that this species is capable of migrating thousands of kilometres each year, giving it the furthest recorded migration of any African mammal ⁽⁶⁾.

Potential predators of the straw-coloured fruit bat include snakes, carnivorous birds such as owls, crows and buzzards, and mammals ⁽²⁾.

Straw-coloured fruit bat range

The straw-coloured fruit bat has a wide distribution across equatorial and sub-Saharan Africa, from Senegal in the west to Ethiopia in the east, and south to South Africa. It also occurs in the extreme southwest of the Arabian Peninsula and on several islands off the African coast, including Zanzibar and Pemba ^{(1) (2)}. The distribution of the straw-coloured fruit bat at the northern and southern extremes of its range is somewhat patchy and erratic ⁽¹⁾.

Three subspecies of straw-coloured fruit bat are sometimes recognised ^{(2) (4)}, with Eidolon helvum helvum occurring on the African mainland, Eidolon helvum dupreanum occurring in Madagascar, and Eidolon helvum sabaeum being known only from Yemen and Saudi Arabia ^{(1) (4)}. However, the populations on Madagascar are now generally considered to be a separate species, the Madagascan fruit bat (Eidolon dupreanum) ⁽¹⁾.

Straw-coloured fruit bat habitat

The straw-coloured fruit bat is an adaptable species that occurs in a wide variety of habitats. It is found primarily in moist and dry tropical rainforests, including evergreen forest, riverine and coastal forests and mangroves, as well as in moist and dry savanna and even urban areas ⁽¹⁾.

This large bat has been recorded from sea level up to elevations of about 2,000 metres ^{(1) (4)}.

Straw-coloured fruit bat status

The straw-coloured fruit bat is classified as Near Threatened (NT) on the IUCN Red List ⁽¹⁾.

Straw-coloured fruit bat threats

In general, the straw-coloured fruit bat is common, widespread and adaptable, and there are currently no major threats to this species ⁽¹⁾. However, deforestation and hunting are beginning to cause significant declines in some areas. For example, in West and Central Africa, the straw-coloured fruit bat is the most heavily harvested bat for the bushmeat trade. It is additionally harvested for medicinal use, and is considered to be a pest in some regions ⁽¹⁾.

Straw-coloured fruit bat conservation

The straw-coloured fruit bat occurs in a number of protected areas, including the large roosting colony found in Kasanka National Park, Zambia. Bringing hunting to sustainable levels is a priority for this species, and the identification and protection of roosting sites is also an important concern for its conservation ⁽¹⁾.

Only a small part of the migratory route of the Kasanka colony is currently protected ⁽⁶⁾, and a better understanding of the straw-coloured fruit bat’s migratory patterns may be needed to aid conservation efforts for this species ⁽¹⁾.

Find out more

Find out more about the straw-coloured fruit bat:

• DeFrees, S.L. and Wilson, D.E. (1988) Eidolon helvum. Mammalian Species, 312: 1-5. Available at:
  http://www.science.smith.edu/msi/pdf/i0076-3519-312-01-0001.pdf
• BBC Nature - Straw-coloured fruit bat:
  http://www.bbc.co.uk/nature/life/Straw-coloured_Fruit_Bat

More information on bat conservation:

• Bat Conservation International:
  http://www.batcon.org/
• Lubee Bat Conservancy:
  http://www.lubee.org/

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This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
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This species information was authored as part of the ARKive and Universities Scheme.

Glossary

Bushmeat

The meat derived from wildlife of African forests, or ‘bush’.

Carnivorous

Feeding on flesh.

Delayed implantation

The process of a fertilised egg remaining unattached in the uterus for a period of time, therefore delaying the start of development.

Echolocation

Detecting objects by reflected sound. Used by bats and odontocete cetaceans (toothed whales, dolphins and porpoises) for orientation and to detect and locate prey.

Evergreen forest

Forest consisting mainly of evergreen trees, which retain leaves all year round. This is in contrast to deciduous trees, which completely lose their leaves for part of the year.

Gestation

The state of being pregnant; the period from conception to birth.

Gland

An organ that makes and secretes substances used by the body.

Pollinator

An animal that in the act of visiting a plant’s flowers transfers pollen grains from the stamen (male part of a flower) to the stigma (female part of a flower) of a flowering plant. This usually leads to fertilisation, the development of seeds and, eventually, a new plant.

Subspecies

A population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.

References

1. IUCN Red List (March, 2012)
   http://www.iucnredlist.org/
2. DeFrees, S.L. and Wilson, D.E. (1988) Eidolon helvum. Mammalian Species, 312: 1-5. Available at:
   http://www.science.smith.edu/msi/pdf/i0076-3519-312-01-0001.pdf
3. Richter, H.V. and Cumming, G.S. (2006) Food availability and annual migration of the straw-colored fruit bat (Eidolon helvum). Journal of Zoology, 268(1): 35-44.
4. Skinner, J.D. and Chimimba, C.T. (2005) The Mammals of the Southern African Subregion. Third Edition. Cambridge University Press, Cambridge.
5. Heffner, R.S., Koay, G. and Heffner, H.E. (2006) Hearing in large (Eidolon helvum) and small (Cynopterus brachyotis) non-echolocating fruit bats. Hearing Research, 221: 17-25.
6. Richter, H.V. and Cumming, G.S. (2008) First application of satellite telemetry to track African straw-coloured fruit bat migration. Journal of Zoology, 275(2): 172-176.