Rousettus aegyptiacusEgyptian rousette

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Geographic Range

Rousettus aegyptiacus is found throughout Africa south of the Sahara, in Egypt, and on the coastlines of the Arabian Peninsula (Grzimek, 2003). Egyptian rousettes are most common from latitudes 15 degrees north through 37 degrees south. However, they have been found as far as 40 degrees north in southern Turkey. They are also found on each of the Canary Islands, western North Africa, and throughout the Gulf of Guinea (Nogales et al., 2006; Nowak, 1999). (Grzimek, 2003; Nogales, et al., 2006; Nowak, 1999)

Habitat

Egyptian rousettes are found throughout Africa’s tropical rain forests, tropical deciduous forests, savanna, and Turkey’s Mediterranean scrub forests. Egyptian rousettes have been found in arid biomes; however, they prefer to remain in habitats that provide forest cover, roosting opportunities, and abundant fruit tree growth (Kwiecinski and Griffiths, 1999). (Kwiecinski and Griffiths, 1999)

  • Other Habitat Features
  • caves
  • Range elevation
    0 to 4000 m
    0.00 to 13123.36 ft

Physical Description

Egyptian rousettes are medium sized bats with dorsal pelage ranging from dark brown to medium gray. Ventral pelage in both genders is several shades lighter than dorsal coloration, with a collar of pale yellow or orange fur often seen around the neck. There is no color difference between genders; however, males have well-developed stiff hairs along the throat that are more recognizable than in females (Kwiecinski and Griffiths, 1999). Short fur completely covers the head almost to the end of the muzzle, with the exception of the forehead, where the fur is slightly longer. Ears are around the length of the muzzle, with blunt tips and dark coloration when compared to dorsal pelage. Egyptian fruit bats have large eyes adapted for twilight and night vision. Wing membranes are dark brown with short fur extending to the proximal half of the forearm. A claw is present on both the first and second digits, while all other digits have cartilage. Egyptian rousettes have five toes on both hind limbs, each with claws (Kwiecinski and Griffiths, 1999).

Males are typically larger than females with a total body length ranging from 14 to 19.2 cm, while females range from 12.1 to 16.7 cm. Adults may weigh 80 to 170 g and have a wingspan close to 60 cm. The forearm varies between 85 to 101.9 mm in males and 88.1 to 99 mm in females (Kwiecinski and Griffiths, 1999; Grzimek, 2003). (Grzimek, 2003; Kwiecinski and Griffiths, 1999)

  • Sexual Dimorphism
  • male larger
  • Range mass
    80 to 170 g
    2.82 to 5.99 oz
  • Range length
    12.1 to 19.2 cm
    4.76 to 7.56 in
  • Average wingspan
    60 cm
    23.62 in

Reproduction

Rousettus aegyptiacus is a polygamous species, with biannual breeding seasons. However, instances of monoestry have been recorded at higher latitudes (Baydemir and Albayrak, 2006; Bernard and Cumming, 1997). Egyptian rousettes observed in latitudes south of Egypt have two distinct peak breeding seasons separated by short periods. The first peak breeding season is from spring through summer, the second is fall through winter. Births occur towards the end of each breeding season (Okia, 1987). (Baydemir and Albayrak, 2006; Bernard and Cumming, 1997; Okia, 1987)

Females give birth to and raise a single pup with each breeding effort, though twins have been recorded occasionally (Korine et al., 1994). Estimated gestation length is 3.5 to 4 months, with synchronized births occurring in breeding colonies (Kwiecinski and Griffiths, 1999; Okia, 1987). Newborn bats are born with deciduous teeth and are altricial - completely naked apart from a thin layer of down along the head and back. Pups are weaned at 6 to 10 weeks with no difference in growth between sexes. Young reach full adult weight and size around 9 months old, about the same time young become independent from their mothers (Kwiecinski and Griffiths, 1999). Sexual maturity is reached on average at 15 months, however, females have been noted to be sexually mature at 5 to 7 months ("Egyptian Fruit Bat", 2006). ("Egyptian Fruit Bat", 2006; Korine, et al., 1994; Kwiecinski and Griffiths, 1999; Okia, 1987)

  • Breeding interval
    Breeding occurs twice yearly throughout most of their range, although one breeding effort per season may occur in northern latitudes.
  • Breeding season
    Breeding occurs typically from April to August and October to February
  • Range number of offspring
    1 to 2
  • Average number of offspring
    1
  • Range gestation period
    3.5 to 4 months
  • Average gestation period
    4 months
  • Range weaning age
    6 to 10 weeks
  • Range time to independence
    8 to 9 months
  • Average time to independence
    9 months
  • Range age at sexual or reproductive maturity (female)
    5 to 16 months
  • Average age at sexual or reproductive maturity (female)
    15 months
  • Range age at sexual or reproductive maturity (male)
    14 to 18 months
  • Average age at sexual or reproductive maturity (male)
    15 months

After birth Egyptian rousette pups are cared for solely by their mothers for around 9 months. They are capable of flying at 63 to 70 days after birth and stay with their mother until they have reached adult weight and size. Once mature, males leave maternity colonies to join bachelor groups, females join maternity colonies (Kwiecinski and Griffiths, 1999). (Kwiecinski and Griffiths, 1999)

  • Parental Investment
  • altricial
  • female parental care
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female

Lifespan/Longevity

The recorded maximum lifespan of Rousettus aegyptiacus is 22 years in the wild, with a maximum of 25 years in captivity for both males and females. In wild populations, average lifespan is typically 8 to 10 years due to factors such as predation, vitamin D deficiency, calcium-phosphorus imbalance, and osteoproliferation. Longevity in captive bats is also dependent on environmental temperatures and neurological impairment (Kwiecinski and Griffiths, 1999). (Kwiecinski and Griffiths, 1999)

  • Average lifespan
    Status: wild
    9 years
  • Range lifespan
    Status: captivity
    25 (high) years
  • Average lifespan
    Status: captivity
    22 years
  • Typical lifespan
    Status: wild
    8 to 10 years
  • Typical lifespan
    Status: captivity
    25 (high) years
  • Average lifespan
    Status: captivity
    22 years

Behavior

Egyptian rousettes are found in groups of various sizes, ranging from small colonies of 20 to 40 members to large colonies of 9,000. These colonies prefer to roost during the day in dark, slightly humid environments such as cave systems and ruins, though small colonies have been seen roosting in trees (Grzimek, 2003). During breeding seasons, males and females separate; males forming bachelor groups and females forming maternity colonies. Egyptian rousettes roost in close contact with other members of the colony to reduce the influence of temperature fluctuations. Close contact among members of the colony also allows communication with each other throughout the day during roosting. Egyptian rousettes are more active during the late afternoon and into the night, when grooming is more frequent (Kwiecinski and Griffiths, 1999). Individuals leave the day roost close to sunset each evening to forage, returning before sunrise. During summer months longer daylength delays emergence from the roost, suggesting a circadian rhythm synchronized to light-dark cycles. Due to the change in light intensity, Egyptian rousettes have different patterns of activity between summer and winter seasons. Summer seasons are characterized by longer feeding intervals than winter seasons, despite reduced dark periods and delayed roost emergence (Kwiecinski and Griffiths, 1999). (Grzimek, 2003; Kwiecinski and Griffiths, 1999)

Home Range

Home range varies in Rousettus aegyptiacus. This species has been noted to migrate southward in the northern regions of their geographic range and forage great distances away from day roosts. Males appear to defend territories, but their size has not been characterized (Kwiecinski and Griffiths, 1999). (Kwiecinski and Griffiths, 1999)

Communication and Perception

Egyptian rousettes are one of 3 members of the Rousettus genus to use both visual orientation and echolocation. Echolocation in this species is produced through a series of crude, short clicks of the tongue against the side of the mouth (Roberts, 1975; Holland et al., 2004). These short, impulsive-paired clicks assist in navigation in the dark. The frequency range is usually 12 to 70 kHz, with click structure and duration most similar to dolphins. This form of echolocation has evolved independently from the echolocation system used by other echolocating bats, such as vespertilionids (Roberts, 1975; Holland et al., 2004; Holland and Waters, 2007). (Holland and Waters, 2007; Holland, et al., 2004; Roberts, 1975)

Food Habits

Egyptian rousettes are frugivores, preferring to eat the pulp and juice of very ripe fruit. They typically take fruit from trees, such as lilac, mulberry, carob, sycamore, fig, and baobob (Kwiecinski and Griffiths, 1999; Korine et al., 1996; Grzimek, 2003). Egyptian rousettes consume 50 to 150% of total body mass in fruit each night. After selecting fruit, Egyptian rousettes take their fruit and roost close to the feeding tree. Only the pulp and juice is consumed; after thorough chewing, the seeds are spit out. Egyptian rousettes feed while holding the fruit close to the body, as a means of protecting the fruit from being pilfered by other bats. Stealing fruit is common, and these bats are aggressive when feeding (Kwiecinski and Griffiths, 1999). (Grzimek, 2003; Korine, et al., 1996; Kwiecinski and Griffiths, 1999)

  • Plant Foods
  • fruit

Predation

Because of their frugivorous diet, Egyptian rousettes are sometimes considered a threat to fruit crops during the growing season. Plantation owners and farmers often hunt Egyptian rousettes or hire bounty hunters during the flowering and fruiting seasons to reduce the risk of crop damage and profit loss (Fujita and Tuttle, 1991). Egyptian rousettes, like many members of the Family Pteropodidae, are hunted for meat as well. As a result roost population densities have declined (Fujita and Tuttle, 1991). Natural predators have not been described but are likely to include aerial predators, such as falcons, and cave predators, such as snakes and mustelids. Their nocturnal habits, cave roosting, flight, and cryptic coloration all help them to avoid predation. (Fujita and Tuttle, 1991)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Egyptian rousettes are pollinators of many nocturnally flowering trees throughout paleotropical forests. Due to their frugivorous diets, they not only pollinate the flowers of fruit trees but also assist as the primary agent in seed dispersal for many tree species (Fujita and Tuttle, 1991). Egyptian rousettes are carriers for both ectoparasites and endoparasites throughout their geographic range. Ectoparasites that use Egyptian rousettes as hosts include: Spinturnix lateralis, Ancystropus leleupi, Ancystropus zelebori, Ancystropus lateralis, Ancystropus zeleborii, Liponyssus glutinosus, Liponyssus longimanus, Eucampsipoda africanum, Nycteribosca africana, Brachytarsina alluaudi, Eucampsipoda hyrtlii, Nycteribosca diversa, Thaumapsylla brevicep, Nycteribia pedicularia, Nycteribia schmidlii, Eucampsipoda africana, Afrocimex leleupi, Thaumapsylla breviceps, Archaeopsylla metallescens, and Alectorobius camicasi (Kwiecinski and Griffiths, 1999). Endoparasites that are found in Rousettus aegyptiacus include the hemosporidian Plasmodium roussetti and the roundworm Nycteridocoptes rousetti. Outbreaks of rabies are also found in populations of Egyptian fruit bats (Kwiecinski and Griffiths, 1999). (Fujita and Tuttle, 1991; Kwiecinski and Griffiths, 1999)

  • Ecosystem Impact
  • disperses seeds
  • pollinates
Mutualist Species
  • common lilacs (Syringa vulgaris)
  • mulberry species (Morus)
  • loquats (Eriobotrya japonica)
  • carob (Ceratonia siliqua)
  • fig species (Ficus)
Commensal/Parasitic Species
  • streblid flies (Nycteribosca species)
  • sarcoptid mites (Nycteridocoptes rousetti)
  • malarial plasmodium (Plasmodium roussetti)
  • parasitic mites (Spinturnix lateralis)
  • parasitic mites (Ancystropus species)
  • parasitic mites (Liponyssus species)
  • parasitic flies (Eucampsipoda species)
  • bat bugs (Afrocimex leleupi)
  • fleas (Thaumapsylla breviceps)
  • fleas (Archaeopsylla metallescens)
  • parasitic mites (Alectorobius camicasi)

Economic Importance for Humans: Positive

Throughout their range, Egyptian rousettes pollinate many commercially valuable fruit trees. This species also works to disperse seeds away from the parent plant, allowing seed germination and spread in unpredictable conditions (Fujita and Tuttle, 1991; Izhaki et al., 1995). (Fujita and Tuttle, 1991; Izhaki, et al., 1995)

  • Positive Impacts
  • food
  • pollinates crops

Economic Importance for Humans: Negative

Rousettus aegyptiacus is perceived by many fruit farmers to be a pest of fruit crops grown commercially for human production throughout its range, though little evidence supports this and cases are often exaggerated (Albayrak et al., 2008). (Albayrak, et al., 2008)

Conservation Status

Rousettus aegyptiacus is considered a species of least concern by the IUCN. However, due to poaching and a negative interactions with commercial farming, there has been a decline in roosting sites (Albayrak et al., 2008). (Albayrak, et al., 2008)

Contributors

Rachel Cohen (author), Radford University, Karen Powers (editor), Radford University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

echolocation

The process by which an animal locates itself with respect to other animals and objects by emitting sound waves and sensing the pattern of the reflected sound waves.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

food

A substance that provides both nutrients and energy to a living thing.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

frugivore

an animal that mainly eats fruit

herbivore

An animal that eats mainly plants or parts of plants.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

migratory

makes seasonal movements between breeding and wintering grounds

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

2006. "Egyptian Fruit Bat" (On-line). Rosamond Gifford Zoo. Accessed April 20, 2010 at http://www.rosamondgiffordzoo.org/assets/uploads/animals/pdf/EgyptianFruitBat.pdf.

Albayrak, I., N. Asan, T. Yorulmaz. 2008. The Natural History of the Egyptian Fruit Bat, Rousettus aegyptiacus, in Turkey (Mammalia: Chiroptera). Turkish Journal of Zoology, 32: 11-18.

Baydemir, N., I. Albayrak. 2006. A Study on the Breeding Biology of Some Bat Species in Turkey (Mammalia: Chiroptera). Turkish Journal of Zoology, 30: 103-110.

Bernard, R., G. Cumming. 1997. African Bats: Evolution of Reproductive Patterns and Delays. The Quarterly Review of Biology, 72: 253-274.

Fujita, M., M. Tuttle. 1991. Flying Foxes (Chiroptera: Pteropodidae): Threatened Animals of Key Ecological and Economic Importance. Conservation Biology, 5: 455-463.

Grzimek, B. 2003. Grzimek's Animal Life Encyclopedia. Farming Hills, Michigan: Gale Virtual Library.

Holland, R., D. Waters. 2007. The Effect of Familiarity on Echolocation in the Megachiropteran Bat Rousettus aegyptiacus. Behavior, 144: 1053-1064.

Holland, R., D. Waters, J. Rayner. 2004. Echolocation Signal Structure in the Megachiropteran Bat Rousettus aegyptiacus Geoffrey 1810. The Journal of Experimental Biology, 207: 4361-4369.

Izhaki, I., C. Korine, Z. Arad. 1995. The Effect of Bat (Rousettus aegyptiacus) Dispersal on Seed Germination in Eastern Mediterranean Habitats. Oecologia, 101: 335-342.

Korine, C., Z. Arad, A. Arieli. 1996. Nitrogen and Energy Balance of the Fruit Bat Rousettus aegyptlacus on Natural Fruit Diets. Physiological Zoology, 69: 618-634.

Korine, C., I. Izhaki, D. Makin. 1994. Population Structure and Emergence Order in the Fruit-bat (Rousettus aeyyptiacus: Mammalia, Chiroptera). The Zoological Society of London, 232: 163-174.

Kwiecinski, G., T. Griffiths. 1999. Rousettus egyptiacus. Mammalian Species, 611: 1-9.

Nogales, M., J. Rodriguez-Luengo, P. Marrero. 2006. Ecological Effects and Distribution of Invasive Non-Native Mammals on the Canary Islands. Mammal Review, 36: 49-65.

Nowak, R. 1999. Walker's mammals of the world. Baltimore: John Hpkins University Press.

Okia, N. 1987. Reproductive Cycles of East African Bats. Journal of Mammalogy, 68: 138-141.

Roberts, L. 1975. Confirmation of the Echolocation Pulse Production Mechanism of Rousettus. Journal of Mammalogy, 56: 218-220.