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Rousettus madagascariensisMadagascan rousette

By Caitlin Braun

Geographic Range

Madagascan rousettes (Rousettus madagascariensis) are endemic to the island of Madagascar, off the Southeast coast of Africa. They are widespread throughout the island; however, they are rarely found in the central highlands or the arid southwest. (Andriafidison, et al., 2012; Jenkins, 2011)

Habitat

Madagascan rousettes can be found inhabiting lowland rainforests and deciduous forests where annual rainfall averages 2,000 mm per year. They can even be found in Eucalyptus plantations located near agricultural regions. They are found in lowland forests at elevations ranging from sea level to 800 meters. The habitat of these bats is dwindling. The forests have been degraded and fragmented, which puts more pressure on the remaining forests to support the increasing populations of human inhabitants. (Crowley, 2013; Nelson and Horning, 1993)

  • Range elevation
    0 to 800 m
    0.00 to 2624.67 ft

Physical Description

With forearm lengths of 66.0 to 76.2 mm, head and body lengths of 119 to 140 mm and skull lengths of 34.1 to 37.6 mm, Madagascan rousettes are the smallest of Madagascar’s three endemic fruit bats. These bats have proportionally broad wings, with wingspans ranging between 42.5 to 52 cm. Their wing membrane is attached to their foot, between the first and second toes. Like many other fruit bats, Madagascan rousettes have a rather pointed muzzle, wide spread, relatively short ears and large eyes, much like the facial features of a common dog. However, their skull is very delicate, with light zygomatic arches, a slender rostrum and no sagittal crest. Their teeth are very rousettine in form, but slightly narrower and display a palatal ridge pattern of 4 + 3 + 1. Their fur is dense and quite long, however, their fur is shorter around their neck, throat and shoulder areas. Their upperparts are grey-brown with a hint of red, while their under parts are a lighter shade of grey. Their upper arm, including the upper part of the forearm, is furred dorsally and ventrally, although the dorsal fur is very short. In comparison, their legs are almost hairless. Madagascan rousettes have a lower body mass from May to July. Lower ambient temperatures and the scarcity of food result in increasing metabolic rates that cause their body masses to decrease. (Bergmans, 1977; Bush Warriors, 2013; Jenkins and Racey, 2008; McNab, 1969)

  • Range mass
    50 to 80 g
    1.76 to 2.82 oz
  • Range length
    11.5 to 14.5 cm
    4.53 to 5.71 in
  • Range wingspan
    42.5 to 52 cm
    16.73 to 20.47 in

Reproduction

At this time, there is little known about the mating system of Madagascan rousettes. However, they may be similar to other members of their genus. Egyptian fruit bats (Rousettus aegyptiacus) have a promiscuous system of breeding, not usually associated with sexual selection, likewise, long-haired rousettes (Rousettus lanosus) also have multiple partners. Madagascan rousettes may also follow this mating system. (Hood, 2000)

The breeding of Madagascan rousettes seems to coincide with high temperatures and food availability, which occurs during the summer season in Madagascar. The particular breeding strategies of this bat are based on the local environment. The body mass of both females and males are at their lowest during May through July. However, the body mass of females is heavier in December and January (the wet season) during pregnancy and lactation. Pregnancies have been observed between October and December, with lactation and birth occurring in the early rainy season, roughly starting around December. Females carry their young in flight until about January. Starting as soon as 6 weeks after birth, female bats begin weaning their young, by 8 weeks they are fully weaned, which occurs toward the end of the wet season (March to April). After weaning, the bat’s diet consists of a high proportion of seeds. (Andrianaivoarivelo, 2012)

  • Breeding interval
    Madagascan rousettes breed once yearly.
  • Breeding season
    These bats breed from October to January.
  • Range number of offspring
    0 to 1
  • Average number of offspring
    1
  • Range weaning age
    8 (high) weeks
  • Average weaning age
    <8 weeks
  • Range time to independence
    6 (low) weeks
  • Average age at sexual or reproductive maturity (female)
    <1 years
  • Average age at sexual or reproductive maturity (male)
    <1 years

During the first six weeks of life, female bats carry their young in flight. Starting around six weeks, females begin weaning the young bats and by 8 weeks they are independent from their mothers. There is no evidence of an investment made by male bats. (Andrianaivoarivelo, 2012)

  • Parental Investment
  • altricial
  • female parental care
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • provisioning
      • female
    • protecting
      • female

Lifespan/Longevity

There are currently no studies that provide solid evidence for the lifespan of Madagascan rousettes.

Behavior

There is no research specifically stating the territorial behavior of Madagascan rousettes. However, these bats travel at least 8 km from their roost for foraging, with round trips up to 27 km. The actual distance that they travel is a function of food distribution and availability. (Andrianaivoarivelo, 2012; Jacobson and Du Plessis, 1976)

Home Range

The home range of Madagascan rousettes is strictly limited to the island of Madagascar. The island is approximately 587,045 sq km (226,658 sq mi) making it the fourth largest island in the world. (Lagasse, 2013)

Communication and Perception

Madagascan rousettes utilize echolocation to navigate their way in the dark when they are active and foraging. Echolocation in this genus is described as a series of short clicks of the tongue against the side of the mouth. The echo is used by measuring the time delay between the click sound produced by the bat and any echoes that may return from obstacles in the environment, the bat is then able to navigate around the obstacles. (Jones and Teeling, 2006; Roberts, 1975)

Food Habits

Madagascan rousettes feeds mainly on juices of fruits, soft fruit pulp and nectar including Ficus, banana nectar, litchis (Litchis chinensis), and jamba (Syzygium). Seeds are rarely found in the diet of these bats, with the exception of the small seeds of Ficus rubra fruits. These bats seek out fruit species that are particularly rich in calcium, lipids and have a high moisture content. When other species are available, they do not show a preference for commercially important fruits. Madagascan rousettes frequently carry their food in their mouths away from the foraging trees. (Andrianaivoarivelo, 2012; Jenkins, 2011)

  • Plant Foods
  • fruit
  • nectar

Predation

Few known predators effect the population of Madagascan rousettes more than humans. In Madagascar, these bats are hunted and killed as bushmeat. They are legally hunted between the months of May and August; however, there are incidents throughout the year of illegal hunting. Their only other documented predator is barn owls (Tyto alba) in western Madagascar. (Durbin, 2007; Goodman and Griffiths, 2006; Jenkins and Racey, 2008)

Ecosystem Roles

The extent to which Madagascan rousettes act as seed dispersers and pollinators remains to be described. Their potential for seed dispersal is clear because of their small size; they are the only fruit bat in Madagascar that can fly within intact forests, allowing them to transport and defecate viable seeds. (Andrianaivoarivelo, 2012; Jenkins, 2011)

  • Ecosystem Impact
  • disperses seeds
  • pollinates

Economic Importance for Humans: Positive

This bat is hunted as a source of protein. It is also the subject of intense scientific studies. (Jenkins, 2011)

  • Positive Impacts
  • food
  • research and education
  • pollinates crops

Economic Importance for Humans: Negative

By itself this bat does not pose any threat to humans. However, there is conclusive evidence that Madagascan rousettes have come in contact with a virus from the genus Henipavirus. These bats may have contracted it by sharing cave roosts with other species that carried the virus. The emergence of this virus represents a health problem for humans and animals; it causes severe febrile encephalitis, which has been associated with death in humans and respiratory illnesses in domestic pigs and horses. (Iehlé, et al., 2007)

Conservation Status

Madagascan rousettes are listed as 'near threatened' under the Red List classification. They are listed as such because they have experienced a population decline of 20 to 25% over the past 15 years, however, they are not declining fast enough to be placed under a higher threat category. They were considered 'vulnerable' in 1996. As a game species under Malagasy law, Madagascan rousettes are only protected in nature reserves. There are 6 reserves where these bats occur: Réserve Spéciale d’Ankarana, Réserve Spéciale d’Analamerana, Parc National d’Ankarafantsika, Parc National de Namoroka, Parc National du Tsingy de Bemaraha and Parc National d’Isalo. (Andriafidison, et al., 2012; Goodman, et al., 2005)

Contributors

Caitlin Braun (author), University of Wisconsin-Stevens Point, Christopher Yahnke (editor), University of Wisconsin-Stevens Point, Leila Siciliano Martina (editor), Animal Diversity Web Staff.

Glossary

Ethiopian

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

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

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.

causes or carries domestic animal disease

either directly causes, or indirectly transmits, a disease to a domestic animal

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.

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.

island endemic

animals that live only on an island or set of islands.

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.

seasonal breeding

breeding is confined to a particular season

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.

tropical

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

viviparous

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

References

Andriafidison, D., S. Cardiff, S. Goodman, A. Hutson, R. Jenkins, A. Kofoky, P. Racey, J. Ranivo, F. Ratrimomanarivo, H. Razafimanahaka. 2012. "Rousettus madagascariensis" (On-line). IUCN Red List of Threatened Species. Accessed April 25, 2013 at www.iucnredlist.org.

Andrianaivoarivelo, R. 2012. "Universite D'Antananorivo" (On-line pdf). Accessed May 02, 2013 at http://hal-sde.archives-ouvertes.fr/docs/00/70/06/78/PDF/ThA_se_Radosoa_A._Andrianaivoarivelo_2012.pdf.

Bergmans, W. 1977. Notes on new material of Rousettus madagascariensis Grandidier, 1929 (Mammalia, Megachiroptera). Mammalia, 41/1: 67-74.

Bush Warriors, 2013. "IUCN Species of the Day: Madagascan rousette" (On-line). Accessed April 20, 2013 at http://bushwarriors.org/.

Crowley, H. 2013. "Eastern Madagascar" (On-line). World Wildlife Fund. Accessed April 15, 2013 at http://worldwildlife.org/ecoregions/at0117.

Durbin, J. 2007. New legislation for the protection of Malagasy species. Lemur News, 11: 4-6.

Goodman, S., D. Andriafidison, R. Andrianaivoarivelo, S. Cardiff, E. Ifticene, R. Jenkins, A. Kofoky, T. Mbohoahy, D. Rakotondrayony, J. Ranivo, F. Ratrimomanarivo, J. Razaflmanahaka, P. Racey. 2005. The distribution and conservation of bats in the dry regions of Madagascar. Animal Conservation, 8: 153-165.

Goodman, S., O. Griffiths. 2006. A case of exceptionally high predation levels of Rousettus madagascariensis by Tyto alba (Aves: Tytonidae) in western Madagascar. Acta Chiropterologica, 8: 553-556.

Hood, C. 2000. Geometric morphometric approaches to the study of sexual size dimorphism in mammals. Hystrix the Italian Journal of Mammology, 11/1: 77-90.

Iehlé, C., G. Razafitrimo, J. Razainirina, N. Andriaholinirina, S. Goodman, C. Faure, M. Georges-Courbot, D. Rousset, J. Reynes. 2007. Henipavirus and Tioman Virus Antibodies in Pteropodid Bats, Madagascar. Emerging Infectious Diseases, 13/1: 159-161.

Jacobson, N., E. Du Plessis. 1976. Observation of the ecology and biology of the Cape Fruit Bat Rousettus aegyptiacus leachi in the eastern Transvaal. South African Journal of Science, 72: 270-273.

Jenkins, D. 2011. "Madagascan rousette fact file" (On-line). Arkive. Accessed April 21, 2013 at http://www.arkive.org/madagascan-rousette/rousettus-madagascariensis/image-G47576.html.

Jenkins, R., P. Racey. 2008. Bats as bushmeat in Madagascar. Madagascar Conservation & Development, 3/1: 22-30.

Jones, G., E. Teeling. 2006. The evolution of echolocation in bats. Trends in Ecology and Evolution, 21/3: 149-156.

Lagasse, P. 2013. Madagascar. Pp. 1-3 in P Legasse, ed. The Columbia encyclopedia, Vol. 6, 6 Edition. Columbia Electronic Encyclopedia: Columbia University Press.

McNab, B. 1969. The economics of temperature regulation in Neotropical bats. Comparative Biochemisty and Physiology, 31: 227-268.

Nelson, R., N. Horning. 1993. AVHRR-LAC estimates of forest area in Madagascar, 1990. International Journal of Remote Sensing, 14/8: 1463-1475.

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

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