Rousettus madagascariensis

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.

• Biogeographic Regions
• ethiopian ethiopian
  • native native

• Other Geographic Terms
• island endemic island endemic

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.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• forest forest
• rainforest rainforest

• Other Habitat Features
• agricultural agricultural
• caves

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.

• Other Physical Features
• endothermic endothermic
• bilateral symmetry bilateral symmetry

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.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

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.

• Key Reproductive Features
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• viviparous viviparous

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.

• Parental Investment
• altricial altricial
• female parental care 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.

• Key Behaviors
• troglophilic
• flies
• nocturnal nocturnal
• motile motile
• social social
• colonial colonial

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.

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.

• Communication Channels
• acoustic acoustic

• Perception Channels
• tactile tactile
• acoustic acoustic
• echolocation echolocation
• chemical chemical

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.

• Primary Diet
• herbivore herbivore
  • frugivore frugivore

• 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.

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.

• 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.

• Positive Impacts
• food 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.

• Negative Impacts
• injures humans
  • carries human disease
• causes or carries domestic animal disease causes or carries domestic animal disease

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.

Additional Links

Encyclopedia of Life

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.

References

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