Biology
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The Madagascan rousette feeds mainly on the juices of fruits, soft fruit pulp and nectar, and may play an important role in the forest as a pollinator and seed disperser (1) (2) (5), particularly as its small size makes it the only fruit bat in Madagascar that can fly within intact forest (1) (3). The rudimentary echolocation is likely to be used only for orientation, with food being detected using vision and scent. The Madagascan rousette may fly considerable distances each night in search of food (2).
This species may form roosts of up to several hundred individuals (2), although a single cave roost of over 5,000 has also been recorded (8). During the daytime, roosts are noisy and the bats often restless, continually competing for the best positions, and fights are not uncommon (2) (5). In general, Rousettus species have extended breeding seasons which follow the rains, sometimes with two peaks each year (5). Usually, a single young is born, or occasionally twins, after a gestation period of around four months (2).
Conservation
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The Madagascan rousette occurs in several protected areas within Madagascar, including Ankarana Special Reserve and Tsingy de Bemaraha National Park (1) (6) (11). However, roost sites are in need of more effective protection both within and outside of these areas, and cooperation with local communities is likely to be vital (1) (9). Other recommended conservation actions include further study into the species' biology and ecology, especially its reproductive behaviour (6). A number of organisations have already been active in investigating the diet and foraging behaviour of the Madagascan rousette, as well as investigating the patterns and impacts of hunting, and initiating various environmental education programmes to increase awareness of bat conservation amongst local communities (3) (10). However, unless the Madagascan rousette can be effectively protected against overhunting and the effects of habitat loss, it may become increasingly threatened in the future.
Description
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The Madagascan rousette is the smallest of Madagascar's three endemic fruit bats (3). The body is greyish-brown on the upperparts, with reddish-brown tinges, and paler grey-brown on the underparts. The fur is quite long and dense, though shorter on the neck, throat and shoulders, and the wings are relatively broad (2). Like other fruit bats, the face is rather dog-like, with a pointed muzzle, large eyes, and fairly conspicuous, widely separated ears (2) (4). Although most fruit bats rely on sight and smell as their main senses, some members of the genus Rousettus also use a rudimentary form of echolocation, producing high-pitched clicks with the tongue to help detect obstacles in their path. The association of the Madagascan rousette with cave roost sites suggests that this species is also likely to possess this ability (2) (4) (5).
Habitat
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Typically inhabiting lowland rainforest and deciduous forest (2) (5) (6), the Madagascan rousette has also been recorded in Eucalyptus plantations, in agricultural areas and in villages (1) (7). Although it may roost in large trees and in tree holes, this bat prefers roosting sites in caves, and so may be largely restricted to areas where suitable caves are present (1) (2) (6).
Range
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The Madagascan rousette is endemic to Madagascar, where it widespread, although rare or absent from the central highlands and the arid southwest (1) (2).
Status
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Classified as Near Threatened (NT) on the IUCN Red List (1).
Threats
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The Madagascan rousette is believed to have undergone a decline of around 20 to 25 percent in recent decades, and, although often the most commonly trapped species during scientific surveys, is seriously threatened by overhunting (1) (3) (6) (9). Most hunting occurs at the roosts, by local people, with the bats caught in locally made traps or knocked down from the cave ceiling using sticks (1) (9). The Madagascan rousette may also potentially be killed as a pest of fruit crops (1). Under Malagasy law, the Madagascan rousette is a game species, and as such only receives protection where it occurs in nature reserves, or where it roosts at sacred sites (1) (10). However, many reserves receive little real protection, and the national hunting season for bats is also largely ignored (6) (9). Since fruit bats produce only a single offspring each year, they are particularly susceptible to overhunting (9). Forest destruction and degradation are likely to compound these problems (1) (6), although the extent to which the Madagascan rousette is impacted by deforestation is not yet fully understood (1).
Madagascan rousette
provided by wikipedia EN
The Madagascan rousette (Rousettus madagascariensis) or Madagascar rousette, is a species of megabat in the family Pteropodidae endemic to Madagascar. Its natural habitat is subtropical or tropical dry forests.
Description
The Madagascan rousette is a small fruit bat, the smallest of the three fruit bats endemic to Madagascar. The upper part of their bodies have a greyish fur while the underparts have a paler grey tinge. Like many other fruit bats, Madagascan rousettes have very dog-like faces with long, pointed snouts, large, wide eyes and largely separated ears. Like some other members of the genus Rousettus, these bats reside within cave roosts, suggesting the use of echolocation.[2] These bats are a part of a larger group of fruit bats within Rousettus which consists of 10 different species. The Madagascan rousette primarily resides on western islands of the Indian Ocean.[3]
Ecology
Habitat
The habitat of the Madagascan rousette is generally found to be associated with forests. They will roost well beyond the time of twilight. Many roosts have been found within caves however some bats have been found without a known cave roost, suggesting that the Madagascan rousette may sometimes roost within tree holes or other alternatives. They are observed to be highly mobile within a forest environment. This suggests that these bats could serve a role as pollinators and disperse seeds. The details of their diets are unknown but they have been observed to feed on introduced fruit as well as the fruits and nectar of endemic trees.[1] They have also been found to primarily forage within eucalyptus forests.[4]
Disease ecology
Members of the family Pteropodidae have been known to be natural hosts for many different types of viruses emerging within and near the Indian Ocean. Madagascan rousettes have been assayed and found to have antibodies against viruses similar to Hendra, Nipah, and Tioman, suggesting that these viruses have circulated around Madagascar in the past. The Nipa virus is known to be harmful to humans, causing fevers and other symptoms potentially associated with death. These viruses are associated with the Paramyxoviridae family. These findings represent a potential health concern as Madagascan rousettes are commonly hunted and consumed by humans. However, further studies are needed to determine the extent of these risks.[5]
Threats
Though deforestation does occur in the habitat of Madagascan rousettes, it is not well understood how this affects the species. A number of roosting colonies have been observed some distance from forests. More research is needed to clarify the extent to which deforestation affects them. However, efforts to preserve Madagascan rousettes have been made by local laws protecting them and their roosts within nature reserves.[1]
Though not completely understood, Madagascan rousettes have been found in large quantities within the regurgitated pellets of Tyto alba, a type of barn owl native to Madagascar. A study conducted at Antonibe found that roughly four-fifths of the owl's diet consisted of adult rousettes. Previous studies have shown that T. alba does not always prey on large-bodied bats and also shown that they can shift their feeding habits based on food availability. One theory of why T. alba feeds mostly on adults is that the owl preferentially hunts the larger-bodied variant of the bat. Another theory is that the rousettes are not always available as a food resource due to nursing colonies within the bat populations. This theory would also explain the irregular predation of the rousettes.[6]
Tourism is common within the Ankarana National Park where many Madagascan rousettes make day roosts. Evidence has suggested that human disturbances may affect behavior such as increasing alertness and increasing flight times. Research has been conducted examining the effects of approaching the colonies and shining light to better understand what the effects of tourism may be. The greatest effect on the bat was with a 5m-6m approach with light shining directly on the bats. The smallest effect was with a 12m-14m approach with light not directly being shone on the colonies. Colonies that did not see many tourists were significantly more reactive even at the 12m-14m range with light not being shone directly on the colonies. This suggests that rousettes become more desensitized to human visitations the more frequently it occurs.[7]
References
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^ a b c Andrianaivoarivelo, R.; Andriafidison, D.; Razafimanahaka, J. (2019). "Rousettus madagascariensis". IUCN Red List of Threatened Species. 2019: e.T19750A22002909. doi:10.2305/IUCN.UK.2019-3.RLTS.T19750A22002909.en. Retrieved 13 November 2021.
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^ "Descriptions and articles about the Madagascan rousette (Rousettus madagascariensis) - Encyclopedia of Life". Encyclopedia of Life. Retrieved 2015-11-21.
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^ Goodman, Steven M.; Chan, Lauren M.; Nowak, Michael D.; Yoder, Anne D. (2010-06-16). "Phylogeny and biogeography of western Indian Ocean Rousettus (Chiroptera: Pteropodidae)". Journal of Mammalogy. 91 (3): 593–606. doi:10.1644/09-MAMM-A-283.1. ISSN 0022-2372. PMC 7108659. PMID 32287379.
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^ Habitat use and conservation of bats in rainforest and adjacent human-modified habitats in eastern Madagascar, BioOne
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^ Iehlé, C; Razafitrimo, G; Razainirina, J; et al. (January 2007). "Henipavirus and Tioman virus antibodies in pteropodid bats, Madagascar". Emerging Infect. Dis. 13 (1): 159–61. doi:10.3201/eid1301.060791. PMC 2725826. PMID 17370536.
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^ Goodman, Steven M.; Griffiths, Owen (2006). "A case of exceptionally high predation levels of Rousettus madagascariensis by Tyto alba (Aves: Tytonidae) in western Madagascar". Acta Chiropterologica. 8 (2): 553–556. doi:10.3161/1733-5329(2006)8[553:acoehp]2.0.co;2. S2CID 86066454.
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^ The Effect of Tourist Visits on the Behavior of Rousettus madagascariensis (Chiroptera: Pteropodidae) in the Caves of Ankarana, Northern Madagascar, BioOne
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Madagascan rousette: Brief Summary
provided by wikipedia EN
The Madagascan rousette (Rousettus madagascariensis) or Madagascar rousette, is a species of megabat in the family Pteropodidae endemic to Madagascar. Its natural habitat is subtropical or tropical dry forests.
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