The dayak fruit bat or dyak fruit bat (''Dyacopterus spadiceus'') is a relatively rare
frugivorous
A frugivore is an animal that thrives mostly on raw fruits or succulent fruit-like produce of plants such as roots, shoots, nuts and seeds. Approximately 20% of mammalian herbivores eat fruit. Frugivores are highly dependent on the abundance and ...
megabat
Megabats constitute the family Pteropodidae of the order Chiroptera (bats). They are also called fruit bats, Old World fruit bats, or—especially the genera ''Acerodon'' and ''Pteropus''—flying foxes. They are the only member of the su ...
species found only on the
Sunda Shelf
Geologically, the Sunda Shelf is a south-eastern extension of the continental shelf of Mainland Southeast Asia. Major landmasses on the shelf include the Bali, Borneo, Java, Madura, and Sumatra, as well as their surrounding smaller islands. ...
of southeast Asia, specifically the Malay Peninsula south of the Isthmus of Kra, and the islands of
Borneo
Borneo (; id, Kalimantan) is the third-largest island in the world and the largest in Asia. At the geographic centre of Maritime Southeast Asia, in relation to major Indonesian islands, it is located north of Java, west of Sulawesi, and eas ...
and
Sumatra
Sumatra is one of the Sunda Islands of western Indonesia. It is the largest island that is fully within Indonesian territory, as well as the sixth-largest island in the world at 473,481 km2 (182,812 mi.2), not including adjacent i ...
. There are three species in the genus ''Dyacopterus'': ''D. spadiceus'', ''D. brooksi'' and ''D. rickarti''. All are found in the forests of Malaysia,
Thailand
Thailand ( ), historically known as Siam () and officially the Kingdom of Thailand, is a country in Southeast Asia, located at the centre of the Indochinese Peninsula, spanning , with a population of almost 70 million. The country is bo ...
, and the Philippines. Few specimens of any of the three species exist, due not only to their rarity, but also because they rarely enter the subcanopy of the forest where they can be caught in scientists' nets.
Distribution
''D. spadiceus'' is considered a very rare fruit bat species in Peninsular Malaysia and Borneo and none in Thailand. The species were netted in four sites at
Poring
Poring is a small tourist resort in Sabah, Malaysia. Located 40 km south-east of the Kinabalu National Park Headquarters, in the district of Ranau, Poring is situated in lowland rainforest, contrasting with the montane and submontane rainfores ...
,
Kubah
''Kubah'' (literally ''Cupola'' or ''Dome'') is an Indonesian novel written by Ahmad Tohari. It follows a poor man named Karman who becomes a member of the Indonesian Communist Party, only to find himself a victim of the ongoing political stru ...
,
Kota Samarahan
Kota Samarahan, formerly known as Muara Tuang, is a town and the administrative seat of the Samarahan District in Samarahan Division, Sarawak, Malaysia. It is also a satellite town for Kuching due to its proximity to the city part of Great ...
and
Pontianak
Pontianak or Khuntien is the capital of the Indonesian province of West Kalimantan, founded first as a trading port on the island of Borneo, occupying an area of 118.31 km2 in the delta of the Kapuas River at a point where it is joined by ...
, all on Borneo. The specimens, MTA96268 and MTA96269, that were held at
Tanjungpura University
Tanjungpura University ( id, Universitas Tanjungpura) or UNTAN is a public university in the city of Pontianak in West Kalimantan, Indonesia.
Hamzah Haz, former Indonesian vice president, once taught at the university.
History
It was establishe ...
, are the first record for this distinctive species in
Kalimantan Barat
West Kalimantan ( id, Kalimantan Barat) is a province of Indonesia. It is one of five Indonesian provinces comprising Kalimantan, the Indonesian part of the island of Borneo. Its capital city is Pontianak. The province has an area of 147,307&nb ...
,
Indonesia
Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...
n Borneo. Specimens UMS0010, MTA96237, and MTA96238 from Sarawak and MTA96208 from Sabah are new additional records for the species in the sampling areas. These new sites have extended the range of ''D. spadiceus'' to the western and southern parts of Borneo.
Previous distribution records includes Selangor and Negeri Sembilan in Peninsular Malaysia, Sumatra; Sepilok and Baturong Caves in Sabah; Baram and Niah areas in Sarawak (Medway 1978, Payne et al. 1985).
Description
The dayak bat averages less than 150 grams. It is gray-brown dorsally with a silver-gray ventral side. Its fur is short. It has a short tail, ranging from ten to twenty percent of its body length. Its wing membranes attach to the second toe on each foot.
''D. spadiceus'' is the smallest of the bats in the genus ''Dyacopterus''. It has the smallest skull size, averaging less than 36.1 mm from the premaxilla to the base of the skull. It has a proportionally wide skull, however, when compared to the other bats in the genus.
Diet
The dayak bat is frugivorous, feeding on fruits from trees extending into or past the canopy of the forests of Malaysia. Figs are a staple of its diet, as are whatever fruits are seasonally available in the high canopy. ''D. spadiceus'' seems to prefer the fruits of old-growth Paleotropical rainforest, or montane rainforest. This makes them particularly susceptible to deforestation. Frugivorous bats are one of the main agents of seed dispersal in the rainforest, making them essential to the ecosystem.
Biology and ecology
A male and five female adults were mist-netted. Two females collected from Kalimantan Barat in September 1996 were in early and late pregnancy. Both bats were caught in a mist net placed near fruiting
Ficus
''Ficus'' ( or ) is a genus of about 850 species of woody trees, shrubs, vines, epiphytes and hemiepiphytes in the family Moraceae. Collectively known as fig trees or figs, they are native throughout the tropics with a few species extending in ...
tree in disturbed
peat swamp forest
Peat swamp forests are tropical moist forests where waterlogged soil prevents dead leaves and wood from fully decomposing. Over time, this creates a thick layer of acidic peat. Large areas of these forests are being logged at high rates.
Peat ...
. Females from Kota Samarahan and Kubah were lactating in September 1994 and August 1996 respectively. Two individuals were caught in the subcanopy (between 10 – 15 m ) by using a vertically-hoisted mist net placed in the
Sungai Rayu at Kubah. The individual from
Poring
Poring is a small tourist resort in Sabah, Malaysia. Located 40 km south-east of the Kinabalu National Park Headquarters, in the district of Ranau, Poring is situated in lowland rainforest, contrasting with the montane and submontane rainfores ...
was caught in the
emergent tree above the main canopy (> 30 m from the ground level). However, the two specimens from Kalimantan Barat were taken from the ground level nets in a
peat
Peat (), also known as turf (), is an accumulation of partially decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, moors, or muskegs. The peatland ecosystem covers and is the most efficien ...
swamp forest
Freshwater swamp forests, or flooded forests, are forests which are inundated with freshwater, either permanently or seasonally. They normally occur along the lower reaches of rivers and around freshwater lakes. Freshwater swamp forests are found ...
.
There is no previous information on the biology and ecology for ''D. spadiceus'' as indicated by Medway (1978), Payne et al. (1985) and Mickleburg et al., (1992).
Reproduction
As there are few samples of ''Dyacopterus spadiceus'', and no socioeconomic studies have been performed, there is little data available on the reproduction and habits of any of the ''Dyacopterus'' species. However, from information gained during studies of Malaysian fruit bats in general, ''D. spadiceus'' seems to be a monogamous species, with both sexes coming into sexual maturity when they reach 70 grams (approximately one-half adult body weight). While it is unknown how long the females gestate, females have been found carrying embryos from June to July, and have been found lactating from June until September. This would suggest a one- to two-month lactation time, after which the young is weaned and probably leaves the nest. Females have been found carrying either one or two embryos. In a study on the abundance of fruit bats in Malaysia, two fruit bats, one male, one pregnant female, were found roosting in a hollow limb of a fig tree.
Paternal lactation
The male of the ''D. spadiceus'' species is one of the known natural occurrences of
paternal lactation. While the reasons the male would lactate are currently unknown, it could be a mechanism to take some of the pressure of lactation off the female. This may confer an evolutionary advantage in lactating males over other non-lactating males.
See also
*
Mammals of Borneo
The mammal species of Borneo include 288 species of terrestrial and 91 species of marine mammals recorded within the territorial boundaries of Brunei, Indonesia and Malaysia. The terrestrial mammals are dominated by the chiroptera (102 species of ...
References
*Hall LS, Gordon G. Grigg, Craig Moritz, Besar Ketol, Isa Sait, Wahab Marni and M.T. Abdullah. 2004. Biogeography of fruit bats in Southeast Asia. Sarawak Museum Journal LX(81):191-284.
*Karim, C., A.A. Tuen and M.T. Abdullah. 2004. Mammals. Sarawak Museum Journal Special Issue No. 6. 80: 221—234.
*Mohd. Azlan J., Ibnu Maryanto, Agus P. Kartono and M.T. Abdullah. 2003 Diversity, Relative Abundance and Conservation of Chiropterans in Kayan Mentarang National Park, East Kalimantan, Indonesia. Sarawak Museum Journal 79: 251-265.
*Hall LS, Richards GC, Abdullah MT. 2002. The bats of Niah National Park, Sarawak. Sarawak Museum Journal. 78: 255-282.
*Francis, Charles M., et al.; "Lactation in Male Fruit Bats," Nature, 367:691-692, 1994.
*Fackelmann K.A., “Real males that lactate: A batty story.” Science News Vol. 145 p 148
*Hodgkisin R., S. T. Balding, A. Zubaid, T.H. Kunz, Temporal Variation in the Relative Abundance of Fruit Bat (Megachiroptera:Pteropidae) in Relation to the Availability of Food in a Lowland Malaysian Rain Forest, Biotropica Vol. 36, p. 522-533
*Helgen K.M., D. Kock, R.K. Comez, N.R. Ingle, M.H. Sinoga, Taxonomy and Natural History of the Southeast Asian Fruit-Bat Genus Dyacopterus, Journal of Mammalogy Vol. 88, p 302-318
*Ingle N.F., “Seed Dispersal by wind, birds, and bats between Philippine montane rainforest and successional vegetation” Oecologia. Vol. 134 p 95-104
*Konig B., “Cooperative Care of Young in Mammals” Naturwisenschaften. Vol. 84 p 95-104
External links
The incredible milk-producing male bat
{{Taxonbar, from=Q1765328
Dyacopterus
Bats of Southeast Asia
Bats of Indonesia
Bats of Malaysia
Mammals of Borneo
Mammals of Thailand
Mammals of Brunei
Fauna of Sumatra
Mammals described in 1890
Taxa named by Oldfield Thomas