The dayak fruit bat or dyak fruit bat (''Dyacopterus spadiceus'') is a relatively rare frugivorous

megabat Megabats constitute the Family (biology), family Pteropodidae of the Order (biology), order Chiroptera. They are also called fruit bats, Old World fruit bats, or—especially the genus, genera ''Acerodon'' and ''Pteropus''—Pteropus, flyin ...

species found only on the

Sunda Shelf Geology, Geologically, the Sunda Shelf () is a south-eastern extension of the continental shelf of Mainland Southeast Asia. Major landmasses on the shelf include the Indonesia, Indonesian islands of Bali, Borneo, Java, Madura Island, Madura, an ...

of southeast Asia, specifically the

Malay Peninsula The Malay Peninsula is located in Mainland Southeast Asia. The landmass runs approximately north–south, and at its terminus, it is the southernmost point of the Asian continental mainland. The area contains Peninsular Malaysia, Southern Tha ...

south of the Isthmus of Kra, and the islands of

Borneo Borneo () is the List of islands by area, third-largest island in the world, with an area of , and population of 23,053,723 (2020 national censuses). Situated at the geographic centre of Maritime Southeast Asia, it is one of the Greater Sunda ...

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 list of islands by area, sixth-largest island in the world at 482,286.55 km2 (182,812 mi. ...

. There are three species in the genus ''

Dyacopterus ''Dyacopterus'' is a genus of megabats from south-east Asia. It contains three species, namely: *Brooks's dyak fruit bat, ''Dyacopterus brooksi'' *Dayak fruit bat The dayak fruit bat or dyak fruit bat (''Dyacopterus spadiceus'') is a relativ ...

'': ''D. spadiceus'' , ''D. brooksi'' and ''D. rickarti''. All are found in the forests of

Malaysia Malaysia is a country in Southeast Asia. Featuring the Tanjung Piai, southernmost point of continental Eurasia, it is a federation, federal constitutional monarchy consisting of States and federal territories of Malaysia, 13 states and thre ...

Thailand Thailand, officially the Kingdom of Thailand and historically known as Siam (the official name until 1939), is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. With a population of almost 66 million, it spa ...

, 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 sub-canopy 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, Kubah, Kota Samarahan and Pontianak, all on Borneo. The specimens, MTA96268 and MTA96269, that were held at Tanjungpura University, are the first record for this distinctive species in Kalimantan Barat,

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...

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 . 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 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 (biology), family Moraceae. Collectively known as fig trees or figs, they are native throughout the tropics with a few spe ...

'' tree in disturbed

peat swamp forest Peat swamp forests are tropical and subtropical moist broadleaf forests, 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 th ...

. 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 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 is an accumulation of partially Decomposition, decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, Moorland, moors, or muskegs. ''Sphagnum'' moss, also called peat moss, is one of the most ...

swamp forest. 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 are few 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 Monogamy ( ) is a relationship of two individuals in which they form a mutual and exclusive intimate partnership. Having only one partner at any one time, whether for life or serial monogamy, contrasts with various forms of non-monogamy (e.g. ...

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 few 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.

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 Bats of Borneo Mammals of Thailand Mammals of Brunei Fauna of Sumatra Mammals described in 1890 Taxa named by Oldfield Thomas