The Dayak fruit bat, Dyacopterus spadiceus, is a unique megabat found across Southeast Asia. This frugivorous bat draws scientific interest due to its ecological role in rainforest habitats. It is one of three recognized species within the genus Dyacopterus.
Physical Appearance and Habitat
The Dayak fruit bat is a small to medium-sized bat, weighing between 85 to 95 grams. Its fur is short, gray-brown on its back and silver-gray on its underside. The bat has a short tail, accounting for 10 to 20 percent of its body length, and its wing membranes connect to the second toe on each foot. It has a broad rostrum and a deep jaw, with large cheek teeth adapted for consuming fruit.
These bats are found on the Sunda Shelf, a region including Peninsular Malaysia, Borneo, Sumatra, western Indonesia, and the Philippines. They inhabit tropical rainforests, preferring old-growth forests for their abundant fruit resources. They forage in the sub-canopy and above the main canopy, and roost near limestone caves, rivers, and within hollow trees, particularly large fig trees.
Diet and Environmental Impact
The Dayak fruit bat is frugivorous, feeding mainly on fruits and nectar. Figs are a significant part of its diet, along with other fruits available in the high canopy. It favors fruits found in old-growth Paleotropical or montane rainforests.
Its feeding habits make it an important contributor to its ecosystem. It is a significant agent of seed dispersal in rainforest environments. By consuming fruits and depositing seeds in new locations, these bats assist in plant regeneration and spread. This process helps maintain the health and biodiversity of the rainforests they inhabit.
Distinctive Traits and Conservation
A notable characteristic of the Dayak fruit bat is male lactation. Males have enlarged mammary glands that can produce small amounts of milk. This is one of the few known natural occurrences of paternal lactation in mammals, though its exact reasons remain unclear. Theories suggest it might alleviate the lactation burden on the female or offer an evolutionary advantage, but its precise purpose is still under investigation.
The Dayak fruit bat is classified as “Near Threatened” by the IUCN Red List, with declining population numbers. The primary threat is deforestation of its natural habitat. Logging, agricultural expansion, and wildfires contribute to the loss of the old-growth forests these bats prefer. For instance, Malaysia lost significant natural land, including old-growth forests, between the 1990s and 2005, directly impacting the species.