Why should we care about Borneo's bats?
As well as being the cutest mammals to many a bat biologist, bats make up a large component of mammal diversity in Asian forests! Up to half the mammal species in a rainforest can be bats, which means they form a significant component of the forest ecosystem. Fruit- and nectar-eating bats act as pollinators and seed dispersers, several species of which are regarded as keystone species. Nectarivorous species in Southeast Asia, including Eonycteris spp., are also important pollinators for many commercial products including durian and petai. Also, insect-eating species regulate nocturnal insect populations and in some countries have been shown to be an important natural pest control in agricultural areas.

Together with swiftlets, bats are an essential part of cave ecosystems in Borneo, since species confined to the cave derive all their energy needs from outside. Bats often form large colonies and the guano they produce forms the foundations of a food chain that supports many cave-restricted species.

Hunting:
Although most Indonesians are Muslem and are not permitted to eat bats for religious reasons, many non-Muslem Dayak and Chinese people in Kalimantan consider bat meat a delicacy with medicinal properties. Bat meat and liver is considered the best cure for general malaise, kidney ailments and most notably asthma. The most common species hunted in Borneo is the large flying-fox (Pteropus vampyrus) , which was once prevalent in large colonies throughout the island's lowlands. While they can still be seen commuting over forest areas and villages, flying-fox populations appear considerably much smaller than those reported in the past.

Around many settlements, plantations and logging concessions these bats are mainly hunted for sport using blowpipes, catapults or kites. Where demand exists for bat meat, however, hunting is more organised and intensive, and live flying-foxes are sold in markets. Around Palangkaraya in Central Kalimantan, flying-foxes are targetted using large fishing nets hoisted up over the forest canopy. Around a hectare of forest is cleared to gain access to the nets and several hunters often work independently in one area. Most bats are sold to market traders around the city and can be bought for around Rp 5,000 (ca. US$ 0.50), with prices plummeting during peak season. Counts of catchs in 2003 revealed that hunters frequently captured over 50 individuals in an evening and within 1 month removed over 4,000 individuals from the Sebangau National Park.

One factor that may contribute to this decline is that hunting becomes much more intensive and productive during the bats' reproductive season. Most hunters interviewed recognise a definite "bat season" that coincides with the main fruiting peaks in the area. Like many other bat species in tropical regions flying-foxes in Kalimantan time lactation with fruiting peaks, so hunting during this period could severely limit a population's ability to recover.

A second factor likely to contribute to declines in Central Kalimantan is the wildfires that spread through the extensive peat-swamps each dry season. Not only do these events destroy vast areas of suitable habitat and affect fruiting cycles, but the resulting smoke blankets the lowlands for months of the year and has a significant impact on people's health. As lung ailments become more common and severe, demand for bat products can only increase.

Habitat disturbance and loss
The reduction of good quality forest cover is probably the single greatest threat to bats, and indeed most wildlife, in Borneo. While many bat species may be adaptable to an agricultural landscape, a large number of species are dependent on forests to some degree. Many insectivorous species feed on the abundance of insects in forests and rely on tree hollows for roosting. They also possess specialised wing morphology and echolocation that allow them to forage in cluttered forest, but at the expense of exploiting more open habitats created by forest disturbance or loss.

In Kalimantan unsustainable logging practices and clearance of forests for agriculture are prevalent. Forest fires are becoming much more common and widespread. They degrade existing forests and cause losses of logging revenues which means greater timber demand elsewhere. Fires have also affected much of the karst system in the Sangkulirang peninsula. Vegetation cover is now depleted in many areas leaving caves exposed to high temperatures in the dry season.

The expanding oil palm sector is probably the greatest long-term threat to Borneo's wildlife. Vast areas of natural vegetation are being cleared each year to make way for this monoculture. Many of these areas are so large there is little chance for wildlife, even bats, to disperse to other areas and persist over the long term.

Identifying conservation priorities
We still know very little about the impacts that hunting and environmental change are having on bats in southeast Asia. In fact, we still know relatively little about the distribution of species and their basic ecology. In Borneo, most of our knowledge arises from research in Sabah and Sarawak. Only recently, have we begun to learn more about the bat species present over Kalimantan.

In the IUCN Microchiroptera Action Plan, Borneo is recognised as part of a centre of generic bat diversity. However, within Borneo there are few distribution records and we have little idea which areas support the most species. The ultimate goal of this project is to collect additional distribution information for bat species over Borneo, and predict the most species diverse areas for setting conservation priorities. By doing this we have further justification for conservation activities in these areas.