Vanuatu flying fox  (Pteropus anetianus)

The Vanuatu flying fox is classified as Vulnerable (VU) on the IUCN Red List (1) and is listed on Appendix II of CITES (2).

A somewhat enigmatic and little-studied member of the genus Pteropus, the Vanuatu flying fox (Pteropus anetianus) is restricted to the Vanuatu archipelago in the South Pacific Ocean. Belonging to the Old World fruit bat family (Pteropodidae), the Vanuatu flying fox exhibits several characteristic features common to all species in this family, including large, well developed eyes and elongate, oval ears that lack a tragus (3) (4) (5).

As the family name suggests, the Old World fruit bats are adapted to a primarily fruit-based diet, with flattened back teeth and eight ridges on the palate, against which the tongue crushes food, as well as pronounced canine teeth and powerful jaws for piercing through the tough rinds of fruit. The Pteropodidae typically also have long tongues and snouts for reaching into flowers (3) (4).

Species in the genus Pteropus are commonly greyish, brown to dark brown or black, with a contrasting area of colour between the shoulders, which is often yellowish or greyish-yellow (3) (4). Often species of this genus have a noticeable odour (3). Although there is no specific information on the size of the Vanuatu flying fox, it is likely to have a wingspan of greater than 80 centimetres (4).

Seven subspecies of the Vanuatu flying fox are recognised: Pteropus anetianus anetianus, P. a. aorensis, P. a. bakeri, P. a. banksiana, P. a. eotinus, P. a. motalavae and P. a. pastoris (6).

The Vanuatu flying fox is endemic to Vanuatu, where it has been recorded from a number of islands within the archipelago (1) (6).

A primarily lowland species (1), the Vanuatu flying fox typically inhabits mangroves, swamps and tropical forests, often on small islands (3) (4). Some observations suggest that the Vanuatu flying fox may be more common on the windward side of islands (7). Most Pteropus species roost communally, usually on exposed branches of large trees that rise above the forest canopy (3) (4).

The Vanuatu flying fox spends most of the day in small, quiet colonies (1) (6). Colonies often use the same roosting site year after year, which are generally located considerable distances from the preferred feeding sites (3). The Vanuatu flying fox locates food mainly by sight and smell, feeding primarily on fruits, such as figs, breadfruit and coconuts, as well as on some flowers (1) (5) (6). Many Pteropus bats have also been observed eating insects to supplement the limited protein intake received from fruits and flowers (4) (5).

The Vanuatu flying fox feeds by biting into fruit while hovering, or by holding a branch with one foot and pressing the fruit to the chest with the other, before biting it. It often carries smaller fruits to a branch, where it may hang upside down while eating. The fruit juices are obtained by squeezing the fruit against the ridges of the mouth to crush it. The juices are then swallowed and the remaining pulp and seeds are spat out as pellets (3) (4).

Very little information is available on the specific breeding biology of the Vanuatu flying fox. Males are thought to become most sexually active between October and January, with females generally believed to have a birth peak in August and September (1) (6). As with other Pteropus species, it is likely that the female leaves the main colony after mating, forming smaller groups with other females. Generally species in this genus give birth to a single young after a gestation period of 92 and 140 days, with the exact duration varying between species. The adult female may carry the young for the first three to six weeks after birth, and lactation typically lasts around three to six months (3). Pteropus species have a particularly slow reproductive rate and are not able to reproduce until around one and a half to two years of age (4).

Flying foxes play an important role in pollination and seed dispersal for a great variety of plants. However, they are also considered to be a serious pest in some regions, and some species have been known to devastate crops overnight (3).

The two major causes of decline in fruit bat populations on Pacific Islands are habitat destruction and hunting (4). Deforestation is widespread throughout the tropics and poses a severe threat to the Vanuatu flying fox because it destroys the bats’ food and roosting sites (3) (4). Pteropus bats are an important food item for humans on Vanuatu (6), although the population of the Vanuatu flying fox does not generally appear overexploited (1). However, fruit bats are killed in increased numbers immediately following cyclones, which may lead to population declines (1) (6).

Severe cyclones, volcanic eruptions and earthquakes are regular events on Vanuatu, and are an important source of natural disturbance to the islands’ forest, sometimes affecting as much as 30 percent of the forest cover on the islands in some years (8). The effects of tropical storms and cyclones can be exacerbated by human disturbance of watersheds and the remaining forest areas, which tend to be particularly vulnerable to devastation (4) (8).

The Vanuatu flying fox is likely to be increasingly affected by climate change. The Intergovernmental Panel on Climate Change (IPCC) expects that climatic changes throughout the Pacific region will stimulate more extreme weather events, including higher temperatures, greater rainfall and increased frequency and severity of tropical cyclones (9) (10) (11). Low-lying coastal areas of islands in the Pacific are also especially vulnerable to rising sea levels, which may cause inundation, flooding and erosion to habitats throughout these areas. An average sea level rise of one metre could easily submerge low-lying islands, with devastating effects for the biodiversity, society and the economy of the region (11). 

The Vanuatu flying fox is listed on Appendix II of CITES (2), meaning that all trade in this species should be carefully monitored. It is present in the Vatthe Conservation Area (1).

Currently, the evidence suggests that although hunting and habitat destruction may have had some impact on the Vanuatu flying fox, these threats are not yet considered severe. Like many bats in the family Pteropodidae, the Vanuatu flying fox is poorly known and would benefit from surveys and research into its distribution, abundance and ecology, as well as the various threats it may face (1) (6).

Forest protection is considered to be one of the highest priorities for the protection of fruit bats. Primary forests are an especially important habitat, and the prevention of deforestation in such areas should protect many forest species, including the Vanuatu flying fox. Developing long-term conservation and land use policies aimed at the conservation of natural resources and establishment of forest reserves would benefit bats and other wildlife (6).

The Chiroptera Specialist Group considers that, wherever possible, the setting up of Protected Areas for bats should be a goal of national conservation efforts. The Specialist Group also indicates that hunting of fruit bats needs to be carefully managed, either through total bans or by designating a hunting season or maximum catch (6).

Find out more about bat conservation:

• Lubee bat conservancy:
  http://www.batconservancy.org/
• Mickleburgh, S.P., Hutson, A.M. and Racey, P.A. (1992) Old World Fruit Bats: An Action Plan for their Conservation. IUCN/SSC Chiroptera Specialist Group, Gland, Switzerland.

Find out more about climate change in the Pacific region:

• Secretariat of the Pacific Regional Environment Program - Climate change:
  http://www.sprep.org/topic/climate.htm