Pteropus hypomelanus
variable flying fox

Pteropus hypomelanus is found in the Indo-Australian region, including the Philippines, Solomon Islands, Papua New Guinea, Trobiand, and the Woodlork Islands and west to Thailand and the Mergui Archipelago, but excluding Java and the lesser Sunda shelf islands. Variable flying foxes are also found in the Maldives and on islands along the eastern and western coastal regions of the Malay Peninsula. They are not found on the mainland Malay peninsula or on mainland India or Sri Lanka. (Jones and Kunz, 2000)

Variable flying foxes are found at elevations ranging from sea level to greater than 900 meters in the Philippines, but it is uncommon to find them in montane upland forest and submontane rainforest. However, variable flying foxes are found no higher than 100 meters above sea level in the Conflict Islands. Forested areas of small to medium sized islands and lowland and disturbed forests are the main habitat of P. hypomelanus. They can be found in broadleaf forests, coconut groves, and orchards. (Jones and Kunz, 2000; The Gale Group and Inc., 2003)

A naked dorsal tibia distinguishes P. hypomelanus from other Pteropus species. Length of forearm, overall body size, and locality generally are also useful for differentiating between members of the genus Pteropus. Variable flying foxes have a nearly four foot wingspan (1.21 m). Overall body length is 183 to 240 mm. Variable flying foxes are sexually dimorphic with males weighing 567 to 576 g and females weighing 467.5 to 472.5 g. They are distinguished from Pteropus faunulus by their larger body size, larger teeth, and shorter fur. The species P. hypomelanus has a forearm length of 121 to 150 mm and a skull length of 62.1 to 69.0 mm. The specis Pteropus dasymallus is different in its longer and denser pelage and fur on the upper surface of its dorsal tibia. The species P. hypomelanus is smaller than Pteropus alecto, Pteropus conspicillatus, Pteropus macrotis, Pteropus neohibernicus and Pteropus vampyrus. Also, a pale patch of fur on the chest of P. hypomelanus distinguishes it from P. vampyrus. Variable flying foxes differ from Pteropus pumilus in their larger size and dark brown hairs on the throat instead of pale gray. Variable flying foxes are distinguished from Dobsonia chapmani by the presence of a claw on the second digit and by having four upper and two lower incisors. (Jones and Kunz, 2000; Lubee Bat Conservancy, 2004; McNab and Armstrong, 2001)

The body of P. hypomelanus is fully furred and fur color is highly variable. The fur on the head is most commonly dark brown, but can range from light to yellowish brown. This head and mantle pelage color varies geographically, being darker in the western portions of the range and lighter in eastern portions of the range. Dorsum fur is brown to reddish brown while some subspecies have gray or silver hairs. Stomach color ranges from a golden buff to a cream buff. The hair around the eyes is generally grayish in color. The ears are covered in long, sparse hair on the front, but are nearly naked towards the back. The hair is short and dense on the forehead but becomes longer gradually from the neck to the mantle. The dorsal fur of P. hypomelanus is quite short while the ventral fur is an average length. The midline of the back attaches to the wing membranes as well as the base of the first phalanx of the second toe. (Jones and Kunz, 2000)

The cranium of P. hypomelanus is large, elongate, and robust, with well-developed postorbital processes and a bony spur on anterior surface of the zygomatic arch. There is often a well-developed sagittal crest, formed by the fusion of the temporal ridges. (Jones and Kunz, 2000)

Males have basal metabolic rates that are higher than expected, given their body size (0.627 ± 0.0216 cm3O2/g•h). Females have basal metabolic rates lower than expected, 83% of the expected value, given their body size (0.487 ± 0.0167 cm3O2/g•h)

Little is known about lifespan in variable flying foxes. Wild caught, captive variable flying foxes have been known to live 9 years. (Jones and Kunz, 2000; Lubee Bat Conservancy, 2004)

The roosting habits of P. hypomelanus vary from solitary individuals to large colonies called “camps” numbering anywhere from 10 to several hundred individuals. Often these large groups are responsible for the defoliation of their roosting trees by damage to young shoots and leaves as the flying foxes perch. Colonies are often organized into small family groups. In the Philippines group sizes of 50 to 70 have been reported, while roosting groups of 40 to 50 have been reported in Malaysia. Fighting occurs in the form of verbal threats and boxing with closed wings. In the Maldive Islands, skirmishes occur when two individuals meet while feeding and continue until one of the individuals leaves. (Allen, 1940; Jones and Kunz, 2000; Lubee Bat Conservancy, 2004; Wilson, 1997)

In hot weather, P. hypomelanus will cool itself by flapping its wings, licking its chest, and panting. During the day, they hang from branches with either one or both of their feet and also wrap their bodies with their wings. In cool weather, they completely wrap themselves to maintain body heat. Similar behavior occurs in wet and rainy weather. When variable flying foxes decide to leave their roost, they flap their wings with their feet still clenched to the tree branch until their bodies are parallel with the ground. Upon reaching this position they will finally let go of the branch and begin to fly. (Allen, 1940; Jones and Kunz, 2000; The Gale Group and Inc., 2003; Wilson, 1997)

At night, P. hypomelanus will travel from their roosting islands to feed at mainland locations, however none have been found any farther than 8 km from a known roost site. They fly about 30 m above the ground and will often seek troughs in waves when over seas to help overcome wind resistance. Variable flying foxes extend the claws on their thumbs during flight and use them to help land in a head-up position along with both feet. Upon landing, these flying foxes release their thumbs and hang from their feet. They feed either while hanging from their feet or clinging to vegetation with all four limbs. (Allen, 1940; Jones and Kunz, 2000; The Gale Group and Inc., 2003; Wilson, 1997)

Home Range

Variable flying foxes have never been found more than 8 km away from a known roosting site. (Jones and Kunz, 2000)

Variable flying foxes have keen eyesight, hearing, and sense of smell. They communicate with vocalizations, touch, visual displays, and chemical cues. They use their sense of smell and vision to navigate and locate food. (The Gale Group and Inc., 2003)

Variable flying foxes feed primarily on fruit and nectar from wild and cultivated plants. Known food sources include pawpaw fruits, mangos, jambu, bananas or plantains, figs, banyan flowers, berries of the damba tree, fruits of cultivated crops, flowers of the kapok tree, chico, coconut flowers, and fruits of the babolo tree. Food is found through a highly specialized sense of sight and smell. Variable flying foxes eat about half of their own body weight daily. (Jones and Kunz, 2000; Lubee Bat Conservancy, 2004; The Gale Group and Inc., 2003)

Variable flying foxes are hunted by humans for food. Their noisy roosting habits allow hunters to easily find them. Variable flying foxes are also often exported as a food source. (Jones and Kunz, 2000; Lubee Bat Conservancy, 2004; The Gale Group and Inc., 2003)

Variable flying foxes act as pollinators and seed dispersers, as do many other members of the genus Pteropus. About half of bat-dependent plants are used for nourishment, materials, and medicine by humans. (Nguyen et al., 2002; The Gale Group and Inc., 2003)

Variable flying foxes are considered destructive agricultural pests by orchard growers. (Jones and Kunz, 2000; The Gale Group and Inc., 2003)

Natives of the Philippines and Malaysia export these bats as food. Variable flying foxes are considered a delicacy in some parts of its range. A typical dish includes the animal in its entirety, fur, wings and innards, which is boiled in coconut milk and eaten as is. However, P. hypomelanus is protected in many areas. (Lubee Bat Conservancy, 2004; McNab and Armstrong, 2001; The Gale Group and Inc., 2003)

The most serious threat to variable flying foxes is deforestation and over hunting. Pteropus hypomelanus was placed on the Convention of International Trade in Endangered Species of Wild Fauna and Flora (CITES) list in 1989. It is not on the 2004 IUCN Red List of Threatened Species or the U.S. Federal list. (Jones and Kunz, 2000; Lubee Bat Conservancy, 2004; The Gale Group and Inc., 2003)

Names for P. hypomelanus include the island fox, Condoro Island flying fox, variable flying fox, lesser flying fox, kluang kechil, kalong kecil, memboi, and udawed, depending on geographic location. The word Pteropus comes from the Greek word pteron, meaning ‘foot’. In addition, the Greek words hypo, meaning ‘below’ or ‘underneath’, and melan, meaning ‘black’ or ‘dark’, help derive the more specific name hypomelanus. (Jones and Kunz, 2000)

It has been recently discovered that a Pasteurella-like organism has been causing cases of pneumonia in P. hypomelanus.