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Species Name: Zanzibar Pemba Flying Fox (Pteropus voeltzkowi)
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It is a large, acute-eared bat, golden-red in colour on the back and upper surface of the membrane, paler underneath. The length of the ear is approximately 35.2mm. The span is up to 1 meter, and the weight can range from 400g-650g. The sexes are alike. This species is different from the other Pteropus species on the islands by its larger size and darker, redder appearance. P. livingstonii closely resembles P. voeltzkowi in appearance but can be distinguished by its smaller size. P. rufus was formally recognized as a sub-species of P. livingstonii, and its status is currently under review. It is believed that these two species share a recent common ancestor and thus several characteristics, such as the form of the skull. P. livingstonii has often been subject to the incorrect title of Pteropus medius. It can interbreed with P. voeltzkowi, and it is suspected that the large-eared Pteropus may be a hybrid between the two species. There are several dialectal names for this species, including ‘popo mwezi gichaa’ borrowed from the Swahili name for the so-called Insanity Fruit, ‘flying fox of the month of insanity’ – a term of the Pemban dialect. Pemba flying foxes are called ‘popo wa Pemba’.
The Zanzibar Pemba flying fox is a spectacular animal and has an appearance which is most un-bat like. It is a large bat with a golden red-brown mantle, often likened to the colour of a fox, and a contrasting mantle of black hair. The head is fox-like with small rounded ears and large eyes, and the wings are long and narrow, well adapted for flight. The flying fox is sexually dimorphic i.e. the female is a lot larger than the male.
In Zanzibar it is sympatric with the small, insectivorous, and much smaller and also endemic Livingstone’s fruit bat (Pteropus livingstonii). These two species can be easily confused in the field when flying and roosting together. Pemba Flying Fox is a largely frugivorous species which eats a range of cultivated fruits as well as those of the primary and coconut tree. They can cause considerable damage to the orchard fruits and in some areas they are persecuted for this. Although reported in small numbers at forest edges, and in villages and towns, colonies of Pemba flying fox roost in large old trees in areas of tall secondary forest close to sources of permanent water. This species is in decline due to both ongoing hunting and habitat destruction, and its restricted to the southern third of the island. The hunting, capture, export and sale of the Zanzibar Pemba flying fox is now totally protected under the Zanzibar law and by the campaign of the Commission for Ecosystem Conservation and the NGOs, though it still continues at a minor level.
This species’ remarkable adaptations for flight and a lifestyle high in the forest canopy make it unique among the Pteropodids and it is the only member of the genus Pteropus to inhabit a forest environment. Interestingly, it has a wing structure somewhat similar to that of birds. Wing shape in bats is related to foraging strategy, with high aspect ratio wings (long and narrow) suiting bats that forage in more open environments and require faster, more manoeuvrable flight, while low aspect ratio wings (broader) are adapted to relatively slow flight in more cluttered environments. The Fox has the lowest wing loading (ratio of body mass to wing area) of any flying fox species, which means it requires little airspeed to stay aloft. Importantly, it is able to achieve this without compromising the loading on the wing, which is often correlated with manoeuvrability. This is ideal for a species that forages in dense forest where manoeuvrability is essential, and it also has a relatively slow wing beat. Studies of wing morphology in relation to flight have shown that the outer component of the wing, which is most used during manoeuvres, has the lowest loading, and it has been noted in previous web postings that the slender delicate nature of the Fox’s wings is often unsuited to its robust foraging behaviour, resulting in considerable wear and tear on the wing membranes. This is also reflected in the thumbs being disproportionately large and the longer claws on the hind legs compared to other flying fox species, indicating a greater degree of grappling whilst moving through the vegetation.
Jozani Forest is the best place to see this species. It is the only park on Zanzibar and is easily accessible by tourists. Jozani is the last remaining natural forest on Zanzibar and holds a large number of animals, both those introduced and those remaining from the original forest cover. The Zanzibar Wildlife and Conservation Company is conducting an environmental impact and feasibility study on the West Coast of Unguja in order to have a second protected area for the flying fox and other species. This could be a good spot to see the bat in the future.
Best time to go is 18:00 hrs when the bats first begin leaving their roost trees. The best season to see the bats is when fruit is in low abundance from September to February. During this time, bats are more likely to be seen foraging on cultivated fruit trees. Dry seasons often cause the bats to forage in other areas to find food, in which case bats will be less likely to be observed at Jozani Forest. Many locals view the flying fox as a pest species to their fruit crops and attempt to scare them away. This is another reason why in the future the Pemba Flying Fox might have to rely on protected areas as the low rate of fruit availability is threatening the bats’ survival.