Afrotropics & Western Indian Ocean Islands

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The Comoro Archipelago lies in in the Western Indian Ocean 300 km off the coast of Mozambique. These islands are home to the Critically Endangered endemic fruit bat Pteropus livingstonii, the Low Risk P. seychellensis comorensis (Baillie & Groombridge, 1996), and thenocturnal Rousettus obliviosus. Pteropids are known to occur on the three islands that comprise the Federal Islamic Republic of the Comoros (RFIC). The fourth island, Mayotte, has lost most of its forest habitat and fruit bats are no longer thought likely to exist there (Thorpe et al., 1988). In the two large blocks of forest remaining on the largest island, Grande Comore, no Pteropus livingstonii have been sighted since before Cheke and Dahl made their survey of the islands in 1975 and 1977 (Cheke & Dahl, 1981). However, the the 1988 University of East Anglia (UEA) Comores expedition team who surveyed the species in 1988 did report sightings of P. seychellensis in the disturbed La Grille forest on Grande Comore (Thorpe et al., 1988). The forests of the island of Anjouan are located in the central highland region of the island but are under planted with banana, with only a small portion of primary forest remaining. 75 % was under planted with banana between 1974 and 1983, increasing the island's vulnerability to cyclones (Anon., undated: IUCN, Species Action Plan for Livingstone's fruit bat). Despite this, a population of P. livingstonii survive there. Moheli is the only other island where both P. seychellensis and P. livingstonii still survive although it too has suffered severe deforestation. 53 % of the primary forest was lost between 1973 and 1983 and two severe cyclones hit the islands in 1980 and 1983, possibly reducing the bat population further (Thorpe et al., 1988).

Deforestation is undoubtedly the greatest threat to the future of P. livingstonii in the wild and seems set to quickly eradicate native habitat on Anjouan and Moheli in the near future. Without prompt intervention the long-term survival of these bats in the wild seams highly in doubt. 70 % of the primeval forest has been destroyed since 1972, and now only 21.6 km2 remain on and 15.5 km2 remain on Moheli (Anon., undated: IUCN, Species Action Plan for Livingstone's fruit bat). The removal of trees has had disastrous consequences for the water retention ability of the soil, and as a result only 11 of the 45 rivers flow year round on Anjouan (Anon., undated: IUCN, Species Action Plan for Livingstone's fruit bat). The RFIC is the poorest African state and has enormous economic problems and population growth (Thorpe et al., 1988). Forest clearance provides land for subsistence agriculture and provides wood for domestic consumption and export (Clarket al., 1997). This loss of habitat deprives the bats of roosting sites and food, and it is estimated that if the current trend continues P. livingstonii will be extinct in the wild in less than 10 years (Mickleburgh et al., 1992). It should be added that the Comorien fruit bat, P. seychellensis comorensis, actually adapts rather well to disturbed forest and the population is not considered to be in great danger (Baillie & Groombridge, 1996; Herron, 1993).

Conservation Action

In 1988 the chiropteran specialist group of the Species Survival Commission of the International Union for the Conservation of Nature and Natural Resources (IUCN) initiated an action plan to protect Pteropus species. The IUCN assigned Pteropus livingstonii priority grade 1 status (now classified as Critically Endangered in the latest IUCN red list [Baillie & Groombridge, 1996]). Several initiatives were instigated to address the environmental and conservation problems on the Comores involving long-term environmental management on the islands of Moheli and Anjouan (Mickleburgh et al., 1992). Since 1993 the RFIC has entered into a number of international environmental treaties including the Convention for the Protection of the World Cultural and Natural Heritage; the Convention for the Protection, Management and Improvement of Marine Environments and Coastal Zones; and the Convention on Biological Diversity. Action Comores has been working closely with the RFIC government to advise environmental policy making to implement their obligations under the treaties. A major problem is lack of funding for enforcement of any such legislation. On Moheli, for example, there is only one enforcement officer and no jail. Poaching of valuable trees and illegal cultivation in protected areas are lucrative and at the moment there is little to deter law breakers. Those who are caught are often repeat offenders, making the question of suitable deterrents a primary area for improvement.

Pemba Island

Pemba is a small island, only 68 km long and 23 km wide, lying 40 km off the coast of Tanzania in the western Indian Ocean (Entwistle & Corp, 1997a). Although Pemba is home to four species of fruit bats, its only endemic mammal species and the only representative of the genus Pteropus is the Pemba Island fruit bat, Pteropus voeltzkowi (Entwistle & Corp, 1997a; Mickleburgh et al., 1992).P. voeltzkowi is classified as Critically Endangered by theIUCN, with a high risk of extinction in the wild in the immediate future (IUCN: Baillie & Groombridge, 1996), and a small population with a range restricted to just 1014 km2 (Entwistle & Corp, 1997a).

Pteropus voeltzkowi

Description: The largest fruit bat on the island. The fur is chestnut red.
Diet: The diet is wide and includes 28 species of plants. Parts eaten are the fruits (which accounted for 87 % of faecal samples), flowers, pollen and leaves (Entwistle & Corp, 1997b). Leaves are thought to provide protein and minerals (Kunz & Diaz, 1995). Mango (Mangifera indica), a cultivated species, is the most important fruit in the diet, but breadfruit (Artocarpus altilis) and figs (Ficus spp.) are also important. It may be one of the only species on the island to disperse larger seeds, indicating its importance in the eco-system (Entwistle & Corp, 1997b).
Reproduction: Mating probably occurs between January and April, with births taking place between June and August. Males are larger than females and darker in colour.
Population: Population estimates have been hampered by the fact that local people are unaware that there is more than one fruit bat species on Pemba. The most recent estimates from the survey of Entwistle and Corp, 1997a, place the population at between 4608 and 5458 adult individuals, with 94 % of these residing in just 10 camps (Entwistle & Corp, 1997a).
Roosts: Pteropus voeltzkowi roosts in large camps of up to 855 individuals, or solitarily in sites removed from human settlements. A preference for large, mature trees of the families Mangifera, Erythrophleum and Afzelia and strong fidelity for traditional sites has been noted (Entwistle & Corp, 1997a). These sites are most often found in primary and secondary forest, with traditional graveyards (which are protected from disturbance by local taboo) providing important habitat as well. A single roost has been reported in mangrove forest. Entwistle and Corp (1997a) observed a total of 19 occupied roosts, mainly located in the west of the main island, and some on the smaller islands.

Threats

Habitat loss, hunting and agricultural/urban disturbance are the most serious and common threats to Pteropus voeltzkowi. An increasing human population is rapidly decreasing the available habitat, as the native forest is cleared for agriculture and trees are felled for timber and firewood. Logging has caused the disappearance of several roosts in recent years (Entwistle & Corp, 1997a). Hunting is not thought to be performed on a commercial basis, but most roosts suffer from some. A high fidelity for traditional sites increases the vulnerability of the bats by making them easier to find. The most popular methods of hunting are traditional and not thought to cause serious damage to populations. Shotguns, however, are used at most of the known roosts and cause quite considerable destruction (Entwistle & Corp, 1997a).

Conservation Action

The problems of habitat destruction and hunting must be addressed but these are delicate issues and consideration of the needs of the local people is essential (Pakenham & Seehausen, 1992). Bats are an important protein supplement in the diet of the local people and so alternatives must be identified. The poor quality of the soil of the region necessitates the frequent abandonment of plantations and the clearing of forest to provide new ground, and timber is required for building houses for the growing population. Education of the people and advice and support from the conservation community is needed for the development of sustainable alternatives.

A captive breeding programme is currently underway at the Phoenix Zoo in Arizona, USA. It was established in 1994 in response to surveys of the population and the recommendation for a captive breeding programme in the IUCN Action Plan for the Conservation of Old World Fruit Bats (Mickleburgh et al., 1992). There are no laws that restrict hunting of fruit bats on most of Pemba. However, hunting is restricted in two fragments of forest, and a camp of P. voeltzkowi has been sighted in one of these, Ngezi forest, which covers an estimated 12-15 km2 (Pakenham, 1984).

Information on this page was compiled and authored by Oliver Thatcher and is currently being updated.