Oceania & South Pacific Islands

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The South Pacific Islands are scattered over an area of 31,000,000 km², stretching from the Norfolk and Papa Islands in the south, the Marquesas and Pitcairn Islands in the east, Guam and the Marshall Islands in the north, with Papua New Guinea marking the western boundary. The smallest inhabited island is Pitcairn 1, which is just 5 km² and inhabited by less than 100 people, and the largest is Papua New Guinea which is nearly 500, 000 km² in area and home to more than 2 000,000 people (Wodzicki, 1981).

Pacific islands contain the greatest diversity of Pteropus bats and on many they are often the only native terrestrial mammals (Kirsch et al., 1995). Species are often restricted to a single island or group of islands and are therefore the most vulnerable. Problems effecting the habitats are both accidentally and deliberately produced.

Danger from Humans

On the Cook Islands commercial fruit farmers consider fruit bats a pest, although the actual amount of damage to crops is thought to be low (Wahl, 1994). There is no protection for fruit bats and, although a firearms license is required to shoot them, culling is not controlled. Long-term monitoring of the population and the formulation of a management plan for the fruit bat population is recommended, which should include reserved or protected areas or partial or full legislative protection for the species (Wahl, 1994). On New Caledonia fruit bats are managed by the Environment Service and protected by legislation. They do considerable damage to coconut palm plantations and hunting is permitted from April to the end of June. There is a bag limit (10 bats/ hunter/day) and bats may not be marketed at any time (Wahl, 1994). The Tongan fruit bat, Pteropus tonganus, is considered to be moderately common and enjoys full protection on Tonatabu Island where it is considered sacred (Wahl, 1994). On all the other inhabited islands, however, it is hunted frequently. On Guam, the Mariana fruit bat (Pteropus mariannus) is heavily harvested for human consumption, where it is considered a great delicacy. The number of bats remaining are now so low that they cause minimal crop damage. The fruit bats on Western Samoa are protected from killing under the 'Protection of Wild Birds Act' (Animals Amendment Regulation, 1989)(Wahl, 1994). Nevertheless, some hunting still goes on for domestic consumption and tropic storms have had a serious effect on the population in recent times (see the Cyclones & Typhoons page). On American Samoa the fruit bats have been the subject of concern due to heavy population declines due to over hunting and cyclones. In previous decades, when populations where higher, they caused damage to coconut palms, papaya, bananas and breadfruit and were shot by farmers (Pierson et al., 1996). The fruit bats on the Mariana Islands also suffer heavy hunting by the indigenous people who consider them a delicacy. In recent times a hunting ban has been in place, but the population is very low and will take years to recover. A similar situation exists on Palau.

Introduced Plants and Animals

Islands have had a dynamic stability that has in the past made them resistant to invasion by new organisms. Humans discovered and settled the islands comparatively recently and this has had dramatic and sometimes catastrophic effects on their ecosystems. Successive waves of Polynesian, Melanesian and the Micronesian settlers from the Indo-Malayan region brought crop plants and animals like poultry, pigs and the polynesian rat Rattus exulans. Spaniards from the Americas on their early voyages to Guam and the Philippines brought yet more plants and European colonization in the last 2 centuries further increased the number of species of introduced animals and plants and spread them further throughout the islands. The Europeans brought in sheep, goats, cattle, cats and dogs, which sometimes escaped and established wild populations. The ship rat Rattus Norvegicus and the house mouse Mus musculus are now found on most of the islands and do considerable damage to crops and wildlife. The ship rat is believed to be responsible for the decline of sea bird populations and the extinction of at least 4 or 5 endemic land birds on South Pacific islands. Goats and sheep have caused extensive erosion leading to the gradual disappearance of primeval forest habitat.

Feral cats and dogs have had devastating effects on native animal fauna, particularly birds. Cats (Felis catus) arrived on Christmas Island in the Indian Ocean with the first settlers in 1888. Some became wild and established a population of feral domestic cats. A survey of the diet of these feral cats revealed that 80 % of the diet is made up of the island's flying foxes but it is not thought they have a serious effect upon the population (Tidemann et al., 1994). However, two introduced species of arboreal snakes, the brown tree snake Boiga irregularis on Guam and the colubrid snake Aulicus capucinus on Christmas Island are thought to pose a serious threat to bat populations. The brown tree snake was probably first detected on Guam around 1960 and was present throughout the island by 1968 (Lujan, 1992). Wiles (1987) reported that on Guam snake predation was so bad that virtually no juvenile bats survived beyond 1-2 months.

Forest Fires

Bush fires are a very important factor leading to the destruction of native forests and vegetation on many South Pacific islands. Many are started accidentally by careless farmers when they periodically burn the fern land on the hillsides, but sometimes they are deliberately started by mine operators and hunters. These fires often get out of control and can do considerable damage to native flora, causing a gradual receding of the forest margins. Fires are the primary conservation problem on New Caledonia where they sometimes spread over thousands of hectares, and are also frequent on Tahiti and other Polynesian islands (Wodzicki, 1981).

Tourism

Tourism is an increasingly important environmental problem in the South Sea Islands. Well used examples are the damage by careless divers spear fishing and shell taking on coral reefs, and physical damage to coral reefs by the propellors of boats. Tourism has positive economic benefits to the islanders but by-products such as pollution have an undeniable impact on the aesthetic and ecological integrity of the sites. Many Pteropus bats live on atolls, which are highly vulnerable because they have extremely fragile ecosystems, leading some to recommend that no tourism should be allowed on them at all (Wodzicki, 1981).

Mining

Mining is one of the most important factors affecting some of the island ecosystems in the South pacific. Nickel mining on New Caledonia is on such a large scale that it is projected that one third of the island's soil will soon be destroyed. Mined soils are very deficient in nutrients and easily eroded, causing ground and coastal waters to become polluted. The present form of mining on New Caledonia also reduces the forest cover and plant cover. The situation became so worrying that two new organizations were set up by the authorities: The Association pour la Sauvegarde de la Nature NeoCaledonienne, and the Commision de Prevention des Degats Miniers, which comprises representatives from the Departments of Mines, Public Forests and Public works and Science. These official bodies have considerable powers and influence and hopes are high that they will safeguard the ecosystem from the destructive side effects of mining (Wodzicki, 1981).

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

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