Visit Organic Bouquet, the world’s first online organic florist, from our website and Lubee will receive a 10% donation for each order of organic flowers purchased.
About Fruit & Nectar Bats - Why Conserve Fruit & Nectar Bats? | Fruit & Nectar Bat Biology | Global Conservation & Distribution Status | Global Conservation Threats | Regional Conservation Issues | Literature on Fruit & Nectar Bats
Declines in fruit bat populations in recent years due to habitat destruction, hunting, and natural disasters have led to concern for their long term survival.
Deforestation is widespread throughout the tropics and poses a major threat to Pteropus bats because forests provide them with food and roosting sites. The dwindling supplies of timber in developed countries and the massive demand from Japan for wood-chip, plywood and logs are major components in the problem of tropical deforestation. Furthermore, the removal of large trees by heavy equipment combined with heavy rainfall damages the top soil and compacts it preventing new canopy trees from germinating. The soil is then taken over by mats of quick growing creepers (such as Merione, Mikania and Passiflora in the South Pacific), which further inhibits regeneration, and so a whole eco-system is destroyed (Wodzicki, 1981).
The Pacific Region contains 25,000 mostly small islands and the two major causes of the decline in fruit bat populations on these islands are habitat destruction and hunting. Deforestation by man has been going on for centuries and most of the largest and best bat habitats were lost a long time ago. Where humans and fruit bats meet there is a conflict of interests - both exploit the same kind of habitats. The kind of forest preferred by fruit bats is usually primary forest, but that is also where the largest and most valuable trees are found and so it is the part of the forest most under pressure from loggers. Humans and fruit bats both have their biggest populations on the larger pacific islands. Human population increases in the last 20 years have lead to a massive increase in the rate of deforestation. In the mid 1980s it was estimated by Marten (1985) that if it had continued at its present rate the inhabited pacific islands would have been completely deforested in less than 20 years. Heavy logging is presently taking place on many islands in the South Pacific such as Papua New Guinea, Fiji, Western Samoa (where 500-600 ha are logged annually) and the Solomon Islands. If the present trend continues it will mean that the only surviving Pteropus species will be those occurring on small uninhabited islands.
Most Pteropus bats live on islands that are subjected to frequent tropical storms. In the past these forests were large enough to resist the strong winds and rains but deforestation has meant that the smaller patches of trees left standing are more easily blown down by the winds and the reduced root networks are undermined by the heavy rain, which allows the soil to be washed away.
Those Pteropus species living in the fragile mangroves of Malaysia and Indonesia such as Pteropus vampyrus also suffer from rapid loss of habitat as the trees are cleared to make way for shrimp farms.
Shrimp aqua-culture has been practised for centuries but in the last 20 years it has boomed in response to the huge demand for shrimp on the world market, and is now a major industry in the tropical regions of Asia and, to a lesser extent, South and Central America. Thailand, Indonesia, China and other Asian countries now have in the region of 1.2 million hectares of shrimp farms and Thailand alone produces 165,000 tonnes of shrimp a year. Most of the shrimps produced end up for sale in markets in Europe, USA and Japan (Boyd & Clay, 1998).
Displacement of the mangrove forests to make way for shrimp ponds has been a major environmental concern. In parts of the Old World tropics, and particularly South East Asia, their destruction has reached epidemic proportions. Half of the world's mangrove swamps have now been destroyed. In past centuries much of this was done by people cutting down the trees for wood but more recently shrimp farming has become the major cause in some areas. These fragile ecosystems provide important habitats for many endangered animals including many species of Pteropus bats like Pteropus molossinus on Pohnpei and the Australian species. Mangroves prevent eutrophication of coastal waters by absorbing nutrient run-off and provide safe environments for the development of young marine animals. Furthermore, these areas are simply not suitable for sustainable shrimp aqua-culture, economically or environmentally. The soils often lack the properties required for long-term farming and they are vulnerable to coastal storms. What follows is constant relocation of ponds due to bad planning and insufficient prior knowledge of the suitability of sites, which is both environmentally destructive and expensive. Fortunately, most large-scale shrimp producers have started to realize this and now set up their farms further inland with canals and pipes to transport water through the mangroves from the sea. The Indonesian government requires some larger operations to help smaller and fledgling ventures manage their ponds.
A growing awareness of shrimp farming's bad image has prompted a response from a number of leading international bodies. The Global Aquaculture Alliance (GAA) has put forward recommendations based on guidelines for responsible aqua-culture presented by the Food and Agriculture Organization (FAO) of the United Nations in Article 9 - Aquaculture Development of the Code of Conduct for Responsible Fisheries to promote 'environmentally and socially responsible shrimp farming'. The guidelines give considered advice on areas like choosing sites (not in mangroves), reforestation and waste disposal in the interests of local communities, long term efficiency and profitability and environmental sustainability.
See more on the GAA website
Shrimp farming has caused massive destruction to the mangroves along the Mekong delta in Vietnam, where half the mangrove forest has been cut down for wood or cleared for shrimp farms. In response to this a project run by the Australian Institute of Marine Science Collaborators Institute for Aquaculture (AIMSCIA) has been commissioned by the Australian Centre for International Agricultural Research (ACIAR), which commissions a lot of conservation work in South East Asia and the Pacific region. The aim is to enhance understanding of shrimp aqua-culture 'through study of pond ecology, nutrient dynamics, water quality and their effects on yields of shrimp' in order to develop more efficient (and presumably less destructive) management methods for mangrove resources.
Hunting bats for food has long been practised in most of the areas where fruit bats and man coexist. They can be found for sale, alive or dead, on markets in Indonesia and Malaysia where they are eaten by the Chinese and Manadonese communities (Fujita & Tuttle, 1991). Some communities believe eating fruit bats can cure such diverse ailments as asthma, kidney complaints and even tiredness (Fujita & Tuttle, 1991), but in most places they are simply seen as good eating. This is particularly so on Pacific islands. The market for fruit bats (Pteropus spp. & Acerodon spp.) for sale on islands like the Commonwealth of North Mariana Islands (CNMI), Guam and Saipan, where they are eaten as a luxury food item, has boomed over the last 3 decades, placing great pressure on the populations of bats on those and neighbouring Pacific islands. Bat populations have been hit hardest on the islands of Palau, Chuuk and Pohnpei, which have become the main exporters of fruit bats in the region (Pierson & Rainey, 1992; Wiles, 1992).
Most Pteropus batslive on small islands, many of which are frequently hit by tropical storms such as typhoons (in the Pacific) and cyclones (in the Indian Ocean). The devastating effects of these storms on island biotas are particularly pertinent to frugivores and nectivores like fruit bats. This has been demonstrated by the substantial population declines of Pteropus rodricensis on Rodrigues Island and P. niger in Mauritius in the Indian Ocean; P. mariannus on Guam and P. samoensis and P. tonganus on Samoa in the Pacific in recent years following storms (Pierson et al., 1996; Craig et al., 1994).
Forest remnants on islands are particularly vulnerable to the tropical storms and cyclones that ravage the pacific. In the past these forests were large enough to resist the strong winds and rains, but deforestation in recent decades has meant that the smaller patches of trees left standing are more easily blown down by the wind, and reduced root networks fail to prevent heavy rain washing away the topsoil. The effects of deforestation on soil systems was most tragically demonstrated when Hurricane Mitch hit Central America in October of 1998. Rivers of mud washed away crops, towns and villages because the removal of the forest had resulted in a much weakened soil structure. When a tropical storm hits a small island it causes habitat destruction by flattening trees, destroying food sources and roosts. In the past the bats were able to relocate to undamaged forest on the same island or others nearby. In recent years, however, reduced habitat leading to fragmentation and reduction of bat populations has meant that bats suffer much more from the effects of tropical storms. Natural disasters now destroy a much greater proportion of the remaining forest fragments, leaving the bats with little or no alternative refuge or forcing them into poorer, sub-optimal habitats (Pierson et al., 1996).
Cyclones are common in the Indian Ocean. The cyclone gets its energy from the sun heating the Earth unevenly in places creating masses of warm air and cool air. Cold air masses or 'fronts' generally move faster than warm air fronts so when the two meet they start to move round each other resulting in winds. Cyclones are associated with heavy rains. which are formed when the warmer air rises and begins to cool at high altitude. Unlike storms, which are formed by a similar process, cyclones always spin in an anti-clockwise direction in the Northern Hemisphere and clockwise in the Southern Hemisphere. A second cyclone can sometimes split off from the first, and a cyclone may last one or two days before it begins to lose form and strength and eventually fall apart. A serious cyclone has winds in excess of 64 knots but most cyclones are benign and do little damage - in fact they account for most of the weather at mid-latitudes.
Information on this page was compiled and authored by Oliver Thatcher and is currently being updated.
Back to Top
