The Great Lake of Tonle Sap is the largest natural freshwater body in South-east Asia. The river from which it takes its name, the Tonle Sap, joins with the Mekong. Because of the low-lying terrain and the strongly seasonal climate, the river shows a remarkable seasonal reversal of flow: in the dry season water flows from the Tonle Sap into the Mekong, but in the wet season, when the Mekong rises rapidly, water flows from the Mekong back into the lake. Sometimes called the ‘heart of South-east Asia’ this seasonal flow reversal is vitally important to the area’s ecology, including the highly productive fishery (one of the most productive in the world). The Great Lake was designated as a Biosphere Reserve by UNESCO in 1997 and by the Royal Government of Cambodia (RGC) in 2001. It includes three core areas, of which Prek Toal is one. Prek Toal is recognised as a site of high global conservation significance primarily due to the presence of breeding colonies of some of the world’s most threatened water-bird species, including seven Globally Threatened or Near Threatened species. The most threatened of these colonial large-water birds at this site, globally, is the Endangered Greater Adjutant.
The Wildlife Conservation Society has been working in collaboration with the Royal Government of Cambodia’s Ministry of Environment at Prek Toal since 2001. Before 2001 the primary threat to large water-birds at Prek Toal was the collection of eggs and chicks for sale by local people, with an estimated 26,000 eggs and 3,000 chicks collected from these water-birds during the 1996/1997 breeding season. Unlike with much trade-driven hunting in South-east Asia, the eggs and chicks were for local sale, and the collectors were the poorest people living locally. This proved the key to success. Following two years of incomplete monitoring, in 2003 a comprehensive monitoring and protection programme was set up by WCS and MoE whereby MoE rangers would count birds, chicks and nests at the colonies from a number of vantage platforms located in the top of trees where staff were permanently based during the breeding season (each person on rotation). From these platforms, they would also protect the colonies from poachers. Former egg collectors, with their limited options for legal work, were, mostly, eager to be recruited as rangers, and they provided local knowledge on the bird nesting locations and behaviours. This monitoring has continued every year since 2003, and has been supplemented by additional patrols around Prek Toal. The ranger surveillance from platforms has proven a very effective deterrent, and chick and egg collection has almost ceased since then. The exception to this was during a large storm in 2009 when the rangers were absent from the platforms for two nights, which was followed by incidences of water-bird eggs for sale in local villages.
The populations of all seven monitored water bird species have increased, in some cases dramatically. This includes the increase in number of breeding pairs of the Endangered Greater Adjutant from an estimated 56 pairs in 2004 to 126 pairs in 2010. With an estimated 800-1000 individuals left in the wild, this represents a significant success for this population, especially considering that Prek Toal is one of only three breeding populations in the world: of the others, the largest in Assam, India, has shown recent breeding failures, while the third, in Bihar, India, had only 32 pairs (in 2008). The only other known breeding area in Cambodia is in Preah Vihear province, with 5–10 pairs; these are probably part of the same breeding population as Tonle Sap. In addition to the seven water bird species that are monitored at the colonies, there has also been an increase in the number of nests of the Globally Near Threatened Grey-headed Fish Eagle. In 2010, Prek Toal staff agreed to collaborate with the EU-funded ACCB (Angkor Centre for Conservation of Biodiversity) over injured and rescued birds in need of rehabilitation. This has continued to date. In addition to the water birds, Prek Toal is also home to populations of the Critically Endangered Siamese Crocodile, and the Endangered Masked Finfoot and Hairy-nosed Otter. Rangers record other species sighted at the platforms, and in the last two years, this has included sightings of Masked Finfoot, Siamese Crocodile, Hairy-nosed Otter, Smooth-coated Otter and Long-tailed Macaque, among others.
WCS also collaborates with the Royal Government of Cambodia’s Fisheries Administration, and in 2008–2009 conducted a research project to assess the conservation, fish catch, and socio-economic benefits of the current management system of the Prek Toal core area and the over-lapping commercial fishing lot. WCS is also collaborating with the Fisheries Administration over the release and tracking of some wild-caught Critically Endangered Siamese Crocodiles. The project at Prek Toal has benefited enormously from some donors. In particular, Danida/DFID, GEF (through UNDP and TSCP), and CEPF, although the premature end of the Tonle Sap Conservation Project has meant an end to some funding earlier than expected. Tourism at Prek Toal is fairly well established (benefiting from its proximity to the famous temple of Angkor Wat, and easy day-trip access), and there are a lot of visitors from the EU and USA. Since 2010, WCS has worked with the MoE to improve transparency of the use of the tourist entrance fee. It has been agreed that this fee will go towards local communities, and to help support conservation activities, as well as the obligatory proportion which goes to the government. This process is still in its early stages, but it is intended to give some money accrued to conservation and communities during 2011. However, the amount of money currently gained through tourism is small (less than 10% of the running costs of the water-bird conservation project, including the money ear-marked for communities).