Cambodia's northern plains - heartland of Giant Ibis

Cambodia's northern plains are one of the largest remaining intact blocks of a unique landscape that once spread across southern Indochina and Thailand, from Bangkok to Saigon. The plains comprise a complex mosaic of habitats dominated by deciduous dipterocarp forest.

The plains are of exceptional global importance for biodivesity conservation and were formerly the home of the greatest aggregation of large mammals outside of Africa's savannas. Today, many of the large mammals are reduced in mumbers, althrough the landscape is still intact. Key populations of at least 32 mammals, reptiles and birds on the IUCN 2000 Red List occur, including the near-mythical Giant Ibis Thaumatibis gigantea, a bird rarely recorded during the last 100 years, and possibly the legendary Kouprey Bos sauveli, symbol of the Cambodian nation.

Past and present wildlife surveys
Cambodia only recently emerged from three decades of conflict and horrific atrocities. From the late 1960s, the northern plains were a stronghold for anti-government factions, most notably the Khmer Rouge, for whom it was the last stronghold until the final units defected in 1998. The Wildlife Conservation Society (WCS, then the New York Zoological Society) supported a major wildlife survey of the area in the 1950s, with then the Department of Forestry. Only two years ago did it become safe to return, and a joint team from the Ministry of Environment (MoE), the Ministry of Agriculture, Forestry and Fisheries (MAFF), and WCS re-entered the area in November 2000 to begin preliminary wildlife surveys. Early results suggest that, whilst populations of some species (particularly large mammals) were evidently much reduced, an unparalled assemblage of globally threatened and near-threatened species still thrives.

Heartland of the Giant Ibis and other threatened birds
One of the most significant finds was a sizable population of the critically endangered Giant Ibis, centred on Chhep district, Preah Vihear province. Since November 2000, ongoing ground surveys by MAFF/MoE/WCS, supplemented in September 2001 by aerial surveys carried out by the International Crane Foundation (ICF), have recorded a minimum of ca. 50, and potentially up to 90 individuals, with substantial areas of suitable habitat yet to be visited.

Other globally threatened birds found in the northern plains include the critically endangered Slender-billed Gyps tenuirostris and White-rumped G. bengalensis Vultures and the near threatened Red-headed Vulture Sarcogyps calvus. All three have undergone massive declines across Indochina and Thailand, apparently linked to the declines in large mammal mumbers and persecution. Their remnant populations are now centred on Cambodia's northern and north-eastern plains. The endangered White-winged Duck Cairina scutulata occurs in at least two river systems, Greater Adjutant Leptoptilos dubius (Endangered) occurs in small numbers, and Lesser Adjutant Leptoptilos javanicus (Vulnerable) is still widespread and relatively numerous. The vulnerable Sarus Crane Grus antigone breeds in the open flooded grasslands during the wet season (June-October). The vulnerable Green Peafowl Pavo muticus is locally distributed, but in places is not uncommon. The near-threatened Black-necked Stork Ephippiorhynchus asiaticus is widespread in small mumbers, and Woolly-necked Stock Ciconia episcopus, a regionally threatened species, is still relatively common. The vulnerable Greater Spotted Eagle Aquila clanga regularly "over-winters" (some may linger through the rainy season too), and Grey-headed Fish Eagle Icthyophaca ichthyaetus and White-rumped Falcon Polihierax insignis (both near-threatened) occur at low densities. A few Manchurian Reed Warblers Acrocephalus tangorum (vulnerable) winter in sedge and Sesbania scrub stands around pools, and small numbers of Asian Golden Weavers Ploceus hypoxanthus can be found amongst mixed flocks of Baya P. philippinus and Streaked Weavers P. manyar.

One species that hasn't yet been recorded in the northern plains, despite the presence of apparently suitable habitat, is the critically endangered White-shouldered Ibis Pseudibis davisoni. It has undergone a more dramatic decline than the Giant Ibis (it was formerly described as common or very common), and is undoubtedly one of the most pressing conservation concerns in the region. Fortunately, a survey in May 2002, of western Siem Pang district, Stung Treng province, to the east of the northern plains, located the only known significant population of this species in mainland South-East Asia. This survey was conducted by BirdLife International in Indochina, MAFF, MoE and WCS, as part of the Danida funded project Improved Conservation Planning through Institutional Strengthening in Cambodia, Laos and Vietnam.

Regionally threatened birds and deciduous dipterocarp forest specialists
The northern plains also supports an impressive and diverse deciduous dipterocarp bird community. At least 16 woodpecker species occur. Red-breasted Psittacula alexandri and Blossom-headed P. roseata Parakeets are widespread and common, and Alexanderine Parakeet P. eupatria (now extremely rare across much of South-East Asia) remains locally common. Nocturnal birds include Oriental Scops Owl Otus sunia, Indian Caprimulgus asiaticus and Savana C. affinis Nightjars, Spotted Owlet Athene brama, Brown Strix leptogrammica and Spotted S. seloputo Wood Owls, and, in copses of semi-everygreen forest, Javan Frogmouth Batrachostomus javensis. Yellow-footed Green Pigeon Treron phoenicoptera, another deciduous dipterocarp forest specialist, is locally common, as is Green Imperial Pigeon Ducula aenea. Eurasian Thick-knee Burhinus oedicnemus occurs sparsely in agricultural fringe habitats and raptors are well represented (16 species have been identified to date).

Mammals
The plains are crucial to large mammal conservation in the region. Many formerly widespread species are now restricted to a few localities, of which the northern and north-eastern plains are the largest, with the greatest potential for conservation. Examples include Eld's Deer Cervus eldii (represented here by the Indochinese subspecies siamensis, previously considered to be close to extinction), Banteng Bos javanicus, Tiger Panthera tigris, Asian Elephant Elephas maximus and Fishing Cat Prionailurus viverrina. Recent surveys have discovered Wroughton's Free-tailed Bat Otomops wroughtoni, a critically endangered species previously known only from a single cave in western India. Pileated Gibbons Hylobates pileatus still sing in the tracts of evergreen forest, Asiatic Jackal Canis aureus is common, Dhole Cuon alpinus is widespread but less common, whilst Jungle Cat Felis chaus also occurs. Other globally threatened resident mammals include Pygmy Loris Nycticebus pygmaeus, Pig-tailed Macaque Macaca nemestrina, Gaur Bos gaurus, Southern Serow Naemorhedus sumatraensis and East Asian Porcupine Hystrix brachyura. Like the large waterbirds, many of these species concentrate at a few key localities during infertile or dry periods, and disperse widely across the foodplains when water enriches the soil.

The northern plains are possibly the only area in the world where Kouprey still exist. This charismatic wild cattle species has been extirpated from its former range spanning southern Laos, eastern Thailand and southern Vietnam. The only recent reports come from the forests of the northern plains, and any surviving populations would have important ramifications for Cambodia's conservation efforts, for their symbolic value to the nation and for their national and international conservation profile.

Threats and root causes
The area has avoided large-scale destruction due to its insecurity and consequent inaccessibility. Few people live there, but already development has begun and there are localised problems with uncleared landmines. Provincial development plans outline road construction, the opening of international border posts, and the resettlement in outlying rural areas of returning refugees and former soldiers. Although some of the semi-everygreen forest areas are being heavily exploited, deciduous dipterocarp timber is of little value to commercial forestry. However, there are plans for future mining and large-scale agricultural development.

The single greatest threat to most of the large mammals, and other animals, is hunting, both professionally to supply the international demand for wildlife trophies and traditional medicine, and opportunistically to serve internal or local markets. Subsistence hunting appears mainly to focus on a few commoner species, a factor that should assist efforts to reduce the loss of key species through community involvement.

Future conservation prospects
The landscape is clearly of global biodiversity importance, yet it is still relatively poorly understood. WCS has recently initiated an extensive effort to gather essential data on both human and wildlife use of the landscape, and to locate, map and analyse the threats to critical resource sites for the key wildlife species. Crucially, the project also aims to ensure that the landscape and its critical areas are represented in provincial and national land use planning processes, and that sufficient resources are committed to the area to promote long-term sustainability. Through the appropriate management of localised key sites, a far greater area with differing human-use patterns can be managed for the effective conservation of this unique landscape and its wildlife.

Four areas within the northern plains have recently been identified as Important Bird Areas (IBAs): Chhep, O Skach, the Upper Stung Sen river and the Upper Chikreng river. These are among the 41 IBAs in Cambodia recently identified as part of a joint project between BirdLife International in Indochina, WCS, MAFF and MoE. These IBAs are a foundation for future conservation efforts in the northern plains, in the form of local stakeholder support groups, a pilot of which has recently been successfully established at the Upper Stung Sen River IBA.

For more information, please contact wcs@bigpond.com.kh
Peter Davidson, Colin Poole and Joe Walston
Wildlife Conservation Society Cambodia Programme
P.O Box 1620, Phnom Penh, Cambodia
Tel/Fax: +855-23-217205