Site description The IBA comprises the entire Cambodian stretch of the Sesan River and associated riverine vegetation, from its confluence with the Sekong River to the international border with Vietnam. The Sesan River is relatively wide, averaging c.150 m wide in the upper reaches and c. 300 m wide lower down. Most sections of the river are dominated by sand and gravel bars, apart from the lowest section, below Phum Khsach Thmei, which is much more rocky. In the upper reaches of the river, bars comprise mostly gravel, often with low shrub growth, while those in the lower reaches are almost entirely sand, with little or no shrub growth. The riverine vegetation is dominated by semi-evergreen and mixed deciduous forest, which grades into deciduous dipterocarp forest away from the river. The riverine vegetation is generally degraded throughout, mainly as a result of shifting cultivation.The IBA supports one of the best remaining examples of the riverine bird community that was once widespread along wide, lowland rivers in Indochina. This community includes River Lapwing Vanellus duvaucelii, Small Pratincole Glareola lactea, Great Thick-knee Esacus recurvirostris and River Tern Sterna aurantia, of which the IBA supports over 1% of the Asian biogeographic population of the former two. In addition, the IBA supports Mekong Wagtail Motacilla samveasnae, a recently described species, which is thought to be endemic to the Mekong River and its major tributaries. Furthermore, the IBA may be one of the last remaining sites in Indochina to support a breeding population of Black-bellied Tern Sterna acuticauda, although this is probably now limited to one or two pairs, and with changes in flow regime following the development of hydropower schemes upstream, on the verge of extinction.
Key Biodiversity Other regionally significant birds recorded: Grey Heron, Purple Heron, Woolly-necked Stork, Cotton Pygmy-goose, Brahminy Kite, Great Thick-knee (13 recorded in May-June 1998 by Timmins and Men Soriyun in prep.), River Tern (47 recorded by Timmins and Men Soriyun in prep. In May-June 1998), Green Imperial Pigeon, Alexandrine Parakeet, Pied Kingfisher (36 recorded by Timmins and Men Soriyun in prep. May-June 1998), Golden crested Myna, Great Slaty Woodpecker, Black Eagle.
Non-bird biodiversity: Timmins and Men Soriyun (in prep.) recorded Long tailed Macaque (Macaca fascicularis) Near- threatened, and Otter sp. Possible Smooth-Coated (Lutra perspicillata) Vulnerable. Baird (1997) reported Irrawaddy Dolphin (Orcaella brevirostris) (data deficient) to have much declined, documenting only a population of 2-5 animals near the confluence with the Sre Pok River. The following red listed fish species presumably occur: Probarbus jullieni, P. labeamajor, Pangasius sanitwongsei, and possibly Pangasianodon gigas. (Rainboth 1996).Long-tailed Macaque (Macaca fascicularis), ang Silvered Langur (Semnopithecus cristatus).Giant Asian Pond Turtle (Heosemys grandis), Siamese Crocodile (Crocodylus siamensis).
ReferencesDavidson, P., Poole, C.M. and J.W. Duckworth 2001. Mekong Wagtail (Motacilla samvaesnae): the great river's only known avian endemic. Bull. Oriental Bird Club 34: 56-59.Davies, J.D. (1994) Wetland surveys in Cambodia to identify sites of international importance. Asian Wetland Bureau, Kuala Lumpur.Duckworth, J.W., Alström, P., Davidson, P., Evans, T.D., Poole, C.P., Tan Setha and Timmins, R.J. 2001. A new species of wagtail from the lower Mekong basin. Bull. British Ornithologists' Club 121(3): 152-182.Goes, F. 1999. Notes on selected bird species in Cambodia. Forktail 15: 25-27.Mundkur, T., Carr, P., Sun Hean and Chhim Somean 1995. Surveys for large waterbirds in Cambodia. March - April 1994. Cambridge, UK: IUCN/SSC.Poole, C. M. Duckworth, J. W. and van Zalinge, N. J. (in prep.) Bird Observations from the Mekong and major tributaries in North-east Cambodia, 1998-2000.Tan Setha (2002) Mekong Wagtail: A species new to science discovered in northeast Cambodia. Cambodia Bird News: 9: 14-17.Thomas, W.W. 1964. A preliminary list of the birds of Cambodia. Unpubl.Timmins, R. J. and Men Soriyun 1998. A wildlife survey of the Tonle San and Tonle Srepok river basins in north-eastern Cambodia. Hanoi and Phnom Penh: Fauna & Flora International and Wildlife Protection Office.van Zalinge, N. J., Poole, C. M., Duckworth, J. W. and Goes, F., (2002). Water bird counts on the Mekong, Sekong, Sesan and Srepok Rivers. Cambodia Bird News 9: 18-29.
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