(I) Physical CharacteristicsThe proposed Kinabatangan Wildlife Sanctuary is essentially an important floodplain in Sabah and also the largest. The area comprises tracts of land that link the mangrove areas near the coast with the existing protected areas further inland, creating a corridor of floodplain habitat to maintain the ranging patterns of native wildlife (Prudente and Balamurugan, 1999). Several natural habitat types are found here such as limestone outcrops, oxbow lakes, riverine forest vegetation, dry lowland dipterocarp forest, seasonal swamps and tidal mangroves (WWFM, 1998, n.d.).Sungai Kinabatangan, Sabah's largest and longest river (560 km), runs through the floodplains, which is subjected to seasonal flooding. The river has a catchment area of about 1,680,000 ha, covering almost 23% of the total land area in Sabah. The southern branch of the river originates in the Kuamut Highlands while the northern branch originates from Banjaran Trus Madi and Labuk Highlands. The river flows eastwards before discharging into the Sulu Sea. The main tributaries of the Kinabatangan are Kuamut, Milian, Sapasidom, Menanggul, Tenegang Besar, Koyah, Maliau, Pinangoh and Lokan (Prudente and Balamurugan, 1999). (II) Climatic ConditionsMean annual rainfall is approximately 2,600 mm, well distributed with slightly more in December and January. Lowest rainfall occurs in March-April. Mean diurnal temperature average between 32-22oC (DWNP, 1987).
The Kinabatangan wetlands is an important site for several globally threatened waterbirds especially Storm's Stork Ciconia stormi, where the last viable population in the country remains. One hundred and eighty-nine bird species have been recorded and some breeding (Sharma, 1992). The Near Threatened Oriental Darter Anhinga melanogaster is found to be common and breeding in the area (Sharma, 1992; Smythies, 1999; Sheldon et al., 2001). Others include the wetland raptors Grey-headed Ichthyophaga ichthyaetus and Lesser Fish-eagle I. humilis (Sharma, 1992). Locally, the Gomantong Caves is one of Sabah's two most important sites for birds' nest trade (WWFM, n.d.).
Non-bird biodiversity: About 50 species of mammals are recorded including a small population of the Asian Elephant Elephas maximus and possibly the Sumatran Rhinoceros Dicerorhinus sumatrensis (WWF, 2002a; Payne and Francis, 1985). The Kinabatangan contains the largest Malaysian population of Proboscis Monkey Nasalis larvatus (Buckley, 2002; Bennett and Gombek, 1993; Prudente and Balamurugan, 1999). Twenty-seven species of reptiles and amphibians were recorded (Sharma, 1992; Whittaker, 1984). Freshwater fish diversity and productivity is very high. More than 100 species have been recorded so far. The Irrawaddy Dolphin Orcaella brevirostris have been reported 20 km up Sungai Kinabatangan (Dolar et al., 1997 in Smith and Jefferson, 2002). Recently, the Borneo River Shark Glyphis sp. known from a few immature specimens, not yet named and thought to be extinct, was rediscovered in the lower Sungai Kinabatangan. This species was listed as Critically Endangered in the 1996 IUCN Red List of Threatened Animals (Prudente and Balamurugan, 1999). Plants of special interest in this region include Koompassia excelsa, Terminalia copelandi, Ficus racemosa and Mitragyna speciosa (Boonratana, 2000; Reza Azmi, 1998; Sharma, 1992).(I)Globally threatened mammals (IUCN, 2002): CRITICAL: Sumatran Rhinoceros Dicerorhinus sumatrensis; ENDANGERED: Asian Elephant Elephas maximus, Proboscis Monkey Nasalis larvatus, Tembadau Bos javanicus, Orang-Utan Pongo pygmaeus; VULNERABLE: Pig-tailed Macaque Macaca nemestrina, Common Porcupine Hystrix brachyura, Smooth Otter Lutrogale perspicillata, Clouded Leopard Neofelis nebulosa, Flat-headed Cat Prionailurus planiceps, Bare-backed Rousette Rousettus spinalatus; NEAR THREATENED: Long-tailed Macaque M. fascicularis, Bornean Gibbon Hylobates muelleri, Pangolin Manis javanica, Oriental Small-clawed Otter Amblonyx cinereus, Gilded Tube-nosed Bat Murina rozendaali, Philippine Horseshoe Bat Rhinolophus philippinensis; DATA DEFICIENT: Hairy-nosed Otter Lutra sumatrana, Irrawaddy Dolphin Orcaella brevirostris, Hose's Langur Presbytis hosei, Malayan Sun Bear Helarctos malayanus(II) Globally threatened reptiles (IUCN, 2002): (III) Globally threatened plants (IUCN, 2002):
BirdLife International (2019) Important Bird Areas factsheet: Kinabatangan floodplain. Downloaded from http://www.birdlife.org on 27/06/2019.