Late quaternary turnover of mammals in Borneo: the zooarchaeological record

The Quaternary has been a period of repeated, oscillating patterns of climate change. Global fluctuations in sea level affected the island status of Borneo, which was probably joined to continental Asia for more than half of the last 250,000 years. Alternating connection and isolation, coupled with the ecological barrier of a savanna corridor running from the Malay Peninsula to Java during periods of marine recession, are reflected in the present mammal fauna of Borneo. 38% of mammal species (excluding bats) are endemic, and some distinctive species or subspecies are confined to the north of the island. No known sites in Borneo match the Early and Middle Pleistocene regional sources in eastern Java. However, caves at Niah, Sireh and Jambusan, Sarawak, and Madai, Sabah, provide a zooarchaeological record covering the past 50,000 years. The Late Pleistocene mammals of Borneo included ten species also present among a Javan Middle Pleistocene savanna-adapted assemblage. Of these, four are categorised as ‘megafuana’: a giant pangolin, Javan rhinoceros, Malay tapir and tiger; the Sumatran rhinoceros can be added. In addition, there are less secure Pleistocene records of Asian elephant from Sarawak and Brunei. Holocene canid remains from Madai could either be the dhole or an early domestic dog. Palynological data combined with the mammal fauna confirm that around 45,000 years ago the vicinity of Niah was vegetated by closed forest. The continuous presence of a suite of arboreal specialists, including large primates, indicates that forest cover persisted through the terminal Pleistocene. Among local extinctions, the giant pangolin apparently disappeared early in this period, but tiger, Javan rhinoceros and tapir probably survived into the last millennium. Human predation of juveniles may account for the loss of the large ungulates, but the disappearance of tiger needs another explanation. Despite hunting pressure throughout the terminal Pleistocene and Holocene, a population of orangutan survived at Niah until perhaps the last millennium. Size diminution observed among large, medium and small mammal species is interpreted as the selective impact of environmental change. Once more is known about their ecology, changes in the bat fauna of Niah cave may provide indicators of environmental impacts affecting the wider mammal community during the later Holocene. In conclusion, it is recommended that the three nations, Brunei Darussalam, Malaysia and Indonesia, should support the WWF sponsored ‘Heart of Borneo’ as the most hopeful project to provide sustainable management of the rare and threatened forest-adapted wild mammals of the island.