Effects of human landuse on faunal abundance in some Thai forest reserves

Habitat fragmentation involves the reduction and isolation of natural areas, and is a serious threat to wildlife. An important objective for wildlife managers is to identify species that are sensitive to fragmentation and the specific ecological consequences of fragmentation to which each species is sensitive. Large mammals are targeted by poachers and are among the first wildlife to disappear from forests following fragmentation. In this study, the distributions of large mammals and the composition of mammal assemblages were compared across forest conditions ranging from small fragments to extensive transboundary areas. Interview surveys of rangers and local people were used to determine where large mammals were concentrated inside reserves. Systematic camera-trapping and sign surveys were done in these areas for carnivores, ungulates and other large mammals. Encounter rates of signs and capture rates from camera-traps showed that large mammal composition and abundance varied between sites. Transboundary rainforests on the Thai-Malaysia border had the most abundant populations of focal species (elephants, wild cattle and tigers), the highest traffic of large mammals, and were species rich for ungulates. Forests that are narrow and internally fragmented by roads have the poorest large mammal faunas and lowest traffic mammal traffic. Geographic Information System (GIS) databases were used to map distributions of large mammals within two study areas, and assess how different species are affected by human disturbances in the landscape. At rainforest sites, carnivore abundance was influenced by factors such as proximity to roads, drainages, and levels of prey. Large ungulates (sambar and gaur) distributions were highly predictable inside another large reserve, suggesting close affinities with habitats, including saltlicks and grasslands managed by annual burning. Bear and elephant distributions were less predictable and possibly more influenced by the patterns of hunting inside the reserve. In general, poaching inside Thai reserves and the internal fragmentation of reserves by roads that facilitates access to poachers, are arguably the most serious threats to large mammals, especially those with commercial value either alive or dead. The research was conducted in collaboration with Royal Forest Department staff, students and local people. Field methods developed during the project were taught to these individuals through on-the-job training and special training courses.