Monitoring biodiversity and the ecological condition of a habitat provides crucial feedback on the success of conservation actions and habitat management activities. We have monitored orangutan population density since 1999 – initially highlighting the importance of the Sabangau Forest for orangutan conservation, then showing how uncontrolled logging was causing a dramatic decline in numbers. Results since 2004 demonstrated that CIMTROP’s success in halting illegal logging in the LAHG was matched by a halt in the decline in orangutan numbers. The population has stabilised and is now increasing again. During 2007-08 we are establishing seven further monitoring sites in the LAHG, at which we will measure annually orangutan density; gibbon density; tree biomass, growth and death rates and other aspects of forest biodiversity. We have completed pilot surveys of bird diversity and abundance, butterfly diversity and abundance, diurnal and nocturnal primate density and ground beetle diversity, and we will use the most suitable of these as indicators to monitor changes in habitat condition.

OuTrop have been surveying the Sebangau catchment for the presence of orang-utans since 1995. Since that time, many locations have been surveyed using a standardized transect method developed in Sumatra. The presence of orangutan nests (sleeping platforms) has been confirmed at every single location, suggesting a large and continuous population. By combining satellite imagery data of forest type across the catchment with known densities on the ground, it has been possible to estimate that the total Sebangau population is around 6,900 individuals. This represents the largest single population of the Bornean orang-utan in the world.