Population Density and Social Behavior of Lowland Anoa (Bubalus depressicornis) and Sympatric Forest Ungulates in Tanjung Peropa and Tanjung Amolengo Wildlife Reserves, Southeast Sulawesi, Indonesia

Lowland anoas occur widely within the forests but at low densities, inhabiting many habitat types – including beach, riverine, bamboo, lowland forests, and forests at higher altitudes of up to 900 masl in Tanjung Peropa and Tanjung Amolengo Wildlife Reserves in Indonesia. This study aimed to estimate population density, distribution pattern, and to reveal the social organization of the endemic forest ungulate. Line transect was used to estimate population density; direct encounter was used to describe the social behavior of the lowland anoa. Population densities were estimated to be 0.9 anoas/km2 and 1.1 anoas/km2 in Tanjung Peropa and Tanjung Amolengo Wildlife Reserves, respectively. Based on this density, the population sizes of lowland anoa were estimated to be 350 individuals in Tanjung Peropa and only seven individuals in Tanjung Amolengo. Lowland anoas were mostly found singly (84%), some in pairs (16%), and rarely were three animals found in a group. Population densities of Sulawesi warty pig were 5.6 pigs/km2 and 14.4 pigs/km2 in Tanjung Peropa and Tanjung Amolengo respectively. Index of dispersion of lowland anoa were 0.11 and 0.19 (s2/ x̅ ˂1) in Tanjung Peropa and Tanjung Amolengo respectively, indicating that the animals distribute regularly in their natural habitats. Index of dispersion of the Sulawesi warty pig and rusa deer were 1.78 and 1.51 (s2/ x̅ >1), respectively, suggesting that these forest ungulates dispersed contagiously. The social behavior of lowland anoa was solitary, whiereas Sulawesi warty pig formed groups of 2–5 individuals.