Abstract Diploma Thesis Stefan Merker

The Influence of Traditional Land-use Forms on Population Densities of the Dian's Tarsier Tarsius dianae in the Rain Forest of Sulawesi

Centre for Nature Conservation, Georg-August University Goettingen, Germany

From June to November 1998, a field study on the Dian's tarsier's tolerance of human influences was conducted at Kamarora, Lore Lindu National Park, Sulawesi. Tarsier densities were taken as a measure of well-being. All sleeping trees in four 8 - 24 ha plots of rainforest with differing human influences were located and the distances to their three nearest neighbours were recorded. The identification of the sleeping sites was based on the morning duets frequently performed around dawn and the subsequent focal following of the tarsiers. In each of the differently sized plots, 10 or 11 groups were counted. The three nearest neighbours of the central seven or eight of these groups were determined and the distances between the trees were measured. The smallest distances between sleeping sites were found in an area interspersed with small (< 0.5 ha) coffee and cocoa plantations, but without rattan, bamboo or wood extraction. On average, the distance between groups in this area is 80 m, which corresponds to a density of 15.6 gr./10 ha. In primary forest, the tarsier families sleep, on average, 86 m apart from each other (13.6 gr./10 ha). The separation between sleeping trees is greatest in a part of the forest dominated by regular small-scale logging, but without any agroforestry (133 m, 5.6 gr./10 ha). An intermediate density was found in an area where both of the mentioned human influences were combined (108 m, 8.5 gr./10 ha). Hence tarsiers make distinctions in their acceptance of human activities. The preference of plantations can be explained by a high abundance of insects, the favourite tarsier food. The high degree of disturbance as well as the reduction of locomotor supports and potential sleeping sites is thought to be responsible for the low densities in the logging areas. The positive effect of agroforestry may balance the negative impact of wood extraction to some extent, and should be taken into account when designing conservation strategies.

Supported by the German National Academic Foundation and the German Primatological Society.