PENDUGAAN POPULASI ORANGUTAN (Pongo abelii Lesson 1827) BERDASARKAN SARANG DI CAGAR ALAM SIPIROK, SUMATERA UTARA

Abstract

Currently, Pongo abelii Lesson 1827 populations in their natural habitat are in endangered and on the verge of extinction. The objective of this research was to obtain information on the characteristics of nests and to estimate the population of orangutans in Sipirok Nature Reserve, North Sumatra. Data collection has been conducted for four months, from April to July 2010. Observations of P. abelli were performed using a combination of line transect method by counting the number of nests. Each transect was made along the 1 km transect line with total number of 29 transects. Placement of transects was stratified based on different habitat types. P. abelli density was estimated by nest characteristics. The length of the nest was between 60-150 cm and age class including the class C (42%) and D (31%). Characteristics of the nest were very difficult to be used to determine the age structure of orangutans. The average density of P. abelli in Sipirok Nature Reserve were 0.47 individuals/km 2 or with a presume of population between 22-40 individuals. Programs to increase the population could be done through the restoration, especially around Rambassiasur enclave.