i ORANGUTAN NESTING PREFERENCES IN A DISTURBED TROPICAL DEEP-PEAT SWAMP FOREST, CENTRAL KALIMANTAN, INDONESIA.

The primary aim of the study was to identify tree and habitat preferences essentially important in orangutan nesting behaviour within a disturbed swamp forest habitat. The main objective being to identify the desires and needs of the population with regard to nesting areas and to shed new light on the understudied area of orangutan nesting behaviour. The study was carried out on a previously unstudied wild population of southern race Bornean orangutans (Pongo pygmaeus wurmbii) in the newly designated Sabangau National Park of Central Kalimantan, Indonesia. The hypothesis under investigation was that orangutans possess distinct nesting preferences, which vary according to the sex and maturity of the nest builder. Preferences were predicted to be based on individual tree and site attributes, whereby orangutans purposefully seek the best available habitat for nesting. Recently habituated, wild orangutans were followed from nest to nest over a six-month period; architectural and structural variables of nest trees and nesting sites were recorded. 74 nests from twenty-one individuals were investigated, with additional data from OuTrop nest density surveys increasing available data to 279 nest trees. Nesting behaviour was found to be species specific with distinct preferences discovered for each age / sex class, enabling multivariate analysis to predict the age / sex class of a nest builder by following a set of simple rules based on deep-ended variables identified in one-way analysis. ii Acknowledgements I would like to extend heartfelt thanks to my field supervisors Simon Husson and Hele