title: Aerial surveys give new estimates for orangutans in Sabah, Malaysia.
abstract: Great apes are threatened with extinction, but precise information about the distribution and size of most populations is currently lacking. We conducted orangutan nest counts in the Malaysian state of Sabah (North Borneo), using a combination of ground and helicopter surveys, and provided a way to estimate the current distribution and size of the populations living throughout the entire state. We show that the number of nests detected during aerial surveys is directly related to the estimated true animal density and that a helicopter is an efficient tool to provide robust estimates of orangutan numbers. Our results reveal that with a total estimated population size of about 11,000 individuals, Sabah is one of the main strongholds for orangutans in North Borneo. More than 60% of orangutans living in the state occur outside protected areas, in production forests that have been through several rounds of logging extraction and are still exploited for timber. The role of exploited forests clearly merits further investigation for orangutan conservation in Sabah.
authors.affiliation: Kinabatangan Orang-utan Conservation Project, Sandakan, Sabah, Malaysia. hutan1@tm.net.my <hutan1@tm.net.my>
authors.forename: Marc
authors.initials: M
authors.lastname: Ancrenaz
authors.forename: Olivier
authors.initials: O
authors.lastname: Gimenez
authors.forename: Laurentius
authors.initials: L
authors.lastname: Ambu
authors.forename: Karine
authors.initials: K
authors.lastname: Ancrenaz
authors.forename: Patrick
authors.initials: P
authors.lastname: Andau
authors.forename: Benoît
authors.initials: B
authors.lastname: Goossens
authors.forename: John
authors.initials: J
authors.lastname: Payne
authors.forename: Azri
authors.initials: A
authors.lastname: Sawang
authors.forename: Augustine
authors.initials: A
authors.lastname: Tuuga
authors.forename: Isabelle
authors.initials: I
authors.lastname: Lackman-Ancrenaz
mesh_terms: D000818:Animals; D003625:Data Collection; D017753:Ecosystem; D004777:Environment; D008296:Malaysia; D011148:Pongo pygmaeus; D011156:Population Density