dc.description.abstract | Aside from anecdotal evidence, terrestriality in orangutans (Pongo spp.) has not been quantified or
subject to careful study and important questions remain about the extent and contexts of terrestrial
behavior. Understanding the factors that influence orangutan terrestriality also has significant
implications for their conservation. Here we report on a camera trapping study of terrestrial behavior in
the northeastern Bornean orangutan, Pongo pygmaeus morio, in Wehea Forest, East Kalimantan,
Indonesia. We used 78 non‐baited camera traps set in 43 stations along roads, trails, and at mineral licks
(sepans) to document the frequency of orangutan terrestriality. Habitat assessments were used to
determine how terrestrial behavior was influenced by canopy connectivity. We compared camera
trapping results for P. p. morio to those for a known terrestrial primate (Macaca nemestrina), and another
largely arboreal species (Presbytis rubicunda) to assess the relative frequency of terrestrial behavior by P.
p. morio. A combined sampling effort of 14,446 trap days resulted in photographs of at least 15 individual
orangutans, with females being the most frequently recorded age sex class (N ¼ 32) followed by flanged
males (N ¼ 26 records). P. p. morio represented the second most recorded primate (N ¼ 110 total records)
of seven primate species recorded. Capture scores for M. nemestrina (0.270) and P. p. morio (0.237) were
similar and almost seven times higher than for the next most recorded primate, P. rubicunda (0.035). In
addition, our results indicate that for orangutans, there was no clear relationship between canopy
connectivity and terrestriality. Overall, our data suggest that terrestriality is relatively common for the
orangutans in Wehea Forest and represents a regular strategy employed by individuals of all age sex
classes. As Borneo and Sumatra increasingly become characterized by mixed‐use habitats, understanding
the ecological requirements and resilience in orangutans is necessary for designing optimal
conservation strategies. | en_US |