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Documenting the ways in which organisms physically move through space and the influences of habitat structure on their movement and posture are fundamental to understanding their spatial ecology. Movement ecology is thus a significant influence on animal cognition, morphology, diet, group structure, etc. Evidence to date demonstrates that orangutans of different species (Pongo abelii, P. wurmbii) living in similar habitats exhibit positional behavior more similar to each other than to conspecifics in disparate habitats. Therefore, it is a reasonable hypothesis that orangutan positional behavior is a function of habitat rather than morphological constraints. Here, we test this hypothesis by examining the positional behavior of orangutans living in Gunung Palung National Park in West Kalimantan, Indonesia, a primary forest mosaic composed of seven distinct habitats. We use 33,358 instantaneous scan samples collected every 5 minutes during full day follows of habituated adult orangutans (N=27) to examine postural behavior, locomotor modes, and structure use with a null hypothesis of no differences in positional behavior or support use profiles between habitats. We found significant differences in the profiles of orangutan postural behavior (G=216.2, p<0.001), locomotor behavior (G=45.34, p<0.001), and support use (G=137.8, p<0.001) in 5 distinct habitats within Gunung Palung National Park. Orangutans within the same population move through and use distinct habitats in different ways. This underscores the role of local ecology in structuring organisms’ space use as well as the importance of behavioral plasticity to primates’ movement ecology. Funding: National Science Foundation (BCS-1638823, BCS-0936199); National Geographic Society; US Fish and Wildlife (F15AP00812, F12AP00369, 98210-8-G661); Leakey Foundation; Disney Wildlife Conservation Fund; Wenner-Gren Foundation; Nacey-Maggioncalda Foundation 

Wild Bornean orangutans experience fluctuations in the availability of their preferred food, fruit. During periods of low fruit availability, orangutans rely on fallback foods which are expected to be higher in fiber and generally lower in free simple sugars. However, it is not clear whether there is a consistent relationship between fiber content and the content of other nutrients. Here, we examine acid detergent fiber (ADF) content of 101 plant foods consumed by orangutans in Gunung Palung National Park, West Kalimantan, Indonesia, and the correlation between ADF and other important plant macronutrients. Samples were collected during full-day behavioral follows between 1994-2001. Samples were analyzed in triplicate through a reflux apparatus, which quantified ADF proportion by weight. An ANOVA revealed significant differences between ADF concentrations of different plant parts (F(5)=20.89, p < 0.001). Post-hoc analyses (α= 0.005) determined that bark had a significantly higher ADF concentration than pulp and seeds (p<0.001), leaves had a significantly higher ADF concentration than seeds (p<0.001), and whole fruit had a significantly higher ADF concentration than pulp or seeds (p<0.001). We found a negative correlation between free simple sugar concentration and ADF (R = -0.63, p<0.001). However, there was no significant correlation between ADF and protein (R=-0.14, p=0.17) or lipid (R 0.134, p=0.19) content. Our findings corroborate work showing that bark and leaves are particularly high in ADF. However, they underscore the fact that determining dietary quality is complex, and that food items that are high in fiber may still be good sources of non-carbohydrate energy. National Science Foundation (BCS-1638823, BCS-0936199, 1540360, 9414388); National Geographic Society; US Fish and Wildlife (F15AP00812, F12AP00369, 98210-8-G661); Leakey Foundation; Disney Wildlife Conservation Fund; Wenner-Gren Foundation; Nacey-Maggioncalda Foundation; Conservation, Food and Health