Age-Sex Class Differences in the Positional Behaviour of the Sumatran Orang-Utan ( Pongo pygmaeus abeli i ) in the Gunung Leuser National Park, Indonesia

Utrecht University, Utrecht, Utrecht, Netherlands
Folia Primatologica (Impact Factor: 0.89). 02/1986; 47(1):14-25. DOI: 10.1159/000156260
Source: PubMed


During a three-year field study of the socio-ecology of Sumatran orang-utans, their use of the canopy was investigated in the Gunung Leuser National Park, Indonesia. This paper concerns the positional behaviour of different age-sex classes of orang-utans. Adolescents and females with infants differed significantly from an adult male in the following respects: the use of locomotion types (more 'quadrumanous scrambling' and perhaps also 'quadrupedal walking' and less 'tree swaying'); substrate use during resting, and travelling and resting heights. We suggest that large body size restricts the travel route options in higher forest strata and necessitates the use of the lower stratum. Here, 'tree swaying' is an efficient method of progression, particularly for heavy animals. Mothers with infants are forced to travel in the lower zones as well. The fact that they return to a greater heights when they go to rest might suggest that they travel lower in spite of a greater predation risk.

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    • "In contrast, scapular shape should remain relatively constant throughout ontogeny in Homo, Pongo, and Hylobates—taxa not known to appreciably modify their locomotor behaviors (Gittins, 1983; Forssberg, 1985; Sugardjito and van Hooff, 1986; Cant, 1987; Thorpe and Crompton, 2005, 2006). "
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    ABSTRACT: Primate shoulder morphology has been linked with locomotor habits, oftentimes irrespective of phylogenetic heritage. Among hominoids, juvenile African apes are known to climb more frequently than adults, while orangutans and gibbons maintain an arboreal lifestyle throughout ontogeny. This study examined if these ontogenetic locomotor differences carry a morphological signal, which should be evident in the scapulae of chimpanzees and gorillas but absent in taxa that do not display ontogenetic behavioral shifts. The scapular morphology of five hominoid primates and one catarrhine outgroup was examined throughout ontogeny to evaluate if scapular traits linked with arboreal activities are modified in response to ontogenetic behavioral shifts away from climbing. Specifically, the following questions were addressed: 1) which scapular characteristics distinguish taxa with different locomotor habits; and 2) do these traits show associated changes during development in taxa known to modify their behavioral patterns? Several traits characterized suspensory taxa from nonsuspensory forms, such as cranially oriented glenohumeral joints, obliquely oriented scapular spines, relatively narrow infraspinous fossae, and inferolaterally expanded subscapularis fossae. The relative shape of the dorsal scapular fossae changed in Pan, Gorilla, and also Macaca in line with predictions based on reported ontogenetic changes in locomotor behavior. These morphological changes were mostly distinct from those seen in Pongo, Hylobates, and Homo and imply a unique developmental pattern, possibly related to ontogenetic locomotor shifts. Accordingly, features that sorted taxa by locomotor habits and changed in concert with ontogenetic behavioral patterns should be particularly useful for reconstructing the locomotor habits of fossil forms. Am J Phys Anthropol, 2013. © 2013 Wiley Periodicals, Inc.
    Full-text · Article · Aug 2013 · American Journal of Physical Anthropology
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    • "Terrestriality appears to be rare among Sumatran orangutans, possibly due to the presence of a large ground predator, the Sumatran tiger (Panthera tigris sumatrae ) [Cant, 1987; Manduell, pers. comm., April 2013; Sugardjito & van Hooff, 1986]. In contrast, terrestriality has been reported from several well‐studied Bornean orangutan populations. "
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    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 = 32) followed by flanged males (N = 26 records). P. p. morio represented the second most recorded primate (N = 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. Am. J. Primatol. 9999:1-10, 2013. © 2013 Wiley Periodicals, Inc.
    Full-text · Article · Jun 2013 · American Journal of Primatology
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    • "Theoretical predictions of the relationship between positional behavior and body mass (Cartmill and Milton, 1977), which imply that larger animals should suspend more than smaller ones, have not been borne out by the study of Sumatran orangutans (Cant, 1987b; Thorpe and Crompton, 2005). However, whereas in Sumatra orangutans rarely descend to the ground due to the presence of the Sumatran tiger (Panthera tigris sumatrae), (Sugardjito and van Hooff, 1986), in Borneo flanged males are known to spend a significant proportion of their time traveling on the ground (MacKinnon, 1974; Galdikas, 1979; Rodman, 1979; Tuttle, 1986), and sub-adult males and adolescent females have also been observed occasionally to travel substantial distances over the ground (Manduell, personal observations). How body size affects arboreal travel in a depauperate peat swamp forest is interesting as the prevalence of small trees, reduced availability of larger supports for travel, and possibly higher incidence of canopy gaps compared to pristine dipterocarp forest is likely to pose a greater challenge for such large bodied arboreal primates, suggesting that there may be a greater association between body size and locomotion than has been observed in Sumatra (Cant, 1987b; Thorpe and Crompton, 2005). "
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    ABSTRACT: This study examined the locomotor behavior of wild Bornean orangutans (P. p. wurmbii) in an area of disturbed peat swamp forest (Sabangau Catchment, Indonesia) in relation to the height in the canopy, age-sex class, behavior (feeding or traveling), and the number of supports used to bear body mass. Backward elimination log-linear modeling was employed to expose the main influences on orangutan locomotion. Our results showed that the most important distinctions with regard to locomotion were between suspensory and compressive, or, orthograde (vertical trunk) and pronograde (horizontal trunk) behavior. Whether orangutans were traveling or feeding had the most important influence on locomotion whereby compressive locomotion had a strong association with feeding, suspensory locomotion had a strong association with travel in the peripheral strata using multiple supports, whereas vertical climb/descent and oscillation showed a strong association with travel on single supports in the core stratum. In contrast to theoretical predictions on positional behavior and body size, age-sex category had a limited influence on locomotion. The study revealed that torso orthograde suspension dominates orangutan locomotion, concurring with previous studies in dipterocarp forest. But, orangutans in the Sabangau exhibited substantially higher frequencies of oscillatory locomotion than observed at other sites, suggesting this behavior confers particular benefits for traversing the highly compliant arboreal environment typical of disturbed peat swamp forest. In addition, torso pronograde suspensory locomotion was observed at much lower levels than in the Sumatran species. Together these results highlight the necessity for further examination of differences between species, which control for habitat.
    Full-text · Article · Jul 2011 · American Journal of Physical Anthropology
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