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The Ontogeny of Gap Crossing Behaviour in Bornean Orangutans (Pongo pygmaeus wurmbii).

Chappell J, Phillips AC, van Noordwijk MA, Mitra Setia T, Thorpe SK - PLoS ONE (2015)

Bottom Line: Our results suggest that gap crossing varies with both physical and cognitive development.Smaller individuals also crossed disproportionately large gaps relative to their size, by using support deformation.Our results suggest that orangutans acquire the full repertoire of gap crossing techniques, including the more cognitively demanding ones, before weaning, but adjust the frequency of the use of these techniques to their increasing body size.

View Article: PubMed Central - PubMed

Affiliation: School of Biosciences, University of Birmingham, Birmingham, United Kingdom.

ABSTRACT
For orangutans, the largest predominantly arboreal primates, discontinuous canopy presents a particular challenge. The shortest gaps between trees lie between thin peripheral branches, which offer the least stability to large animals. The affordances of the forest canopy experienced by orangutans of different ages however, must vary substantially as adult males are an order of magnitude larger in size than infants during the early stages of locomotor independence. Orangutans have developed a diverse range of locomotor behaviour to cross gaps between trees, which vary in their physical and cognitive demands. The aims of this study were to examine the ontogeny of orangutan gap crossing behaviours and to determine which factors influence the distance orangutans crossed. A non-invasive photographic technique was used to quantify forearm length as a measure of body size. We also recorded locomotor behaviour, support use and the distance crossed between trees. Our results suggest that gap crossing varies with both physical and cognitive development. More complex locomotor behaviours, which utilized compliant trunks and lianas, were used to cross the largest gaps, but these peaked in frequency much earlier than expected, between the ages of 4 and 5 years old, which probably reflects play behaviour to perfect locomotor techniques. Smaller individuals also crossed disproportionately large gaps relative to their size, by using support deformation. Our results suggest that orangutans acquire the full repertoire of gap crossing techniques, including the more cognitively demanding ones, before weaning, but adjust the frequency of the use of these techniques to their increasing body size.

No MeSH data available.


Related in: MedlinePlus

Illustrations to show the definition of the take-off support.The take-off support during the gap crossing behaviour ride was recorded as the support that deformed rather than the support the animal was holding on to. A) ride on trunk and B) ride on branch.
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pone.0130291.g001: Illustrations to show the definition of the take-off support.The take-off support during the gap crossing behaviour ride was recorded as the support that deformed rather than the support the animal was holding on to. A) ride on trunk and B) ride on branch.

Mentions: Every time focal orangutans were observed crossing between trees locomotor behaviour, support use and an estimate of the size of the gap crossed were recorded using a digital voice recorder to enable the observer (ACP) to watch and record simultaneously. Three types of support were distinguished: trunks (the primary members of trees), branches (all other tree elements including twigs and foliage), and lianas (vines with woody stems). This study recorded the support that was used to make the crossing. For modes that utilised support compliance the support that was deformed to make the crossing was recorded (see distinction in Fig 1a and 1b). For all other modes of locomotion, the last support that the subject made contact with on the take-off tree was recorded. Self-training in estimating horizontal distances in the forest was carried out extensively before the study and at monthly intervals during the study to ensure estimations were accurate. This was achieved by estimating horizontal distances at a range of heights in the canopy that could be subsequently quantified accurately at ground level.


The Ontogeny of Gap Crossing Behaviour in Bornean Orangutans (Pongo pygmaeus wurmbii).

Chappell J, Phillips AC, van Noordwijk MA, Mitra Setia T, Thorpe SK - PLoS ONE (2015)

Illustrations to show the definition of the take-off support.The take-off support during the gap crossing behaviour ride was recorded as the support that deformed rather than the support the animal was holding on to. A) ride on trunk and B) ride on branch.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4495978&req=5

pone.0130291.g001: Illustrations to show the definition of the take-off support.The take-off support during the gap crossing behaviour ride was recorded as the support that deformed rather than the support the animal was holding on to. A) ride on trunk and B) ride on branch.
Mentions: Every time focal orangutans were observed crossing between trees locomotor behaviour, support use and an estimate of the size of the gap crossed were recorded using a digital voice recorder to enable the observer (ACP) to watch and record simultaneously. Three types of support were distinguished: trunks (the primary members of trees), branches (all other tree elements including twigs and foliage), and lianas (vines with woody stems). This study recorded the support that was used to make the crossing. For modes that utilised support compliance the support that was deformed to make the crossing was recorded (see distinction in Fig 1a and 1b). For all other modes of locomotion, the last support that the subject made contact with on the take-off tree was recorded. Self-training in estimating horizontal distances in the forest was carried out extensively before the study and at monthly intervals during the study to ensure estimations were accurate. This was achieved by estimating horizontal distances at a range of heights in the canopy that could be subsequently quantified accurately at ground level.

Bottom Line: Our results suggest that gap crossing varies with both physical and cognitive development.Smaller individuals also crossed disproportionately large gaps relative to their size, by using support deformation.Our results suggest that orangutans acquire the full repertoire of gap crossing techniques, including the more cognitively demanding ones, before weaning, but adjust the frequency of the use of these techniques to their increasing body size.

View Article: PubMed Central - PubMed

Affiliation: School of Biosciences, University of Birmingham, Birmingham, United Kingdom.

ABSTRACT
For orangutans, the largest predominantly arboreal primates, discontinuous canopy presents a particular challenge. The shortest gaps between trees lie between thin peripheral branches, which offer the least stability to large animals. The affordances of the forest canopy experienced by orangutans of different ages however, must vary substantially as adult males are an order of magnitude larger in size than infants during the early stages of locomotor independence. Orangutans have developed a diverse range of locomotor behaviour to cross gaps between trees, which vary in their physical and cognitive demands. The aims of this study were to examine the ontogeny of orangutan gap crossing behaviours and to determine which factors influence the distance orangutans crossed. A non-invasive photographic technique was used to quantify forearm length as a measure of body size. We also recorded locomotor behaviour, support use and the distance crossed between trees. Our results suggest that gap crossing varies with both physical and cognitive development. More complex locomotor behaviours, which utilized compliant trunks and lianas, were used to cross the largest gaps, but these peaked in frequency much earlier than expected, between the ages of 4 and 5 years old, which probably reflects play behaviour to perfect locomotor techniques. Smaller individuals also crossed disproportionately large gaps relative to their size, by using support deformation. Our results suggest that orangutans acquire the full repertoire of gap crossing techniques, including the more cognitively demanding ones, before weaning, but adjust the frequency of the use of these techniques to their increasing body size.

No MeSH data available.


Related in: MedlinePlus