| dc.description.abstract | Orangutans (Pongo) are the largest arboreal mammals and the only great apes that spend most of
their life in the trees. Wild orangutans employ a great diversity of locomotion behaviours when
traversing the canopy and are rarely on the ground. However, in captivity orangutans are known to
spend less time on movement and being above-ground then their wild counterparts. Additionally,
captive orangutans most commonly walk around their enclosure, while wild orangutans rarely walk
and predominantly use suspensory locomotion to move across the canopy. Stimulating natural
locomotion behaviour can benefit captive species significantly, especially the energy efficient
orangutan, as their low metabolic rates make them prone to obesity. Yet, it remains poorly
understood which enclosure designs can be used to stimulate natural locomotion in captive
orangutans.
Therefore, in this study different naturalistic enclosure designs were compared to study both the
quantity and quality of locomotion of orangutans in these enclosures. Ten Bornean orangutans
(Pongo pygmaeus) were focally observed in three enclosure types at Apenheul Primate Park
(Apeldoorn, the Netherlands) and Allwetterzoo (Münster, Germany), both inside and outside. Mainly
enclosure types containing many large horizontal trunks were compared with enclosures containing
large amounts of ropes.
Regarding the quantity of locomotion, no differences were found between enclosures and
orangutans in all enclosures moved less than their wild counterparts. However, for the quality of
locomotion, slight differences were detected between the enclosure types. Mainly, orangutans used
natural and challenging locomotion types, such as suspensory locomotion and climbing, somewhat
more frequently in an inside enclosure with a high density of vertically aligned ropes. Our findings
indicate that enclosure design does affect the types of locomotion shown by captive Bornean
orangutans. Importantly, increasing the number of thin flexible substrates seems to somewhat
increase the occurrence of more natural locomotion types. However, natural rates for the total
quantity of locomotion, as well as the occurrence of natural locomotion types were not fully attained
in any of the enclosure types studied. Therefore, while we recommend increasing the number of thin
flexible substrates in captivity, further efforts are needed to stimulate orangutans towards natural
locomotion patterns. | |
