Nest-building orangutans must daily build safe and comfortable nest structures in the forest canopy and do this quickly and effectively using the branches that surround them. This study aimed to investigate the mechanical design and architecture of orangutan nests and determine the degree of technical sophistication used in their construction. We measured the whole nest compliance and the thickness of the branches used and recorded the ways in which the branches were fractured. Branch samples were also collected from the nests and subjected to three-point bending tests to determine their mechanical properties. We demonstrated that the center of the nest is more compliant than the edges; this may add extra comfort and safety to the structure. During construction orangutans use the fact that branches only break half-way across in "greenstick" fracture to weave the main nest structure. They choose thicker branches with greater rigidity and strength to build the main structure in this way. They then detach thinner branches by following greenstick fracture with a twisting action to make the lining. These results suggest that orangutans exhibit a degree of technical knowledge and choice in the construction of nests.
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http://dx.doi.org/10.1073/pnas.1200902109 | DOI Listing |
Primates
July 2019
Department of Physiological Ecology of Animals, University of Tübingen, Tübingen, Germany.
The past few decades have seen a burgeoning of scientific studies on great apes' use of nests for sleeping in the wild, as well as their nesting behavior and sleep in captivity. We review recent advances in knowledge of these topics, with the aim of promoting information exchange between people working in the field and with captive great apes. We trace developments in research into nest-building techniques in adults and immatures, factors that influence selection of general sleeping sites and specific locations, social aspects of sleep, postures, and nighttime activities.
View Article and Find Full Text PDFPLoS One
September 2012
Anthropological Institute and Museum, University of Zurich, Zurich, Switzerland.
Background: Several studies suggested great ape cultures, arguing that human cumulative culture presumably evolved from such a foundation. These focused on conspicuous behaviours, and showed rich geographic variation, which could not be attributed to known ecological or genetic differences. Although geographic variation within call types (accents) has previously been reported for orang-utans and other primate species, we examine geographic variation in the presence/absence of discrete call types (dialects).
View Article and Find Full Text PDFProc Natl Acad Sci U S A
May 2012
Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom.
Nest-building orangutans must daily build safe and comfortable nest structures in the forest canopy and do this quickly and effectively using the branches that surround them. This study aimed to investigate the mechanical design and architecture of orangutan nests and determine the degree of technical sophistication used in their construction. We measured the whole nest compliance and the thickness of the branches used and recorded the ways in which the branches were fractured.
View Article and Find Full Text PDFPLoS One
May 2010
Department of Anthropology and Graduate Group in Ecology, University of California Davis, Davis, California, USA.
Background: Conservationists frequently use nest count surveys to estimate great ape population densities, yet the accuracy and precision of the resulting estimates are difficult to assess.
Methodology/principal Findings: We used mathematical simulations to model nest building behavior in an orangutan population to compare the quality of the population size estimates produced by two of the commonly used nest count methods, the 'marked recount method' and the 'matrix method.' We found that when observers missed even small proportions of nests in the first survey, the marked recount method produced large overestimates of the population size.
Anim Cogn
April 2007
Department of Psychology, Glendon College of York University, 2275 Bayview Avenue, Toronto, ON, M4N 3M6, Canada.
We report an empirical study on leaf-carrying, a newly discovered nest-building technique that involves collecting nest materials before reaching the nest site. We assessed whether leaf-carrying by rehabilitant orangutans on Kaja Island, Central Kalimantan, owes to cultural influences. Findings derive from ca 600 h observational data on nesting skills and nesting associations in Kaja's 42 resident rehabilitants, which yielded 355 nests and 125 leaf-carrying cases by 34 rehabilitants.
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