title: Orangutan leaf-carrying for nest-building: toward unraveling cultural processes.
abstract: 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. Regional contrasts with 14 other communities (7 rehabilitant, 7 wild) indicated cultural influences on leaf-carrying on Kaja. Association data showed exceptional social learning opportunities for leaf-carrying on Kaja, with residents taking differential advantage of these opportunities as a function of development, experience, and social position. Juvenile males with basic nesting skills were most influenced by social input. Most (27) leaf-carriers had probably learned leaf-carrying when caged and 7 probably learned it on Kaja. Social priming was probably the main impetus to leaf-carrying on Kaja, by simply prompting observers to copy when leaf-carrying associates collected nesting materials, what they collected, and where they used their collected materials. Implications concern acquisition processes and ontogenetic schedules that orchestrate sets of features-needs or interests, cognitive abilities, social preferences-which enable cultural transmission.
authors.affiliation: Department of Psychology, Glendon College of York University, 2275 Bayview Avenue, Toronto, ON, M4N 3M6, Canada. arusson@gl.yorku.ca
authors.forename: Anne E
authors.initials: AE
authors.lastname: Russon
authors.forename: Dwi Putri
authors.initials: DP
authors.lastname: Handayani
authors.forename: Purwo
authors.initials: P
authors.lastname: Kuncoro
authors.forename: Agnes
authors.initials: A
authors.lastname: Ferisa
mesh_terms: D000818:Animals; D017753:Ecosystem; D005260:Female; D007214:Indonesia; D008297:Male; D009425:Nesting Behavior; D011148:Pongo pygmaeus / Q000502:physiology*; D014197:Trees