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dc.contributor.authorKlump, Barbara Christina
dc.contributor.authorSugasawa, Shoko
dc.contributor.authorSt Clair, James
dc.contributor.authorRutz, Christian
dc.date.accessioned2015-11-18T16:10:03Z
dc.date.available2015-11-18T16:10:03Z
dc.date.issued2015-11-18
dc.identifier.citationKlump , B C , Sugasawa , S , St Clair , J & Rutz , C 2015 , ' Hook tool manufacture in New Caledonian crows : behavioural variation and the influence of raw materials ' , BMC Biology , vol. 13 , 97 . https://doi.org/10.1186/s12915-015-0204-7en
dc.identifier.issn1741-7007
dc.identifier.otherPURE: 225527565
dc.identifier.otherPURE UUID: 578b924c-bce0-4a72-90c1-61eedaf3d736
dc.identifier.otherScopus: 84947417939
dc.identifier.otherORCID: /0000-0003-4452-1177/work/58531625
dc.identifier.otherORCID: /0000-0001-5187-7417/work/60427576
dc.identifier.otherWOS: 000365271400001
dc.identifier.urihttp://hdl.handle.net/10023/7815
dc.descriptionFunding: BBSRC grants BB/G023913/1 and BB/G023913/2en
dc.description.abstractBackground: New Caledonian crows use a range of foraging tools, and are the only non-human species known to craft hooks. Based on a small number of observations, their manufacture of hooked stick tools has previously been described as a complex, multi-stage process. Tool behaviour is shaped by genetic predispositions, individual and social learning, and/or ecological influences, but disentangling the relative contributions of these factors remains a major research challenge. The properties of raw materials are an obvious, but largely overlooked, source of variation in tool-manufacture behaviour. We conducted experiments with wild-caught New Caledonian crows, to assess variation in their hooked stick tool making, and to investigate how raw-material properties affect the manufacture process. Results: In Experiment 1, we showed that New Caledonian crows’ manufacture of hooked stick tools can be much more variable than previously thought (85 tools by 18 subjects), and can involve two newly-discovered behaviours: ‘pulling’ for detaching stems and bending of the tool shaft. Crows’ tool manufactures varied significantly: in the number of different action types employed; in the time spent processing the hook and bending the tool shaft; and in the structure of processing sequences. In Experiment 2, we examined the interaction of crows with raw materials of different properties, using a novel paradigm that enabled us to determine subjects’ rank-ordered preferences (42 tools by 7 subjects). Plant properties influenced: the order in which crows selected stems; whether a hooked tool was manufactured; the time required to release a basic tool; and, possibly, the release technique, the number of behavioural actions, and aspects of processing behaviour. Results from Experiment 2 suggested that at least part of the natural behavioural variation observed in Experiment 1 is due to the effect of raw-material properties. Conclusions: Our discovery of novel manufacture behaviours indicates a plausible scenario for the evolutionary origins, and gradual refinement, of New Caledonian crows’ hooked stick tool making. Furthermore, our experimental demonstration of a link between raw-material properties and aspects of tool manufacture provides an alternative hypothesis for explaining regional differences in tool behaviours observed in New Caledonian crows, and some primate species.
dc.format.extent15
dc.language.isoeng
dc.relation.ispartofBMC Biologyen
dc.rights© 2015 Klump et al. Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stateden
dc.subjectConstruction behaviouren
dc.subjectCorviden
dc.subjectCorvus Moneduloidesen
dc.subjectExtractive foragingen
dc.subjectHooken
dc.subjectMaterial cultureen
dc.subjectSocial learningen
dc.subjectStone toolsen
dc.subjectTool manufactureen
dc.subjectTool useen
dc.subjectQH301 Biologyen
dc.subject.lccQH301en
dc.titleHook tool manufacture in New Caledonian crows : behavioural variation and the influence of raw materialsen
dc.typeJournal articleen
dc.description.versionPublisher PDFen
dc.contributor.institutionUniversity of St Andrews.School of Biologyen
dc.contributor.institutionUniversity of St Andrews.Centre for Social Learning & Cognitive Evolutionen
dc.contributor.institutionUniversity of St Andrews.Centre for Biological Diversityen
dc.identifier.doihttps://doi.org/10.1186/s12915-015-0204-7
dc.description.statusPeer revieweden


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