The right tool for the job: what strategies do wild New Caledonian crows use?
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New Caledonian crows Corvus moneduloides (NC crows) display sophisticated tool manufacture in the wild, but the cognitive strategy underlying these skills is poorly understood. Here, we investigate what strategy two free-living NC crows used in response to a tool-length task. The crows manufactured tools to extract food from vertical holes of different depths. The first tools they made in visits were of a similar length regardless of the hole depth. The typical length was usually too short to extract food from the deep holes, which ruled out a strategy of immediate causal inference on the first attempt in a trial. When the first tool failed, the crows made second tools significantly longer than the unsuccessful first tools. There was no evidence that the crows made the lengths of first tools to directly match hole depth. We argue that NC crows may generally use a two-stage heuristic strategy to solve tool problems and that performance on the first attempt in a trial is not necessarily the ‘gold standard’ for assessing folk physics.
KeywordsCognition Folk physics New Caledonian crows Tool manufacture and use
We thank Emile Hautcoeur for access to his land at Sarraméa. Staff in the Political Section of the provincial administration on Maré provided valuable help with access to forest and William Wadrobert kindly allowed us to work on his family's land in Wabao District. Daniel Houmbouy (Province des Iles Loyauté) gave us permission to work on Maré, and Etienne DuTailly provided us with accommodation and assistance in Nouméa. We thank Mick Sibley for preparing DVD versions of the footage and Michael Corballis and Alex Taylor for helpful comments on the manuscript. This research was funded by an Auckland University Emerging Researchers Grant (G.R.H.), the New Zealand Marsden Fund (R.D.G. and G.R.H.) and a Thomas J. Watson Fellowship (R.B.R.). The research reported in this paper was approved by the University of Auckland Animal Ethics committee (approval #R172). We thank Shige Watanabe and Ludwig Huber for inviting us to participate in the Animal Logic symposium in Vienna, and Alex Weir and Alex Kacelnik for an exchange of crow manuscripts submitted to this volume.
- Emery NJ (2006) Cognitive ornithology: the evolution of avian intelligence. Phil Trans R Soc B 361:23–43Google Scholar
- Hunt GR, Gray RD (2004a) The crafting of hook tools by wild New Caledonian crows. Proc R Soc Lond B (Suppl) 271:S88–S90Google Scholar
- Martin GR, Katzir G (1999b) Visual fields, foraging and binocularity in birds. In: Adams NJ, Slotow RH (eds) Proceedings of the 22nd international ornithological congress. BirdLife South Africa, pp 2711–2728Google Scholar
- McGrew WC (1992) Chimpanzee material culture: implications for human evolution. Cambridge University Press, Cambridge, UKGoogle Scholar
- Millikan GC, Bowman RI (1967) Observations on Galápagos tool-using finches in captivity. Living Bird 6:23–41Google Scholar
- Povinelli DJ (2000) Folk physics for apes: the chimpanzee's theory of how the world works. Oxford University Press, OxfordGoogle Scholar
- Sterelny K (2003) Thought in a hostile world: the evolution of human cognition. Blackwell, OxfordGoogle Scholar
- Thouless CR, Fanshawe JH, Bertram CR (1987) Egyptian vultures Neophron percnopterus and Ostrich Struthio camelus eggs: the origins of stone-throwing behaviour. Ibis 131:9–15Google Scholar
- Tomasello M (1999) The cultural origins of human cognition. Harvard University Press, Cambridge, MAGoogle Scholar
- Tomasello M, Call J (1997) Primate cognition. Oxford University Press, New YorkGoogle Scholar
- Visalberghi E, Limongelli L (1996) Acting and understanding: tool use revisited through the minds of capuchin monkeys. In: Russon AE, Bard KA, Parker ST (eds) Reaching into thought: the minds of the great apes. Cambridge University Press, Cambridge, UK, pp 57–79Google Scholar
- Watanabe S, Huber L (2006) Animal logics: decisions in the absence of human language. Anim Cogn DOI: 10.1007/s10071-006-0043-6Google Scholar
- Weir AAS, Kacelnik A (2006) New Caledonian crows (Corvus moneduloides) creatively re-design tools by bending or unbending metal strips according to needs. Anim Cogn DOI: 10.1007/s10071-006-0052-5Google Scholar
- Weir AAS, Kenward B, Chappell J, Kacelnik A (2004) Lateralization of tool use in New Caledonian crows (Corvus moneduloides). Proc R Soc Lond B (Suppl) 271:S344–S346Google Scholar