Innovative pandanus-tool folding by New Caledonian crows
Gavin R. Hunt A D , Jawad Abdelkrim B , Michael G. Anderson C , Jennifer C. Holzhaider A , Amy J. Marshall B , Neil J. Gemmell B and Russell D. Gray AA Department of Psychology, University of Auckland, Auckland 1142, New Zealand.
B Molecular Ecology Laboratory, Biological Sciences, University of Canterbury, Christchurch, New Zealand.
C Ecology and Conservation Group, Institute of Natural Resources, Albany Campus, Massey University, Auckland, New Zealand.
D Corresponding author. Email: grhunt@hotmail.com
Australian Journal of Zoology 55(5) 291-298 https://doi.org/10.1071/ZO07048
Submitted: 5 September 2007 Accepted: 9 November 2007 Published: 8 February 2007
Abstract
The ratcheting of evolutionary innovations over time has enabled humans to produce complex technology. This process requires (1) technological innovations, (2) the accurate transmission of innovations by social learning, and (3) the faithful maintenance of new technology by its standardised reproduction. Although nonhuman primates are good behavioural innovators, there is no evidence that they have evolved cumulative technology. It has been previously suggested that New Caledonian crows have made cumulative changes to their pandanus tool manufacture. However, technological innovation by individual New Caledonian crows in the wild had not been observed. Here, we report that two distantly related male crows at the same location have a novel way of using pandanus tools by first folding them into a boomerang-like shape. The fine manipulation to fold tools was highly routinised and its two main manipulatory components (direction of head movement and holding technique) were exclusively lateralised. As a consequence the fold arrangement was invariable irrespective of a tool’s position before folding. The males’ tool-folding confirms that New Caledonian crows have a disposition to routinise and lateralise complex sequences of manipulatory actions. Such a disposition may facilitate the evolution of cumulative technology because it can act to standardise the reproduction of a technological innovation.
Acknowledgements
We thank W. Wadrobert for access to his family’s land, D. Houmbouy for permission to work on Maré and M. Sibley for preparing DVDs. MGA filmed the free-living male and JCH filmed the captive male. M. Corballis and A. Taylor provided helpful comments on the manuscript. Our work was carried out under University of Auckland Animal Ethics Committee approval R375 and complied with the laws of New Caledonia. This research was funded by a New Zealand Marsden Fund grant (RDG and GRH).
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