Animal Cognition

, 9:317 | Cite as

A New Caledonian crow (Corvus moneduloides) creatively re-designs tools by bending or unbending aluminium strips

  • Alex A. S. WeirEmail author
  • Alex Kacelnik
Original Article


Previous observations of a New Caledonian crow (Corvus moneduloides) spontaneously bending wire and using it as a hook [Weir et al. (2002) Science 297:981] have prompted questions about the extent to which these animals ‘understand’ the physical causality involved in how hooks work and how to make them. To approach this issue we examine how the same subject (“Betty”) performed in three experiments with novel material, which needed to be either bent or unbent in order to function to retrieve food. These tasks exclude the possibility of success by repetition of patterns of movement similar to those employed before. Betty quickly developed novel techniques to bend the material, and appropriately modified it on four of five trials when unbending was required. She did not mechanically apply a previously learned set of movements to the new situations, and instead sought new solutions to each problem. However, the details of her behaviour preclude concluding definitely that she understood and planned her actions: in some cases she probed with the unmodified tools before modifying them, or attempted to use the unmodified (unsuitable) end of the tool after modification. Gauging New Caledonian crows’ level of understanding is not yet possible, but the observed behaviour is consistent with a partial understanding of physical tasks at a level that exceeds that previously attained by any other non-human subject, including apes.


New Caledonian crows Tool use Tool modification Planning Folk physics 



We are grateful to Jackie Chappell, Ben Kenward, Christian Rutz, Lucas Bluff, Jo Wimpenny, and Stephen Barlow, for many discussions about experimental design and interpretation. David Wilson looked after Betty through her life in Oxford with affection and efficiency. Thanks to Charlotte Burn and three anonymous referees for helpful comments on the manuscript. David Palmer and Tony Price helped design and build the experimental room and its entrance-control mechanism. The experiments described here comply with all applicable laws of the United Kingdom, where they were carried out. This work was funded by a scholarship from the Wellcome Trust to AASW and BBSRC grant BB/C517392/1 to AK.

Supplementary material

10071_2006_52_MOESM1_ESM.pdf (188 kb)
Table S1: Trial-by-trial description of Experiment 1. ‘Trial code’ summarises the result of the trial (O = own tool; U = unmodified strip; M = modified strip; f = failure (to get food); s = success). ‘Duration’ is the length of time from first interacting with the apparatus to retrieving food (minutes : seconds). ‘Tool dimensions’ gives the length and width of the tool at the start of the trial (mm).
10071_2006_52_MOESM2_ESM.pdf (79 kb)
Table S2: Trial-by-trial description of Experiment 2. Columns as above, except ‘Success’ which indicates whether the subject successfully retrieved the food (y = yes; n = no)
10071_2006_52_MOESM3_ESM.pdf (88 kb)
Table S3: Trial-by-trial description of Experiment 3. Columns as above.
10071_2006_52_MOESM4_ESM.pdf (8.4 mb)
Fig. S4: Final tool shapes in Experiment 1. In each photo, the number refers to the trial on which the tool was made, and the scale bar represents 3 cm.

Video S5: Video of Trial 3, Experiment 1. This shows the first trial on which the subject modified the aluminium strips. See Table S1 for a detailed description of the trial. Format: Windows Media Video; duration: 6min 45s.

Video S6: Video of Trial 32, Experiment 1. This shows an example of the ‘bend’ technique that the subject developed for modifying the aluminium strips, towards the end of the experiment. See Table S1 for a detailed description of the trial. Format: Windows Media Video; duration: 21s.

Video S7: Video of Trial 3, Experiment 3. This shows the first time the subject unbent the aluminium strip. After food-retrieval, the unbending action is replayed in slow-motion. The clip starts 4min 7s into the trial, after the subject had already probed with the tool 4 times (for a total of 16s), but before she had modified it. After modification, there is a break in the clip during which the subject probed for the food 4 times (for 50s), twice with each end of the tool. See Table S3 for a detailed description of the trial. Format: Windows Media Video; duration: 55s.

Video S8: Video of Trial 4, Experiment 3. On this trial the subject unbent the tool using a similar action to Trial 3. As with Video S7, the clip ends with a replay of the unbending action in slow-motion. The clip starts 3min 15s into the trial, after the subject had already probed with the tool 7 times (for 37s), but before she had modified it. See Table S3 for a detailed description of the trial. Format: Windows Media Video; duration: 51s.


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Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  1. 1.Department of ZoologyOxfordUK

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