Mechanisms underlying string-pulling behaviour in green-winged macaws

in Behaviour
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The string-pulling test is a classic test of physical cognition which is thought to examine an animal’s understanding of means-end comprehension, but may also result from trial and error learning. Here, we presented Green-winged macaws (Ara chloroptera) with a standard pull-up, and an alternative, pull-down, string pulling test to better understand the processes involved. Birds were divided into two groups: the experimental group were presented with the classic pull-up test and, upon completion, with the pull-down test, while the control group were only presented with the pull-down test. Six experimental birds solved the pull-up test, although none successfully completed the pull-down test; however, birds from the experimental group made significantly more pull-down actions than those from the control group. Together with previous findings on string-pulling behaviour in green-winged macaws, the results from the present study suggest that string-pulling behaviour in this species does not involve means-end understanding.

Mechanisms underlying string-pulling behaviour in green-winged macaws

in Behaviour



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  • View in gallery

    (a) The pull-up apparatus, in which birds were required to pull the string up to retrieve reward. (b) The pull-down apparatus, in which birds had to pull the string down for the reward. Not drawn to scale.

  • View in gallery

    Performance of the six successful parrots between the first and last sessions of pull-up training, in terms of (a) the time taken to complete the training trials and (b) the number of times the string was dropped. Differences between groups in the pull-down task for (c) the number of pulls at the string and (d) the number of times birds reached for the string. The performance of six parrots of the control group and seven parrots of the experimental group is shown in panels (c) and (d).

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