Mechanisms Underlying String-Pulling Behaviour in Green-Winged Macaw

<p>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.</p>