Innovative composite tool use by Goffin's cockatoos (Cacatua goffiniana)

Abstract

Composite tool use (using more than one tool simultaneously to achieve an end) has played a significant role in the development of human technology. Typically, it depends on a number of specific and often complex spatial relations and there are thus very few reported cases in non-human animals (e.g., specific nut-cracking techniques in chimpanzees and capuchin monkeys). The innovative strategies underlying the innovation and spread of tool manufacture and associative tool use (using > 1 tools) across tool using animals is an important milestone towards a better understanding of the evolution of human technology. We tested Goffin's cockatoos on a composite tool problem, the 'Golf Club Task', that requires the use of two objects in combination (one used to control the free movement of a second) to get a reward. We demonstrate that these parrots can innovate composite tool use by actively controlling the position of the end effector and movement of both objects involved in a goal directed manner. The consistent use of different techniques by different subjects highlights the innovative nature of the individual solutions. To test whether the solution could be socially transmitted, we conducted a second study, which provided only tentative evidence for emulative learning. To our knowledge, this indicates that the cognitive preconditions for composite tool use have also evolved outside the primate lineage.

Figure 1

Basic apparatuses used: (A) Pre-experience apparatus with two insertion tubes; (B) Test Apparatus with frontal grid, lateral slits, and the central insertion hole.

Figure 2

Progress until reaching criterion or completing the minimum number of sessions, for the 3 solvers: (A) Figaro, (B) Fini, and (C) Pipin. Colors: black (failed due to reaching the time limit), grey (failed due to inactivity), yellow (solved by cheating), and blue (solved). The asterisk marks the criterion point. Y axis, time (seconds); X axis, sessions and trials.

Figure 3

Distinctive techniques and use of the tongue during insertions for the 3 solvers: (A) Figaro, (B) Fini, and (C) Pipin. (A) Figaro used his tongue to hold the rear end of the stick towards the inner upper beak, a balance between the position of the tongue and the head allows for movements of the stick (mostly vertical); (B) Fini held the stick by the front end, after inserting a short portion of the stick with her head movement and used her tongue a to push the stick with repeated thrusts; (C) Pipin grabbed and began the insertion with a leg grip and used his tongue to guide the stick towards the goal. After completing the insertion his technique changed to a beak hold similar to (A).