From the "sticker" to the "seed" slide: Challenges testing concurrent tooling in Goffin's cockatoos.

Although Goffin's cockatoos (Cacatua goffiniana) can innovate the use of two tools in a sequence, it is unknown whether they have the capacity to use two tools concurrently, which supposes a higher level of complexity in order to manage the spatial relations between objects. According to tooling theory, such a high degree of spatial management is beyond the capacity of nonhuman animals. In this experiment, we set out to test this prediction with a species that has exhibited some of the most complex tool use in the animal kingdom, the Goffin's cockatoo. We used a concurrent tool use task previously designed for primary school children (the "sticker slide"), which was found to be challenging even for nine-year-old children. Despite none of the cockatoos successfully innovating the "seed slide" task, they still exhibited several innovative and explorative combinatory behaviours. Their failure appears to be due more to the apparatus design, which was not compatible with their morphology and ecological predispositions, as well as possible fixedness leading them to primarily focus on the top of the two possible tool openings, a bias also observed in some of the young children on the same task.