Kea (Nestor notabilis) and the ephemeral reward task: Success and hurdles explored.

The ephemeral reward task (ERT), employed in animal cognition research, appears deceptively straightforward but seems to be counterintuitive for many lab animals. Our study explored the performance of kea (Nestor notabilis) on this task, in two different setups based on previously used methodologies: one with direct visible reward presentation, and one with non-visible rewards plus a spatial component. Additionally, we investigated their ability, using the same setups, to choose two pieces of reward as opposed to one in a basic quantity discrimination task (QDT), as this is the outcome of the ERT meant to motivate choosing optimally. The results showed that a greater proportion of kea successfully solved the ERT when the rewards were directly visible, compared to when they were non-visible. Likewise, in the QDT, the kea exhibited a preference for selecting two pieces of reward over one, with higher success rates observed in the setup with visible rewards. More kea solved the QDT than the ERT. However, not all subjects successfully solved the QDT within the standard 100 trials, and none did so spontaneously from the first session; suggesting that the presence of two outcomes alone is not the only hurdle for subjects to overcome.