 Shaping was then used in a delay task, with the partner released after one second, then two, and gradually up to 25 seconds later than the first bird.The birds managed to wait for a partner between 74% to 91% of test trials, including success at 65 seconds delay, longer than any other animal of any species had been tested for.To assess if this success could be explained by the learning of a combination of cues, such as seeing a partner while feeling tension on the string, or by a proper understanding of cooperation, the researchers randomly gave the keas a set-up they could solve alone or one in which they needed to cooperate with a delayed partner.