Video: Parrot unlocks box

Klepto keas (Image: Eye Ubiquitous/Rex Features)

Kea parrots are renowned thieves in their native New Zealand, and with good reason – even a complicated sequence of locks can’t foil them.

Hiromitsu Miyata of Kyoto University in Japan first presented keas with boxes of food secured with up to three bolts. The parrots managed to open all of them, so he made the tasks harder. The most challenging set-up involved two bolts blocking each other such that one needed to be slid open before the second would release.

Miyata found that the keas cracked this problem faster if …