More shots from Perth Zoo's wonderful orangutan exhibit. These apes are incredibly intelligent and it would be terrible to let them sit in an enclosure with nothing to stimulate them. So the zoo runs a "behavioural enrichment" programme, which essentially means that they leave plenty of toys, items and challenges to keep the orangutans mentally engaged. Here's a sequence of a female making use of one such opportunity, and demonstrating the orangutan's prowess with tools.

She grabs a sturdy stick from the grounds...

and walks over to a metal tray, where a keeper has hidden something. She fishes around for the treat. Sometimes, they will take the stick out and lick it to see what's buried.

Nearly there...

Got it! A biscuit. OM NOM NOM. Meanwhile, baby watches intently, probably picking up a few tricks or two.