In the wild, chimpanzees are proficient hunters. Their favourite prey, red colobus monkeys, are hard to catch because they are faster than chimpanzees and also lighter, so they can escape using parts of the tree canopy that chimpanzees can’t access. Chimpanzees are able to overcome these difficulties by working together in groups to surround and capture the red colobus. They even seem to deliberately take on different roles, with some individual chimpanzees chasing the monkeys, while others block potential escape routes and yet others lie in wait to ambush fleeing prey when they come near. In other words, chimpanzees seem to hunt cooperatively.

However, we do not yet have proof that this is the case. A possible alternative is that groups of chimpanzees are hunting simultaneously but independently. They might not be thinking about what their fellow hunters are doing, and how their actions affect the prey’s decisions: they may just be reacting to the moment-to-moment movements of the monkeys, and what look like ‘ambushing’ or ‘blocking’ tactics could just be byproducts of several chimpanzees hunting in parallel.

In this experiment, we are trying to discover whether chimpanzees consider the presence of another hunter using our virtual environment on a touchscreen computer! The subjects need to touch the screen to bring themselves close enough to the virtual boar prey to collide with it. Then they will be rewarded with fruit. But the boar is fast-moving and quickly reacts to the subject’s approach, so it is very hard for them to catch it alone. However, there is also another hunter within the game, a virtual ape, who can help the subject!

The question is, can the chimpanzees take account of the location of the other ape, and can they use this to guide their own movements so that they corner the prey?