Visitors to Pretoria Zoo may be forgiven, if after a visit to the primates, they suspect monkey business of a different kind.
Cardboard boxes filled with shredded paper placed in enclosures will appear bizarre to most, but for the zoo's primates, it's serious stuff.
Says Robynn Ingle, 30, head of the zoo's Environmental Enrichment Programme: "The programme was started to encourage the animal's natural behaviour by using various interactive materials."
Shredded paper appears to be the answer. "The idea behind the shredded paper is that it can be used as ground litter where food can be hidden," she said.
Primates conservator Elsie Briedenhann, 25, says the food is hidden in the shredded paper to encourage the primates to forage for their food. The paper and food are hidden in cardboard boxes to challenge the animals further.
"This encourages natural foraging behaviour and helps with their social interaction at feeding time."
On Thursday the zoo demonstrated the effectiveness of the simple feeding device.
The Lion-tailed Macaques from Asia, attacked the boxes with gusto. In no time, the boxes were torn open and each macaque foraged for bits of fruit and vegetables.
The African Hamadryas baboons soon warmed to the task of searching for breakfast, delicately sifting through the boxes for titbits.
Their larger cousins, the chimpanzees, were the stars of the enrichment programme.
Each chimpanzee demolished its box, flinging paper on to each other to devour the treasures they found.
When satisfied, each retired while exploring its empty box in case something was missed.
Madagascar Lemurs, which were naturally inquisitive, also benefited from the enrichment programme.
"We have to keep thinking of novel ways to keep the primates entertained - a challenge in itself," Ingle said. The primates also used tyre swings, scratch patches and puzzle feeders to stimulate natural behavioural patterns.
Xerox donates the shredded paper to the zoo.