Smithsonian National Zoological Park l Friends of the National Zoo



Mindy Babitz, University of St. Andrews, Scotland

Tool use by monkeys and apes has held scientific interest in recent years because it was once thought to be a uniquely human activity. Most studies have focused on the toolusing abilities of capuchin monkeys and chimpanzees, two species which have been observed to use tools in the wild. For example, capuchins use branches as weapons to scare away other animals or humans, and chimpanzees use twigs to "fish" for termites and stones to crack open nuts.

In the wild, tool use is particularly helpful for extracting hard-to-reach foods, such as termites hidden inside a mound, insects hidden under tree bark, and the edible parts of fruits or nuts that are protected by hard shells. Capuchins in the wild are also good at finding hidden foods without using tools. For instance, they will peel back bark on trees or dig in the soil with their hands to find insects. Capuchins and chimpanzees are skilled object manipulators in captivity as well and will even combine two or more objects in play. Play with objects might help animals discover how the objects can be used as tools. Those skills could come in handy when confronted with an otherwise inaccessible piece of food.

We know very little about Sulawesi macaques' abilities to use objects as tools. They have not been observed using tools in the wild, and although they may look for insects under leaves, they do not manipulate their environment to find food in the same way that capuchins and chimpanzees do. There is some evidence, however, that in zoos, Sulawesi macaques manipulate objects similarly to tool-using capuchins, Tonkean macaques, and lion-tailed macaques.

Are Sulawesi macaques also capable of using objects as tools? Perhaps in the wild they do not need to use tools because the food they eat is readily accessible, but whether or not they are capable of using tools in captivity remains a question. This idea will be explored in the Think Tank exhibit starting in September of 1998.

We will provide Sulawesi macaques with a variety of objects to play with. The macaques' manipulations of those objects will be observed to see how many different things they can do with them. They will also be provided with objects that can be used as tools to obtain food rewards that are out of reach. For example, branches are ideal for raking in hard-to-reach food, sticks are useful for extracting food from containers, and leaves can soak up liquid for drinking. Our aim is to discover the nature and limitations of the Sulawesi macaques' tool use and to share that knowledge with visitors and the scientific community.