Do guenons usually use tools at the Zoo?
Stromberg: Think Tank—the exhibit where the guenons live—focuses on three main themes: language, society and tool use. Our Allen’s swamp monkeys and Schmidt’s red-tailed monkeys have never shown keepers that they understand the concept of using a tool to get a reward. Involving them in this study, though, could help us learn more about their understanding of tool use.
Some of the enrichment items the monkeys receive require some aspect of problem-solving in order to obtain a reward. The information we learn from this study could shape the types of enrichment we provide them in the future.
All of the research projects that we do with our primates use operant conditioning. That means that the animals’ participation in the study is voluntary and, at any point, they have the choice and opportunity to walk away. If they do elect to participate, then they receive a reward, typically in the form of food. Most of our primates that qualify for these studies eagerly participate—especially when peanuts are offered as a reward!
How did the guenons react to the tools?
Stromberg: As with all primate cognitive studies, the individual personalities of each guenon really shines through.
Before one of our female Schmidt’s red-tailed monkeys, Chi Chi, moved to another Zoo, she participated in this study in the summer and fall of 2018. She seemed to enjoy the test but did not like the sound that the tools made when they came into contact with the exhibit mesh. We added a towel “bumper” to soften the sound.
Our male Allen’s swamp monkey, Nub Armstrong, will do just about anything for a peanut. He often gets very impatient and will push on the box that hides the tools in between trials, desperate to make the peanuts appear sooner!
Did their knack for using tools surprise you?
Painter: Considering that this is the guenons’ first cognitive study at the Zoo, they took to the task pretty quickly. The number of initial training sessions they needed in order to consistently choose the correct tool was within the same range as that of a group of capuchin monkeys at Bucknell University that have participated in cognitive tasks for years!
Stromberg: I was very impressed that each of the guenons eagerly separated from their group to participate in the study, even though the tools were foreign to them, both in material and color. They demonstrated a strong desire to participate and didn’t hesitate to sit in front of and interact with these strange-looking tools!