Martie interacting with a monkey

Featured student project: Martie Stothoff

For her senior project Martie studied the behavioural response in captive common marmosets (Callithrix jacchus – the second smallest primate in the world) to the introduction of a novel foraging-enrichment device. In captivity, animals often become bored, depressed, or stressed, and enrichment is a way in which caretakers can improve the lives of captive animals. Compared to many other animals, monkeys are very smart, and therefore need even more stimulation to keep them physically and psychologically active. Knowing how to keep animals happy and healthy in captivity is a highly important aspect of conservation biology.

In the wild, marmosets don’t just collect fruits and insects like many other monkeys do, but gouge trees with their teeth and suck out the sap. In captivity however, most monkeys are fed fruits and vegetables from stationary bowls, which provides enough nutrition, but gives no practice in natural ways foraging, and makes the marmosets lose their ability to gouge trees. With the help of Bard professor Felicia Keesing, Martie designed a novel enrichment device for captive marmosets living in captivity in Costa Rica. The device was made of a small wooden log with holes drilled all around it, that Martie filled with honey and hang up vertically in the cages. This study was the first ever to try honey as a sap substitute for common marmosets, and Marite found that this simple device increased positive foraging behaviours and decreased inactivity, significantly improving the well-being of captive monkeys.