May 9, 2013 — For the past four years our research team has investigated lemur cognitive abilities. Adapted to unique niches in Madagascar, lemur species differ considerably in sociality, foraging patterns, and other characteristics that may have caused them to evolve different problem-solving skills. We test these skills through interactive experiments, that may require lemurs to use social cues to acquire food, or to resist the desire to search for food in a location where it was once was, but is no longer (something that might be important for an animal who eats fruit that ripens and then rots). When lemurs participate in these studies, we bring them into a room within their own enclosure, and close the doors on both sides so that their group mates cannot enter and also figure out ways to get the treats. While these doors were closed, we made some interesting observations about lemur social interactions.

When a ring-tailed lemur gets lost in the wild, she opens her mouth into a round shape, as though she is about to whistle, and lets out a “Miaouuuu!” sound like a cat’s. This vocalization, called a contact call, is thought to maintain group cohesion among ring-tailed lemurs in the wild. Ring-tailed lemurs at the Duke Lemur Center often made this sound while they worked in rooms with us. We noticed that when certain lemurs made a contact call, many group members responded –the building wing was filled with a chorus of meows. For other lemurs, however, the group was silent, even if they called many times.

Studies have shown that contact calls are individually distinct when you look at them on a sonogram, a display that shows the frequency of sounds over time –every lemur has her own voice. We hope to understand the social bonds that underlie these responses. Do lemurs have “friends” that they respond to more than others? Currently, we are still in the process of recording vocalizations for future experiments. We follow the lemurs around for several hours most days of the week, standing below trees when they climb up high in the forest, or in an inside hallway when they play inside. Sometimes they are silent, just sleeping, and other times, everyone starts to vocalize at once!

Rachna Reddy
Lab Manager
Hare Research Group
Duke University