Lisa O’Bryan is in Gombe National Park in Tanzania, where Jane Goodall began the first studies of chimps in the wild. Lisa will be heading into the forests to try to better understand the calls chimps make, to help discover just where the line is (or isn’t) between sounds and speech.
Mpapa (Vitex fischeri) season has begun at Gombe, and this means good news for both the chimps and my research. Mpapa is a species of tree with palmate (hand-like) leaves and small, round fruits that turn purplish-black when ripe. In previous weeks, no one food patch has been capable of satisfying the chimps for a substantial amount of time, so they (and I) have been traveling far and wide. However, with the arrival of mpapa, their pace is mercifully going to slow. A typical mpapa tree can hold at least 5 chimps, and they often grow in groves of multiple trees. That means that a single party of chimps may feed for an hour or more in one small area, not to mention rest and socialize afterwards on their full stomachs.
Not only does this offer a nice break from traveling, but also a clear view of chimpanzee food-associated calling behavior. These trees commonly elicit loud bouts of rough-grunts and pant-hoots, as the chimps scramble up the tree and begin to feed, which I can record with my microphone and recorder. Later on I will be able to compare these recordings to determine which factors (e.g. fruit abundance, hunger level, social context) contribute to differences in call production and acoustics. Ultimately, this will offer greater insight into the information other chimps can obtain from these calls and why they are produced in the first place. In the meantime, the chimps and I will be taking it (relatively) easy, reveling in the joy of mpapa season.
Click here to hear a recent bout of food-associated calls recorded as the chimps were arriving at an mpapa tree: