Gombe 2013: The Case of the Missing Chimps

A foot and knuckle print left in the sand by a chimp recently traveling along the shore of Lake Tanganyika

Lisa O’Bryan is in Gombe National Park in Tanzania, where Jane Goodall began the first studies of chimps in the wild. Lisa is in the forest to try to better understand the calls chimps make, to help discover just where the line is (or isn’t) between sounds and speech.

Recently, the chimps pulled a trick out of their sleeve that they often perform this time of year: they disappeared. Well, not literally, but they could just as well be vacationing in Zanzibar right now and I would be none the wiser.

The chimps were already fairly spread out across the park feeding in diffuse fields of budyenkende. Then, with the small orange fruits beginning to dwindle and no other species of fruit ready to take its place, they took their solitude to the next level. To avoid competition for what little high-quality food is available, each chimp retreated to its own corner of the park to go it alone.

Every once in awhile we spend a day in the forest without finding a suitable chimp to follow (e.g. an adult male we haven’t followed in the past week). However, in the past two weeks our failure rate has quadrupled. Often, we spend hours in the forest and don’t see or hear ANY chimps at all.

Dung beetles quickly roll away fresh droppings by a chimp moving through the area
Dung beetles quickly roll away fresh droppings by a chimp moving through the area

Usually, we are able to go to vantage points to listen for the loud pant-hoot vocalizations chimps use to communicate long distances, but now, the forest is strangely quiet. Plus, since there are no reliable feeding areas to check in on, we don’t have much information to go on. So, we spend our days wandering through the forest looking for dark shapes in the vines and listening for the subtle sounds of shifting vegetation.

However, occasionally we get clues which can help us in our search. Fresh droppings, footprints, and discarded foods are all signs that a chimp was recently in the area. While reassuring that there are still chimps in the park, we are then faced with the challenge of figuring out in which direction and how far they may have gone. This is when footprints come in handy!

While we knew this time of year was coming, it is always amazing how easily these charismatic, boisterous animals disappear into the undergrowth. With only a few more weeks left in the field, it looks like the chimps are going to make us work extra hard for these last bits of data!


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Meet the Author
Lisa O’Bryan is a PhD candidate in the Department of Ecology, Evolution and Behavior at the University of Minnesota. Her dissertation research focuses on the function of chimpanzee food-associated calling behavior. She is currently conducting fieldwork at Gombe National Park through the end of May 2013.