How do wild baboons (Papio ursinus) plan their routes? Travel among multiple high-quality food sources with inter-group competition

Abstract

How do humans and animals travel between multiple destinations on a given foraging trip? This question is of theoretical and practical interest, yet few empirical data exist to date. We examined how a group of wild chacma baboons travelled among multiple, simultaneously fruiting mountain fig trees (Ficus glumosa). In the course of a 16-month study, this highly preferred fruit was available during a 3-week period, from relatively few sites, which were also utilized by four larger baboon groups. We used directness of route and travel speed of 13 days of observation, and approach rates of 31 days of observation to differentiate between purposeful and opportunistic encounters with 50 fig trees. The study group visited a total of 30 fig trees overall, but only 8 trees per day on average. Each morning, they travelled along a highly repetitive route on all days of observation, thereby visiting 2–4 fig trees. They approached these trees rapidly along highly directed paths without intermittently exploiting other food sources that were available in large quantities. Then, they abruptly changed behaviour, switching to lower travel speed and less directed routes as they foraged on a variety of foods. They approached additional fig trees later in the day, but approach rates were similar to those at times of year when fruit of this fig species was unavailable; this suggested that encounters with trees after the behavioural switch were not planned. Comparing visits to purposefully and opportunistically encountered trees, we found no difference in the average time spent feeding or frequency of feeding supplants, suggesting that purposefully and opportunistically visited trees had similar values. We conclude that when foraging for mountain fig fruit the baboons’ cognitive maps either contain information on relatively few trees or of only a single route along which several trees are situated, leading to very limited planning abilities.