The Travelling Salesbaboon: Chacma Baboon Route Efficiency in Multi-Stop Daily Travel Routes

The ability to navigate through both familiar and unfamiliar environments is of critical importance for foraging efficiency, safety, and energy budgeting in wild animals. For animals that remain in the same home range annually, such as grey-footed chacma baboons (Papio ursinus griseipes), movement efficiency is expected to reflect familiarity with the home range as well as the nature of the resources within it. For example, resources that are patchy, transient, or seasonal present a greater spatial cognitive challenge, and travel between them may be less efficient than for more widespread or permanent resources. Here, we analyse daily route efficiency in adult female grey-footed chacma baboons at Gorongosa National Park, Mozambique. We use GPS data taken at 15 min intervals from collars deployed on two baboons in each of two study troops (four total) to identify areas of interest used during daily ranging periods (sleep site to sleep site). We then compare the length of the route taken between a given day’s patches to routes calculated by two alternate optimisation heuristics as follows: the nearest neighbour method, in which the subject repeatedly travels to the next most proximate patch and does not necessarily return to the same place, and the Concorde algorithm, which calculates the shortest possible route connecting the day’s patches. We show that baboons travel more efficient routes than those yielded by the nearest-neighbour heuristic but less efficient routes than the Concorde method, implying some degree of route planning. We discuss our novel method of area of interest identification using only remote GPS data, as well as the implications of our findings for primate movement and cognition.