Sleeping in good company: strategies for using sleeping places among Guinea baboons

A recent study by the German Primate Center (DPZ) – Leibniz Institute for Primate Research provides insights into the sleeping habits of Guinea baboons (Papio papio) in Senegal, West Africa. The study shows that these primates apparently choose their sleeping sites regardless of whether predators are present in the area or whether there is an increased risk of infection with parasites. Unlike other baboon populations, the baboons observed appear to compete little for suitable sleeping sites, preferring instead to sleep in close proximity to familiar neighboring groups (Ecology and Evolution).

Guinea baboons live in large groups that divide into smaller subgroups that use overlapping territories. Over a period of four years, researchers studied the sleeping habits of guinea baboons in Niokolo-Koba National Park in Senegal using GPS collars. This allowed them to track which sleeping sites the animals used, how often they changed them, and whether external influences, such as predators like leopards or proximity to other groups, affected their behavior. The study is part of long-term research in Simenti, which has been investigating the behavior, cognition, and ecology of Guinea baboons since 2007 in order to better understand the selection factors that influence the social organization of primates. As expected, the baboons slept mainly in the tall trees of the gallery forests along the Gambia River, which offer potential protection from predators due to their smooth bark, partly thorny trunks, and close connection to neighboring trees. Many sleeping trees were used repeatedly over a long period of time. Although it is assumed that frequently changing sleeping places can reduce the risk of being discovered by predators or exposed to parasites due to accumulated excrement, the baboon groups studied probably changed their sleeping places depending on the situation and not specifically to avoid risk. The availability of food in the foraging area or competition between groups also had little influence on the choice of nighttime location.

The analysis revealed that baboon groups spent the night in close proximity to each other even when there were sufficient alternative options available. The average distance between the sleeping trees of the two closest neighboring groups was less than 50 meters. In addition, groups usually slept next to the groups with which they preferred to roam during the day.

Although sleeping in larger groups can help protect against predators, the usage patterns of individual groups suggest less of a deliberate risk avoidance strategy and more of a stronger emphasis on social preference in the choice of sleeping sites.

The analysis suggests that guinea baboons do not choose their sleeping places based on targeted risk avoidance, but rather on a situational basis, with existing social ties to neighboring groups being a key influencing factor. It is still unclear how they react to nighttime disturbances caused by thunderstorms, predators, or other external influences, and whether such experiences influence their decisions the following day. Further studies using complementary methods, such as autonomous audio recorders and camera traps, could provide new insights in this area.

Ohrndorf L, Mundry R, Beckmann J, Fischer J, Zinner D (2025): Spatiotemporal patterns of sleeping site use of Guinea baboon parties (Papio papio). Ecology and Evolution15 (7): e71610. https://doi.org/10.1002/ece3.71610