Although all animals sleep, remarkably little is understood about it. Most research on sleep is conducted in sleep laboratories, disconnected from its natural context. The Mpala Baboon Research Project provides an exciting opportunity to study sleep in a real setting, offering insights into collective sleep behavior and how this shapes complex social systems. Sleep is an inherently risky behavioral state, defined by decreased sensitivity to environmental stimuli. Sleeping together with other individuals offers various advantages, including protection from predators and buffering against cold nighttime temperatures. However, group members also compete with each other over access to the safest, warmest, most comfortable sleeping spots, or the chance to sleep next to their preferred co-sleeping partners. Decisions about where to sleep are important, but assessing the options is complicated: the availability and quality of each position within the sleep site depends on the choices made by other group members.
To understand how group-living animals make complex, socially-contingent decisions, thermal tracking and accelerometry are used to investigate how wild olive baboons incorporate environmental and social factors into their choices about where to sleep, and how these decisions impact the quality of their sleep. The focus is on how these primates incorporate factors such as predation risk, temperature, and social relationships into their sleep site selection. As the night starts to fall, baboons arrive at their sleep sites and begin selecting their spots. They consider various physical features such as branch stability, protection from wind and rain, and predator accessibility. Using 3D laser scans, these sites are reconstructed to measure their quality. At night, thermal cameras track baboons’ movements, helping researchers understand their decision-making process. Baboons are especially vulnerable to nocturnal predators such as leopards. To mitigate this risk, they choose to sleep in trees or on cliffs, selecting perches that are difficult for predators to reach. However, predation risk is just one of many considerations. The research aims to reveal how baboons balance these multifaceted decisions influenced by their group dynamics. Social factors are equally critical in these decisions. Baboons prefer to sleep near family or social partners and must navigate the dominance hierarchy to secure their spots.
The expectation is that the social environment maps onto the physical environment, creating a constantly evolving decision-making landscape that updates every time members of the group make a decision or change their mind. The goal is to understand how individuals navigate this complicated collective decision-making process, and disentangle how individual characteristics, social relationships, and decision-making dynamics interact to affect where baboons sleep. Further, the quality of their decisions is assessed by monitoring individual sleep quality – an important determinant of health in primates.
This research provides a window into the mechanisms and consequences of collective decision-making in social animals. By understanding baboons’ sleep choices, broader insights are gained into how animals navigate complex environments and social structures, enhancing our knowledge of animal behavior and ecology.
Sponsoring organization/institution: Max Planck Institute of Animal Behavior, University of Konstanz
Duporge, I., Kholiavchenko, M., Harel, R., Rubenstein, D., Crofoot, M., Berger-Wolf, T., Lee, S., Wolf, S., Barreau, J., Kline, J. and Ramirez, M., 2024. BaboonLand Dataset: Tracking Primates in the Wild and Automating Behaviour Recognition from Drone Videos. arXiv preprint arXiv:2405.17698.
Loftus, J.C., Harel, R., Núñez, C.L. and Crofoot, M.C., 2022. Ecological and social pressures interfere with homeostatic sleep regulation in the wild. Elife, 11, p.e73695.
Harel, R., Loftus, J.C. and Crofoot, M.C., 2021. Locomotor compromises maintain group cohesion in baboon troops on the move. Proceedings of the Royal Society B, 288(1955), p.20210839.