When pigtailed macaques cannot select for optimal sleeping sites in degraded habitat

Primates spend half of their lives in sleeping sites and should select them carefully to maximize fitness. Sleeping site selection in degraded habitat, with reduced availability and quality of resources, is therefore likely to play a leading role in primates’ survival. We aimed to assess the impact of habitat degradation on sleeping site selection patterns in a troop of northern pigtailed macaques, using 3 non-mutually exclusive hypotheses: null hypothesis of random selection, predation avoidance, and food proximity. We identified 107 sleeping sites with only 15 reused sites selected at random in the Sakaerat Biosphere Reserve, northeastern Thailand. After analyzing forest structure at sleeping sites and random sites, we found a general low availability of large and tall trees. Our results show that macaques did not select sleeping sites at random; probability of site selection increased in familiar areas with a high number of stems and with emergent trees. Following the predator avoidance hypothesis, these characteristics are likely to facilitate macaques escape in case of predator attack and also to decrease predator detection at their sleeping sites. Additionally, the food proximity hypothesis seems to be the leading strategy in explaining sleeping sites selection of this degraded habitat. Macaques multiplied their sleeping sites following food distribution, and slept inside or in close proximity to their feeding area, which is likely to maximize their energy intake. Our results highlight the impact habitat degradation may have on sleeping site selection in a flexible species.