RESEARCH ARTICLE The Role of Anthropic, Ecological, and Social Factors in Sleeping Site Choice by Long‐Tailed Macaques (Macaca fascicularis) FANY BROTCORNE 1,2 *, CINDY MASLAROV 1 , I. NENGAH WANDIA 3 , AGUSTIN FUENTES 4 , ROSELINE C. BEUDELS‐JAMAR 2 , AND MARIE‐CLAUDE HUYNEN 1 1 Primatology Research Group, Behavioural Biology Unit, University of Liège, Liège, Belgium 2 Conservation Biology Unit, Education and Nature, Royal Belgian Institute of Natural Sciences, Brussels, Belgium 3 Primate Research Center, Universitas Udayana, Bali, Indonesia 4 Department of Anthropology, University of Notre Dame, Notre Dame, Indiana When choosing their sleeping sites, primates make adaptive trade‐offs between various biotic and abiotic constraints. In human‐modiﬁed environments, anthropic factors may play a role. We assessed the inﬂuence of ecological (predation), social (intergroup competition), and anthropic (proximity to human settlements) factors in sleeping site choice by long‐tailed macaques (Macaca fascicularis) occupying a habitat at the interface of natural forests and human‐modiﬁed zones in Bali Barat National Park, Indonesia. Over the course of 56 nights, we collected data relating to physical features of sleeping trees, patterns of the use of sleeping sites within the home range, pre‐sleep behavior, diurnal ranging patterns and availability of natural and human food. Overall, the macaques used 17 sleeping sites with 37 sleeping trees. When the monkeys slept in forest zones, they selected sleeping trees that had larger trunks but were not signiﬁcantly taller than surrounding trees. Though the macaques rarely re‐used sleeping sites on consecutive nights, they frequently re‐used four sites over the study period. The group favored sleeping within the core area of its home range, despite the occurrence of frequent agonistic intergroup encounters there. Macaques preferentially selected sleeping trees located within or near human‐modiﬁed zones, especially when human food was abundant and natural food was scarce. These results partially support the hypothesis that long‐tailed macaques choose their sleeping sites to avoid predation; proximity to human settlements appears to be the primary factor inﬂuencing sleeping site choice in this primate species. Our results reﬂect the strong inﬂuence that anthropic factors have on primates, which subsist in increasingly human‐dominated landscapes. Am. J. Primatol. 76:1140–1150, 2014. © 2014 Wiley Periodicals, Inc. Key words: sleeping site; human proximity; human food; predation avoidance; Bali Barat National Park INTRODUCTION The choice of sleeping sites by diurnal primates reﬂects diverse factors and constraints that are mutually non‐exclusive and highly dependent on context and the species in question. Predation pressure, proximity of food, competition with con- speciﬁcs and physical comfort may inﬂuence the choice of sleeping sites and sleeping trees by primates [Anderson, 1998, 2000]. The predation avoidance hypothesis asserts that primates have evolved anti‐predator strategies at sleeping sites. To minimize detection by a predator, they should select tall emergent trees [Bernard et al., 2011; Fan & Jiang, 2008; Reichard, 1998] and behave in a cryptic manner (e.g. moving silently and rapidly) when entering sleeping trees [Heymann, 1995; Liu & Zhao, 2004; Smith et al., 2007]. Some primates may prefer open‐canopy trees located along riverbanks [Fittinghoff & Lindburg, 1980; Matsuda et al., 2008] and connected to adjacent trees [Albert et al., 2011]. These conditions improve their chances of detecting approaching predators and facilitate Contract grant sponsor: Belgian National Fund for Scientific Research; contract grant sponsor: Fondation Belge de la Vocation  Correspondence to: Fany Brotcorne, Primatology Research Group, Behavioral Biology Unit, University of Liège, 22 Quai Van Beneden, Liège 4020, Belgium. E‐mail: fbrotcorne@gmail. com Received 22 November 2013; revised 9 April 2014; revision accepted 10 April 2014 DOI: 10.1002/ajp.22299 Published online 8 May 2014 in Wiley Online Library (wileyonlinelibrary.com). American Journal of Primatology 76:1140–1150 (2014) © 2014 Wiley Periodicals, Inc.