The role of sleeping sites in the predator‐prey dynamics of leopards and olive baboons

Abstract

Predation is widely recognized as an important selective pressure on prey animals such as baboons (Papio spp.), which face high leopard (Panthera pardus) predation risk, particularly at night. Baboons regularly sleep on cliff faces and in trees at night, ostensibly to avoid such predators. Despite retreating to such "refuges," baboons are most often killed by leopards at or near their sleeping sites. Because of the challenges of studying nocturnal behavior and human-averse predators, few systematic data exist to reveal how leopard ranging near baboon sleeping sites influences baboons' selection of sites and behavior at those sites. To investigate leopard-baboon dynamics at sleeping sites we deployed GPS/VHF radio collars on six representatives of four baboon groups and four leopards during a 14-month field study in Kenya. We used locations recorded every 15 min to identify baboons' cliffside and riverine sleeping sites, the frequency and duration of leopard visits to these sites, and baboons' adjustments in site use after leopard visits. Collared leopards visited riverine sites more frequently than cliffside sites, whereas most baboon groups strongly preferred cliffside sites, suggesting that leopard visits were often due to factors other than baboon presence, and that baboons used cliffside sites to reduce their risk of leopard predation. Regardless of type, collared leopards remained near baboon-occupied sleeping sites longer than vacant ones, indicating interest in hunting baboons then. Baboons at riverine sites departed later on mornings after leopard visits. Baboon groups occasionally shared sleeping sites simultaneously, possibly reducing risk through dilution. However, they did not reduce risk by frequently changing sleeping sites, minimizing detection at sleeping sites, or after leopard visits, arriving earlier the next evening or moving to a different site. Future research should explore if baboons readily detect nocturnal leopard presence and if predation-related changes in sleeping site use have cascading ecological effects. K E Y W O R D Santipredator behavior, felids, predation risk, primates, sleeping sites

Anthropogenic influences on primate antipredator behavior and implications for research and conservation

“…Most of the studies (188/222) used direct observation of subjects that were tolerant of human presence (~85%) but the proportion using direct observation declined over time (Figure ). Several recent studies used alternative methods including GPS data from collared primates and/or their predators (Adams & Kitchen, ; Bidner, Matsumoto‐Oda, & Isbell, ; Isbell & Bidner, ; Isbell, Bidner, van Cleave, Matsumoto‐Oda, & Crofoot, ), camera traps (Boyer‐Ontl & Pruetz, ; Farris et al, ; Isbell & Bidner, ), or predator scats for dietary analysis (Dollar, Ganzhorn, & Goodman, ; Irwin et al, ; Jooste, Pitman, van Hoven, & Swanepoel, ; Lenz & dos Reis, ; McGraw, Cooke, & Shultz, ; Shultz & Dunbar, ; Shultz, Noë, McGraw, & Dunbar, ). For example, Isbell et al () were able to identify encounters between GPS‐collared predators and primates without human interference using predator and prey spatial coordinates to determine when and where species interacted.…”

Capture, immobilization, and Global Positioning System collaring of olive baboons (Papio anubis) and vervets (Chlorocebus pygerythrus): Lessons learned and suggested best practices

“…One was killed by a collared leopard (Isbell et al, ) 144 days after her capture (and transient prolapsed rectum), and we were able to retrieve her collar. Her separation from the other collared female for a week before her death and the location of her last sleeping site on a small boulder never used as a sleeping site before suggest she was incapacitated to some degree before she was killed (Bidner et al, ; Isbell et al, ). We were unable to locate the other baboon or the signal from her collar beyond 165 days after she was captured.…”

“…GPS collars have been deployed on many animal species (Tucker et al, ) but they are less commonly used with primates, in part because the typical observational approach of following habituated primates on foot allows animal locations to be estimated in other ways, including with handheld GPS units (e.g., Eckhardt, Polansky, & Boesch, ; Noser & Byrne, ; Santhosh, Kumara, Velankar, & Sinha, ; Schreier & Grove, ). Although locational data obtained with handheld GPS units are likely to be comparable with those obtained by GPS collars worn by animals if the observer follows the animal's path or corrects for the spatial displacement between the handheld unit and the animal (e.g., Noser & Byrne, ), GPS collars do not require observers to be present with the study animals and thus are useful for investigating questions that have been largely out of reach to date because of the limitations of observers, such as nocturnal movements of diurnal primates (Isbell, Bidner, Crofoot, Matsumoto‐Oda, & Farine, ), complex spatial relationships within and among groups (Farine et al, ; Farine, Strandburg‐Peshkin, Couzin, Berger‐Wolf, & Crofoot, ; Markham, Alberts, & Altmann, ; Markham, Guttal, Alberts, & Altmann, ), and spatio–temporal interactions between primates and their predators (Bidner, Matsumoto‐Oda, & Isbell, ; Isbell & Bidner, ; Isbell, Bidner, Van Cleave, Matsumoto‐Oda, & Crofoot, ). Given the value of data obtained from GPS collars, more trapping and GPS collaring of primates will likely occur in the future.…”

Effects of cold weather on the sleeping behavior of Skywalker hoolock gibbons (Hoolock tianxing) in seasonal montane forest

“…Selection of a suitable sleeping site is, therefore, of the utmost importance in terms of energy preservation, but also may influence individual survival rates (Zhang, Li, Watanabe, & Qi, ). Although antipredator behaviors have been documented as the main factor affecting sleeping site choice in many primate species (Anderson, ; Bidner, Matsumoto‐Oda, & Isbell, ; Fan & Jiang, ; Fei, Zhang, Yuan, Zhang, & Fan, ; Reichard, ; Savagian & Fernandez‐Duque, ), thermoregulation has also been proven to influence sleeping behaviors, which is especially true for those species found in cold, seasonal habitats (Li et al, ; Savagian & Fernandez‐Duque, ; Xiang et al, ). First, primates in temperate habitats often enter sleeping sites earlier in the day (e.g., Trachypithecus francoisi ; Zhou, Huang, Li, & Wei, ) or leave the sleeping site much later when temperatures are low (e.g., Rhinopithecus brelichi , Xiang et al, ), thus prolonging the amount of time spent sleeping.…”