GPS-identified vulnerabilities of savannah-woodland primates to leopard predation and their implications for early hominins

Abstract

Predation is thought to have been a key selection pressure in primate evolution, especially in the savannah-woodland habitats where several early hominin species lived. However, predator-primate prey relationships are still poorly understood because human presence often deters predators, limiting our ability to quantify the impact of predation. Synchronized high-resolution tracking of leopards (Panthera pardus), vervets (Chlorocebus pygerythrus), and olive baboons (Papio anubis) during a 14-month study in Kenya revealed that increased vulnerability to leopard predation was not associated with higher encounter rates, smaller body size, smaller group size, or greater distance from refuges, contrary to long-standing inferences. Instead, the initiation, rate, timing, and duration of encounters, outcome of approaches, and predation events showed only a diel pattern of differential vulnerability. In the absence of human observers, vervets were more vulnerable during the day, whereas baboons were more vulnerable at night, but overall neither species was more vulnerable than the other. As our results show that leopards avoided baboons during the day and hunted them at night, we suggest that the same pattern would have applied to hominins-because they were even larger than baboons and bipedal, resulting in similarly offensive capability on the ground during the day but poorer agility in the trees at night, especially as they became committed bipeds. Drawing from hominid behavior and archaeopaleontological and ethnographic evidence, we hypothesize that ground-sleeping hominins initially dealt with this formidable threat by using stone tools to modify Acacia branches into 'bomas', thorny enclosures that provided nighttime shelter. The ability of hominins to create their own nightly refuges on the ground wherever Acacia spp. were available would have allowed them to range more widely, a crucial step in furthering the spread of hominins across Africa and beyond.

Leopard predation on gelada monkeys at Guassa, Ethiopia

“…Further, in the two instances in which researchers were spotted by a leopard in close pursuit of a gelada, the natural outcomes of these interactions may have been altered. As such, the use of GPS collars on both predators and prey (e.g., Isbell et al, 2018) and other noninvasive data collection methods (camera trapping, fecal surveys, etc.) are promising avenues for supplementing direct observations of predator–prey interactions.…”

“…Among predators known to predate upon primates, large felids are especially important, having been implicated in more primate attacks than any other category of predator, including raptors, canids, hyaenids, small carnivores, and reptiles (Hart, 2007). The most widespread of the large felids (Jacobson et al, 2016), leopards ( Panthera pardus ) are known to prey on a wide range of extant catarrhine primates, including Asian and African colobines, guenons, mangabeys, baboons, great apes, and humans (Busse, 1980; D'Amour, Hohmann, & Fruth, 2006; Isbell, 1990; Isbell, Bidner, Van Cleave, Matsumoto‐Oda, & Crofoot, 2018; Karanth & Sundquist, 1995; Koziarski, Kissui, & Kiffner, 2016; Matsumoto‐Oda, Isbell, & Bidner, 2018; Naha, Sathyakumar, & Rawat, 2018; Tutin & Benirschke, 1991; Zuberbühler & Jenny, 2002). There is also evidence from the fossil record suggesting that leopards preyed on now‐extinct hominins (e.g., Paranthropus robustus : Brain, 1970; Homo neanderthalensis : Camarós, Cueto, Lorenzo, Villaverde, & Rivals, 2016).…”

“…There is also evidence from the fossil record suggesting that leopards preyed on now‐extinct hominins (e.g., Paranthropus robustus : Brain, 1970; Homo neanderthalensis : Camarós, Cueto, Lorenzo, Villaverde, & Rivals, 2016). Thus, leopard predation has probably long played a role in shaping the predator defense and avoidance adaptations of many primate species, including members of the hominin lineage (Isbell et al, 2018; Zuberbühler & Jenny, 2002).…”

“…Although a number of studies have investigated leopard predation on primates inhabiting lowland rainforests or savannahwoodland habitats (e.g., Boesch, 1991;Isbell, 1990;Isbell et al, 2018;Zuberbühler & Jenny, 2002), little is known about primateleopard interactions in more open environments where refugia from predators are scarce. This gap in our knowledge is due to both the rarity of observed predation events in the wild in general (Isbell, 1994a;Miller & Treves, 2011) Living at elevations of 1,700-4,600 m above sea level (a.s.l), geladas are medium-sized and sexually dimorphic monkeys that form multilevel societies (Bergman & Beehner, 2013).…”

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

“…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. Camera traps also allowed researchers to collect behavioral data without direct observation (Boyer‐Ontl & Pruetz, ; Farris et al, ).…”