Leopard predation on gelada monkeys at Guassa, Ethiopia

Abstract

Predation is widely believed to exert strong selective pressure on primate behavior and ecology but is difficult to study and rarely observed. In this study, we describe seven encounters between lone wild leopards (Panthera pardus) and herds of geladas (Theropithecus gelada) over a 6‐year period in an intact Afroalpine grassland ecosystem at the Guassa Community Conservation Area, Ethiopia. Three encounters consisted of attempted predation on geladas by leopards, one of which was successful. All three attacks occurred in low‐visibility microhabitats (dominated by tussock graminoids, mima mounds, or tall shrubs) that provided leopards with hidden viewsheds from which to ambush geladas. An additional four encounters did not result in an attempted attack but still document the consistently fearful responses of geladas to leopards. In encounters with leopards, geladas typically gave alarm calls (n = 7 of 7 encounters), reduced interindividual distances (n = 5), and collectively fled towards or remained at their sleeping cliffs (n = 7), the only significant refugia in the open‐country habitat at Guassa. Geladas did not engage in mobbing behavior towards leopards. Encounters with leopards tended to occur on days when gelada herd sizes were small, raising the possibility that leopards, as ambush hunters, might stalk geladas on days when fewer eyes and ears make them less likely to be detected. We compare the behavioral responses of geladas to leopards at Guassa with those previously reported at Arsi and the Simien Mountains and discuss how gelada vulnerability and responses to leopards compare with those of other primate species living in habitats containing more refugia. Lastly, we briefly consider how living in multilevel societies may represent an adaptive response by geladas and other open‐country primates to predation pressure from leopards and other large carnivores.

Ecological and social pressures interfere with homeostatic sleep regulation in the wild

“…Notably, however, we did not find that baboons decreased their investment in sleep on the night of leopard attack. This surprising result may reflect leopards' disinclination, as stealth hunters, to launch repeated attacks (Hayward et al, 2006;Lin et al, 2020), or indicate that baboons perceive uncertainty in the level of risk as potentially more dangerous than a confirmed threat.…”

Ecological and social pressures interfere with homeostatic sleep regulation in the wild

“…Notably, however, we did not find that baboons decreased their investment in sleep on the night of the leopard attack. This surprising result may reflect leopards’ disinclination, as stealth hunters, to launch repeated attacks ( Hayward et al, 2006 ; Lin et al, 2020 ), or indicate that baboons perceive uncertainty in the level of risk as potentially more dangerous than a confirmed threat. It is also possible that baboons did, in fact, sleep less following the attack, but remained exceptionally still, in a state of highly elevated vigilance.…”

Carbon and strontium isotope ratios shed new light on the paleobiology and collapse of Theropithecus, a primate experiment in graminivory

“…Third, reduced grooming is expected to destabilize group cohesion (Dunbar, 1993) and increase predation risk (Lin et al, 2020), including at the hands of early Homo (Shipman et al, 1981).…”