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.

Primates are prolific dispersers of seeds via endozoochory (i.e., defecation and spitting). In contrast, epizoochorous seed dispersal (i.e., via adhesion to fur) has rarely been observed in primates. On the Guassa Plateau in north-central Ethiopia, grasseating geladas (Theropithecus gelada) regularly carry on their fur the barbed seeds of a commonly eaten plant, a low-lying herbaceous forb called Agrocharis melanantha [Apiaceae]. Here, we describe the basic ecology of this plant-primate relationship.For 24 months (November 2017-December 2019), we monitored the number and location of A. melanantha seeds on the fur of geladas (n = 225 individuals) from four age-sex classes: adult males, adult females, juveniles, and infants. Seed accumulation (n = 12649 seeds in total) was seasonal and closely tracked patterns of landscape vegetation phenology, peaking in September near the end of the rainy season. During seasonal periods of heavy seed accumulation, larger animals carried more seeds, which accumulated most often on the hindlimbs and on the long-haired "cape" (a secondary sexual characteristic) of adult males. Geladas almost never removed seeds during self-or social grooming. Rather, data on seed gain and loss from focal follows indicate that geladas gain and lose seeds every few minutes as they walk and sit in an upright feeding position amidst terrestrial vegetation. We estimate that, on average, geladas disperse seeds roughly 80 m from their parent plants. Geladas appear to exert negative and positive fitness impacts on A. melanantha by regularly consuming its herbaceous and underground tissues and dispersing its seeds.