In social animals, areas where the home ranges of neighboring groups overlap are often underused. The Risk Hypothesis posits that the costs of intergroup conflict create a "landscape of fear," discouraging the use of such shared areas. To test this hypothesis, we observed the behavior of white-faced capuchins (Cebus capucinus) in central vs. peripheral areas of their home ranges. If capuchins perceive areas of home range overlap as "risky," we predicted they would change activity budgets, vocalization rates, and foraging behavior in these areas. A spatially explicit behavioral comparison based on nearly 100 h of focal follows revealed that capuchins socialize less in the periphery (vs. the center) of their home range. Time spent resting, foraging, and engaging in vigilance, as well as vocalization rates, varied in consistent ways across all four study groups, but these differences did not reach statistical significance. Fruit trees near range borders (vs. the center) contained more ripe fruit, and groups spent more time in these trees, with more individuals entering to feed and consuming more fruits. However, capuchins did not alter their foraging behavior in potentially risky peripheral areas in a manner consistent with predictions of optimal foraging theory: intake rates at patch departure were not significantly lower and groups depleted trees to a greater extent along the periphery vs. in the center of their range. These results suggest that while peripheral areas are perceived as risky and this "landscape of fear" contributes to behavioral changes, they also provide resources whose value may outweigh the cost of intergroup encounters.

Terrestrial animals feed on fruit dropped by arboreal frugivores in tropical forests around the world, but it remains unknown whether the resulting spatial associations of these animals are coincidental or intentionally maintained. On Barro Colorado Island, Panama, we used a combination of acoustic playback experiments, remote camera monitoring, and GPS tracking to quantify the frequency of such interactions, determine who initiates and maintains spatial associations, and test whether terrestrial animals adopt a strategy of acoustic eavesdropping to locate fruit patches created by foraging primates. Indeed, 90% of fruits collected in fruit fall traps had tooth marks of arboreal frugivores, and terrestrial frugivores visited fruit trees sooner following visits by GPS-collared monkeys. While our play back experiments were insufficient to support the hypothesis that terrestrial frugivores use auditory cues to locate food dropped by arboreal primates, analyses of movement paths of capuchin monkeys (Cebus capucinus), spider monkeys (Ateles geoffroyi), and coatis (Nasua narica) reveal that observed patterns of interspecific attraction are not merely a byproduct of mutual attraction to shared resources. Coatis were significantly more likely to initiate close encounters with arboreal primates than vice versa and maintained these associations by spending significantly longer periods at fruiting trees when collared primates were present. Our results demonstrate that terrestrial frugivores are attracted to arboreal primates, likely because they increase local resource availability.