Diet and polyspecific associations affect spatial patterns among redtail monkeys (Cercopithecus ascanius)

Abstract

Animals are predicted to be in closer conspecific proximity during feeding on clumped resources, such as fruits in a tropical rain forest, than when feeding on more dispersed resources, such as leaves or insects. Polyspecific associations are also predicted to affect inter-individual distance because the close proximity of more individuals presumably provides increased protection against predators. We examined the effects of food type and polyspecific association on nearest-neighbor distances of redtail monkeys (Cercopithecus ascanius) in the rain forest of Kibale National Park, Uganda. When redtails consumed fruit, they were closer to conspecific nearest neighbors than when they consumed leaves or insects. When any of the other five monkey species were close or intermingled, redtail monkeys were farther from conspecific nearest neighbors than when they were not in polyspecific associations; however, this effect was apparently driven by redtail associations with grey-cheeked mangabeys (Lophocebus albigena). The aggression mangabeys exhibit to aerial predators may explain this observation. Our results imply a complex relationship between food distribution, predation risk, polyspecific association and spatial patterns that can be explored further in multiple taxa.