Estimating individuals' exposure to predation risk in group-living baboons, Papio anubis

Abstract

In environments with multiple predators, the vulnerabilities attached to the spatial positions of group-living prey are not uniform and depend on the hunting styles of the predators. Coursing predators, mainly canids and hyenas, follow their prey over long distances and attack open areas, making individuals at the edge of the group more dangerous than those at the center (marginal predation). In contrast, ambush predators, mainly cats, approach their prey undetected and appear randomly anywhere in the group; therefore, isolated individuals are at a greater risk of predation. However, identifying individuals at high risk of predation requires the simultaneous recording of predator locations and direct observation of predation events, which are both difficult. Therefore, several theoretical methods have been proposed to assess predation risk (predation risk proxies). In a group of wild anubis baboons exposed to predation by leopards, lions, and hyenas, we calculated predation risk proxies using movement data collected from global positioning system (GPS) collars and found that adult males were on the edge of the group with a higher risk of predation (Hypothesis 1). In addition, adult males were more isolated within this group (Hypothesis 2). None of the predation risks differed among the other age-sex classes. The most dominant male was expected to be in the safety center of the group (Hypothesis 3) but was isolated on the periphery, like the other males. Therefore, we discussed why adult males were more peripheral and isolated.