干旱区生态环境知识资源中心

Patterns of alarm calling and their implications for perceived predation risk were explored among adult baboons Papio cynocephalus ursinus in four social groups differing in both size and composition (22-55 members with one to six adult males) in a desert population. Data were collected in a held experiment where alarm calls were elicited from baboons under similar conditions of risk in response to the approach of a potential predator, a human observer. The results show that females call more frequently than males in most groups. In addition, the median calling rate of females shows an exponential increase in smaller groups. These patterns suggest that females in small groups may perceive the highest risk in this population. Nevertheless, there was no clear tendency for either sex to be the first to call. The observer approaches were also used to evaluate the influence of group size on the ease of detection of 1. the baboons by the observer; and 2. the observer by the baboons. Group size did not appear to affect detection distances for either subject, although the probability that baboons were more likely to perform alarm calls before the observer had detected them increased in smaller groups.