Play behavioural tactics under space reduction: social challenges in bonobos, Pan paniscus

Abstract

Several studies have suggested that primates vary in their response to spatial reduction, which represents a challenge for captive animals. Under spatial reduction, primates can adopt various strategies to reduce social tension. Such strategies, which are not mutually exclusive, can involve avoidance and coping tactics. Recently, it has been shown that, during short-term crowding, bonobos may use both grooming and nonreproductive sexuality to avoid a potential rise in tension. Because bonobos are extremely playful, and play can be a risky activity, we tested whether play patterns were selectively avoided under space reduction. We collected daily data via focal animal sampling on a group of bonobos housed in the Apenheul Primate Park (Apeldoorn, The Netherlands) over a 12-month period. Among the adults, we found no difference in the contact play levels (play fighting) between the two space conditions (outdoors, 5000 m2, and indoors, 230 m2), whereas indoors, there was a tendency toward an increase in locomotor–rotational play frequency. These findings indicate that bonobos do not adopt an avoidance tactic to reduce the risk involved in space reduction. Nevertheless, dyads showing higher rates of agonistic encounters were less likely to engage in contact play sessions. Even though it is difficult to affirm that space availability significantly induced higher playmate selectivity, we found that play signals significantly increased indoors, thus suggesting the need for a clearer ‘declaration of intentions’ in an unsafe situation.