Abstract:
The study of animal play is highly complex since its potential functions vary with social and environ-
mental circumstances. Although play is generally characteristic of immature animals, it may persist in
adults in its social form, particularly when interacting with young individuals, and less often with other
adult playmates. We measured the amount of social play in 62 wild adult howler monkeys, Alouatta
palliata, belonging to seven different groups in Mexico and Costa Rica. Overall, adult play represented a
small mean proportion of observation time across all groups, but it was present in all study groups.
Generalized linear mixed models revealed that group size correlated with both adulteadult and adult
eimmature play, supporting the hypothesis that more individuals provide more play opportunities.
While play between adults decreased with increases in the immature to adult ratio, we did not nd a
clear preference for adults to play with immatures, emphasizing the importance of playing with other
adult peers. Conversely, adults played more with immatures as the immature to adult ratio increased,
which may correspond with the role adulteimmature play may have in the socialization process of
young individuals. More time dedicated to foraging on fruits corresponded with more adulteadult play.
This nding, aside from being associated with more energy being available to engage in play, supports
the hypothesis that play is a mechanism for solving con icts associated with contest competition by
either reducing social tension and/or ghting for a limited resource. The range of factors affecting social
play indicates that this behaviour in adult howler monkeys is facultative, having af liative, socializing
and competitive roles, depending on the socioecological context.
