Abstract
Stone handling behaviour (SHB) has been observed among the free-ranging Arashiyama E troop of Japanese macaques (Macaca fuscata) in Kyoto, Japan, since 1979. For identifying the proximate factors of SHB, I analyse (1) the occurrence of SHB and the time change in the rate of stone-handlers, (2) the correlation of SHB with artificial feeding and stone-handlers' emotional states, and (3) the differences in post-provisioning behaviours between stone-handlers and non-stone-handlers.
Most SHB tended to occur after artificial feeding. The rate of stone-handlers in the troop increased rapidly, and reached a peak in 4 to 5 minutes after provisioning. Stone-handlers tended to be lower in dominance rank. During the post-provisioning period, they tended to (1) feed on less artificial food, but more natural food, (2) have less aggressive interactions, and (3) do more frequent self-scratching, than non-stone-handlers. These results indicate that stone-handlers are under a conflict situation between an unsatisfied feeding drive and an avoidance drive from aggressive interaction. This emotional conflict between feeding and aggression-avoidance drives is likely to be the main proximate factor of SHB.
