Suspensory behavior and its role in positional activities of Japanese macaques

Suspensory behavior of free-ranging Japanese macaques was classified based on the kinematics and situations, and incidence of the behavior recorded with the continuous focal animal sampling method was compared between different age groups. Of all age groups, infants used the various types of suspension most frequently, and the frequency declined rapidly with age. Suspension was used as 1) a safety device by infants, to prevent falling down from supports when losing balance, 2) a feeding posture and 3) a supplement for shortage of the reaching length composed of limbs and trunk lengths in young macaques. The roles of suspensory behavior in the development of positional activities in Japanese macaques are briefly discussed.