Location effects of social partner on experimental foraging in the squirrel monkey

The effect of social context on experimental foraging in squirrel monkeys (Saimiri sciureus) was investigated. The 12 subjects comprised six pairs in which strong social preference and attraction had been demonstrated during observations of a stable group. Individuals were first trained to discriminate spatially separated rich and poor foraging bins containing 75% and 25% of the food items, respectively, with their partners restrained equidistant from the two bins. The monkeys invested an average of 75.5% of their foraging time in the rich bin. Each individual was then tested with its partner restrained in different locations relative to the bins to determine the effect of partner proximity on foraging patterns. Foraging efficiency at the start of a session was enhanced when the partner was restrained adjacent to the rich bin compared to restraint away from this bin. Over an entire foraging session, however, all conditions providing partner accessibility were similar in yielding enhanced foraging efficiency compared to partner absence. Little time was spent in close physical proximity to the partner under any condition. It is suggested that accessibility of the social partner, rather than close physical proximity, has an important influence on the foraging squirrel monkey. © 1995 Wiley-Liss, Inc.