Interaction with objects by group-living Saimiri sciureus

We have studied the spontaneous interaction with small, inedible objects by group-living Saimiri. Twenty-one animals living in a large outdoor enclosure were presented with a set of 10 novel objects of diverse materials, colors, sizes, and shapes. We have used a sampling technique to record the number of monkeys interacting with each object; qualitative observations complemented these measurements. Next day the same objects were presented again and the observations continued. This experiment was repeated with some variations three times over a period of six months. The highest score for novel objects was obtained immediately upon objects presentation; afterwards the score sharply decreased for that day. On second presentation of the same objects the scores were more evenly distributed during the day, the cumulative total resembling that of day one. Objects' characteristics influenced the amount of interaction with them. The important factors seemed to be the material the objects were made of and their complexity. The objects that were contacted most frequently elicited intense investigative behavior and social play. These results differ from some previous works in which Saimiri were observed to interact only rarely with novel objects.