Early organization of activity states was studied in 17 tufted capuchin (Cebus upella) infants from birth to 11 weeks of age. Development of exploration and interactions with mothers and other group members were studied in 14 of these infants up to the age of 1 year. Activity profiles changed from 3 to 8 weeks as infants began to move off mothers and explore their environments. From 2 to 6 months time with mothers decreased; time alone increased correspondingly. Time spent with other group members did not vary significantly over the first year. By 7-9 months capuchin infants spent more time alone or with other group members than with mothers, although weaning was still not completed by the end of the first year. Simple environmental exploration began in the 2nd month and reached stable levels by 4 months. Complex manipulation of food and objects first began at 3-4 months and increased to stable levels in the second half of the first year. Some preliminary differences were evident between infants living in indoor cages and those living in indoor/ outdoor runs. Infants in cages spent less time in dorsal contact with mothers, and less time in social play and proximity to other animals than those in runs. Instead, infants in cages spent more time alone and engaged in more manipulation of food. Some measures of social and exploratory behavior showed a high degree of variability which may be usefal in exploring individual differences in infant temperament or reactivity. 0 1995 Wiley-Liss, Inc.*

The effects of adding woodchip litter to bare-floored pens, burying monkey chow in the woodchips, and scattering sunflower seeds in woodchips was studied in 2 stable social groups of rhesus macaques (Macaca mulatta) to ascertain the effects of these manipulations on levels of foraging, exploration, abnormal behavior, social interactions, and urinary cortisol levels. The addition of woodchips increased exploration and feeding levels and decreased social interactions. Burial of regular monkey chow in woodchips had little effect on behavior beyond that of the woodchips alone, increasing exploration and decreasing passivity. The addition of sunflower seeds to the woodchips encouraged increased feeding and exploration and led to decreases in passivity and social interaction. There was little discernible effect of woodchip enrichment on urinary cortisol values. In contrast to some previous studies, there was no effect of wood &ips or sunflower seeds on the occurrence of agonistic interactions, play, or abnormal behavior patterns.

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