The ontogeny of foraging in squirrel monkeys, Saimiri oerstedi

Abstract

The development of foraging and locomotor independence by wild infant squirrel monkey is described. Infants began to locomote independently during the fourth week of life and successful foraging appeared within the next 2 weeks. Infants were weaned by 16 weeks. The frequency and targets of foraging activities in infants became indistinguishable from those of older animals within 4·5 months after the onset of foraging, with four exceptions. Compared with older animals, infants exhibited (1) greater reliance on methods that did not involve prehension of small prey, (2) less visual inspection of potential foraging sites, (3) less skilled processing of certain prey to remove potentially toxic gut contents and to prevent escape, and (4) less avoidance of urticaceous caterpillars. Observations of infants watching other infants experiencing difficulties with noxious prey and prevention of approach to noxious prey by adults suggest that avoidance of certain species could be transmitted socially. Otherwise, no direct social influence on foraging was shown. Only a few features of foraging require extensive individually acquired motor skills, and weanlings can feed themselves adequately before these skills are developed. Infants in the wild population were weaned much earlier than has been observed in captive groups, and at about the age at which abilities are sufficiently mature for foraging to reach minimal efficiency. The age of weaning in this population probably represents the lower limit for this taxon.