Sex differences in the foraging behavior of squirrel monkeys in a seasonal habitat

Summary

The effects of sex and seasonal changes in food abundance on foraging behavior was studied in squirrel monkeys (Saimiri oerstedi) in Costa Rica over an eleven-month period. Females searched for and ate food at significantly greater frequencies than did males throughout the study. The frequency of the specific foraging techniques used occasionally differed significantly within seasons, but not across the study period. Few differences were found in the foraging behaviors of nonreproductive sexually mature females compared to females that were pregnant or lactating. The major exception was that during the month following parturition reproductive females foraged for flowers and fruits more frequently than did non-reproductive females. The reduction of time spent by males in foraging activities gives them more time for other activities, especially anti-predator vigilance. Foraging techniques and the proportions of different food types in the diet changed seasonally. Foraging for arthropods was most frequent in the season when arthropod abundance was lowest, resulting in the amount of time spent eating arthropods to vary less across the seasons. Fruits and flowers were not eaten in a direct relationship to availability, but were used more than expected relative to availability when arthropod abundance was reduced. Individuals were more dispersed when foraging compared to other activities. Overall, there was little evidence of any direct foraging benefits for a squirrel monkey from being social.