Reproductive status affects the feeding ecology and social association patterns of female squirrel monkeys (Saimiri collinsi) in an Amazonian rainforest.

Abstract

When making foraging decisions, female primates may follow specific behavioral strategies that reflect their reproductive state. Lactation is considered the most energetically costly phase for females, but we argue that gestation is also energetically expensive for squirrel monkeys. In this study, we examined whether female squirrel monkeys (a seasonally breeding primate) in different reproductive phases showed significant differences in their foraging ecology. We sampled two wild groups of squirrel monkeys (Saimiri collinsi) using the focal animal method, during 12 months (June 2014 to May 2015). During this time, we quantified the effect of reproductive state (mating, gestation, and lactation) and sex (females vs. males) on activity budgets, foraging efficiency, dietary composition, and nearest neighbors. We found significant effects of both sex and reproductive phase on the mean proportion of time spent foraging, resting, traveling, and being social. Females consumed more insects than did males at all times; among females, time spent eating prey and fruit varied according to reproductive state. These data suggest that, due to their life history and seasonal breeding, reproduction is a costly activity for female Saimiri, and not only during lactation. Therefore, adopting the appropriate behavioral strategies is essential to reduce energetic deficits in females.