The Behavioral Responses of Female Mantled Howler Monkeys (Alouatta Palliata) to Loud Call Vocalizations

Abstract

Howler monkeys (Alouatta sp.) use loud call vocalizations for both intra-group and intergroup communication (Oliveira & Ades, 2004; Whitehead, 1989; da Cunha & Byrne, 2006; Holzmann, 2012). While much of the literature focuses on the effect of loud call vocalizations on male behavior, there is not much information about the effect of the calls on female behaviors. To address this gap, we investigated whether female behavioral responses to loud calls were affected by cues suggesting increased invasion risk. We also examined whether females with and without infants responded differently to calls due to maternal concern for infants. In this study, we observed eight troops of mantled howler monkeys (Alouatta palliata) in a dense, fragmented forest. We recorded both the typical behaviors exhibited by the monkeys every ten minutes and the behavioral responses of females to loud calls. Both types of females behaved more vigilantly in response to loud calls than on a normal basis. They also both responded more vigilantly to certain indicators of increased invasion risk. However, females with infants responded more vigilantly to more cues of invasion risk, likely because of their maternal desire to protect their infants. This study contributes to our knowledge of social communication in primates and has implications for the evolution of maternal care.