Monogamous systems are rare in mammals, including primates, and understanding how monogamy evolved and is maintained has been a goal of research for the past 30 years. Of special interest has been the pair bond: why should one male and one female form an exclusive and enduring attachment? Explanations have generally centered on three categories of benefits: joint defense of resources, male mating exclusivity, and the delivery of male services that increase female reproductive success (e.g. paternal care, protection from predators, infanticide protection).
Over 13 months at the Los Amigos Research Center and Conservation Area in the Peruvian rainforest, this project will attempt to differentiate among these potential benefits by examining the sensitivity of the bond between pairmates of brown titi monkeys (Callicebus brunneus), a highly vocal and territorial species characterized by extensive paternal care and a strong attraction between the adult male and female of a family group. Through the use of observational sampling and playbacks of unfamiliar calls (simulating intruders), this study will quantify the behaviors that have indicated pair-bondedness in captive titi monkeys and correlate changes in these behaviors with differences in the physical environment (i.e. fruit abundance, territory location) and social environment (i.e. proximity of a sexual competitor to the subject's pairmate). As one of the few monogamous primates in which pairs are unambiguously bonded, Callicebus is ideally suited for the questions of this study, which will be addressed with a novel combination of detailed behavioral data, food-abundance data, and playbacks experiments.
This research will be part of a long-term collaborative monitoring and research project between plant and animal biologists that will directly inform conservation activities in southwestern Amazonia, one of the most biologically diverse regions in the world. In addition to directly supporting the training of a U.S. graduate student, the funding for this study will help to increase scientific capacity through collaborations with Peruvian scientists and non-governmental organizations as well as the training of local staff, community members, and Peruvian graduate and undergraduate students in primate natural history and general methods of behavioral ecology.
