1Jr. Research Group Primate Sexual Selection, Reproductive Biology Unit, German Primate Center, Göttingen, Germany, 2Courant Research Centre Evolution of Social Behaviour, Georg-August University, Göttingen, Germany, 3Reproductive Biology Unit, German Primate Center, Göttingen, Germany, 4Faculty of Veterinary Medicine, Bogor Agricultural University, Indonesia
Friday 9:15-9:30, Ballroom A
The factors shaping the evolution of male reproductive strategies in primates can be fully understood only by investigating both costs and benefits of such strategies. While mate-guarding has been proven to increase mating and reproductive success of male primates in multi-male groups, little is known about the energetic costs of such behavior. The aim of the study was therefore to quantify these costs using long-tailed macaques as a model. This species is of particular interest in this respect because alpha males mate-guard females to a lesser extent than predicted by the priority of access model. The study was carried out during two reproductive seasons on three groups of wild long-tailed macaques living in the Gunung Leuser National Park, Indonesia. We combined behavioral observations and non-invasive measurements of c-peptides, as an indicator of male energetic status. Males decreased feeding time and fruit consumption during mate-guarding and concurrently decreased vertical locomotion. These results suggest that male long-tailed macaques balanced lowered energy intake by reducing energetic expenditure. Accordingly, we did not find any effect of mate-guarding activity on energetic status. The incomplete monopolization of females by alpha males might thus be a form of an energy management strategy. These management strategies might strongly differ between non-strictly seasonal species, such as long-tailed macaques, and strictly seasonal ones and further studies on both ends of the spectrum are needed. Finally, our results also emphasize the importance of measuring both components of energy balance, i.e. energy intake and expenditure, when investigating energetic costs of reproduction.
This research was supported by the German Research Council (DFG EN 719/2), the Volkswagen Foundation, the Wenner Gren Foundation and the Leakey Foundation.