Lack of Evidence for Energetic Costs of Mate-Guarding in Wild Male Assamese Macaques (Macaca assamensis)

Mate-guarding is a widespread and efficient male strategy for increasing paternity success. The inability to guard entire female receptive phases or complete lack of mate-guarding has been explained by energetic constraints posed on males. The energetic costs per unit time a male can afford to suffer are thought to be lowest in year-round breeding species in marginal habitats and highest in seasonally breeding species in rich habitats. Here we test the prediction that mate-guarding is energetically costly in seasonal breeders in marginal habitats. We observed all males in one group of wild Assamese macaques (Macaca assamensis) for two 4-mo mating seasons and recorded activity and travel paths via focal animal sampling, physical condition via visual inspection, and collected feces for analysis of glucocorticoid levels. Generalized linear mixed model (GLMM) analyses did not reveal an effect of mate-guarding on time spent feeding or moving or on distance traveled, travel speed, directedness of travel, or glucocorticoid levels. This lack of mate-guarding costs was consistent with the lack of a relationship between individual time spent mate-guarding and change in physical condition over the mating season. Within the limitations of our study the results do not support the idea that seasonally breeding males in marginal habitats face energetic costs of mate-guarding. With others we suggest instead that though these costs may be found in species where strength, size, and mass predict rank, mating, and reproductive success, males may not engage in costly mate-guarding in species such as Assamese macaques where also smaller, weaker males may attain high social status via political coalitions or other routes alternative to direct contest over guarded females.