Costs of mate-guarding in wild male long-tailed macaques (Macaca fascicularis): Physiological stress and aggression

Abstract

Mate-guarding is an important determinant of male reproductive success in a number of species. However, it is known to potentially incur costs. The aim of the present study was to assess the effect of mate-guarding on male physiological stress and aggression in long-tailed macaques, a species in which males mate-guard females to a lesser extent than predicted by the Priority of Access model (PoA). The study was carried out during two mating periods on three groups of wild long-tailed macaques in Indonesia by combining behavioral observations with non-invasive measurements of fecal glucocorticoid (fGC) levels. Mate-guarding was associated with a general rise in male stress hormone levels but, from a certain threshold of mate-guarding onwards, increased vigilance time was associated with a decrease in stress hormone output. Mate-guarding also increased male-male aggression rate and male vigilance time. Overall, alpha males were more physiologically stressed than other males independently of mating competition. Increased glucocorticoid levels during mate-guarding are most likely adaptive since it may help males to mobilize extra-energy required for mate-guarding and ultimately maintain a balanced energetic status. However, repeated exposure to high levels of stress over an extended period is potentially deleterious to the immune system and thus may carry costs. This potential physiological cost together with the cost of increased aggression mate-guarding male face may limit the male's ability to mate-guard females, explaining the deviance from the PoA model observed in long-tailed macaques. Comparing our results to previous findings we discuss how ecological factors, reproductive seasonality and rank achievement may modulate the extent to which costs of mate-guarding limit male monopolization abilities.

Pulling Rank: Military Rank Affects Hormone Levels and Fairness in an Allocation Experiment

“…Our findings seem to be in dissent with previous findings on non-human primates reporting increased basal levels of glucocorticoids in low compared to higher ranked individuals living in stable hierarchies that are maintained non-physically (reviewed in Sapolsky, 2005). They rather support other studies reporting, higher C levels in alpha males (Barrett et al, 2002; Girard-Buttoz et al, 2014). In these studies higher C levels in high ranked individuals were explained by greater metaboloic costs associated with prolonged courtships and mate-guarding activities.…”

Responses to social and environmental stress are attenuated by strong male bonds in wild macaques

“…Several studies, however, failed to replicate the negative effect of aggression received on an individual's physiological stress level (55,(60)(61)(62)(63). Our results suggest that in these latter studies interaction effects in the social buffering mechanism may have blurred the patterns observed and may explain ambiguities between some studies and species.…”

Komodo Dragon Predation on Crab-Eating Macaques at the Rinca Island’s Visitor Centre, Indonesia

“…Secondly, since the macaques are semi-terrestrial on other islands [Richter et al, 2013], we aim to find the degree of terrestrial overlap between the macaques and dragons to quantify Komodo dragon-macaque predation opportunity. We further investigate whether spatial segregation and arboreal strata preference among macaque sex and age classes [Girard-Buttoz et al, 2014] are present in the M. fascicularis in Loh Buaya valley as a potential predation risk variable that may influence population dynamics.…”