Social factors influencing natal dispersal in male white‐faced capuchins (Cebus capucinus)

Abstract

White-faced capuchin males disperse from their natal group at around 4.5 years of age, but there is much variation in dispersal timing: our youngest confirmed disperser was 19 months and the oldest 11 years old. In this study, we investigate possible factors influencing dispersal decisions in this species. Between 1983 and 2010, 64 males were born into three study groups in Santa Rosa National Park, Area de Conservación Guanacaste, and Costa Rica. As of August 2010, 21 died or were presumed dead (<14 months), 13 remained natal residents, and 30 were presumed dispersers. We used backward logistic regression to identify proximate factors that predict the occurrence of male natal dispersal. The occurrence of a takeover (significant positive association) and group size (nonsignificant negative association) were included in the model. Male age, number of maternal brothers, and number of adult males were not significant predictors of natal dispersal. The resultant model correctly classified 97% of dispersed and 89% of resident natal males, for an overall success rate of 95%. The occurrence of a group takeover was the strongest predictor of male dispersal, with natal males being 18.7 times more likely to disperse in the context of a group takeover than during peaceful times. A linear regression model showed that the tenure length of a male's probable father influences the age of natal dispersal, explaining 15% of the observed variation in age. However, when our oldest disperser was removed (an outlier) this effect disappeared. Collectively, these results indicate that group instability, as evidenced by the occurrence of a takeover, shorter tenure length of a natal male's father, and smaller group size, triggers natal dispersal in this species while the converse leads to a delay. These data add to our growing evidence of the enormous impact that takeovers have on the behavioral ecology of this species.

Impact of personality traits and early life experience on timing of emigration and rise to alpha male status for wild male white-faced capuchin monkeys (Cebus capucinus) at Lomas Barbudal Biological Reserve, Costa Rica

“…the probable father, though genetic paternity was not known in that data set); this variable explained 15% of the variance in their model, but was nonsignificant when one outlier was removed (Jack et al, 2011). At Santa Rosa, natal dispersal was 18.7 times more likely to occur in the aftermath of an alpha male turnover than at other times (Jack et al, 2011) enough to participate in intergroup encounters. We have even seen sons co-emigrate with their father after the father is deposed from the alpha position.…”

“…There, the best predictor of age at dispersal is the length of time that a male has co-resided with the male who was alpha at the time of his conception (i.e. the probable father, though genetic paternity was not known in that data set); this variable explained 15% of the variance in their model, but was nonsignificant when one outlier was removed (Jack et al, 2011). At Santa Rosa, natal dispersal was 18.7 times more likely to occur in the aftermath of an alpha male turnover than at other times (Jack et al, 2011) enough to participate in intergroup encounters.…”

“…In all cases except for peaceful inheritance by a resident, infanticide was a common outcome. Previous work on the timing of natal dispersal in white-faced capuchins at the nearby site of Santa Rosa has found that natal dispersal is far more likely during the social instability period characterizing the aftermath of an alpha male takeover (Jack et al, 2011).…”

Inbreeding risk, avoidance and costs in a group-living primate, Cebus capucinus

“…These males also often retain their top rank for tenures exceeding five years, which corresponds to the age at which their daughters reach reproductive age. Importantly, long male alpha tenures facilitate co-residency of paternal half siblings and full siblings of varied ages, as natal males are less likely to migrate out of their group if there is stability in the alpha position (Jack et al 2011) and if their fathers are still present (Perry et al 2017). Although male migration from natal groups decreases the likelihood of inbreeding by siblings, adult and sub-adult males often do co-reside with their sexually mature sisters (Godoy 2010), and males have been known to become alphas of their own natal groups .…”

Individual dispersal decisions affect fitness via maternal rank effects in male rhesus macaques

“…In primates, leaving or staying in the natal group has been related to group size and composition, whereby male dispersal in many species seems to be driven by the resulting mating opportunities (e.g. white-faced capuchins Cebus capucinus 14; savanna baboons Papio cynocephalus spp 15; black-faced lion tamarins Leontopithecus caissara 16). In female-dispersing mountain gorillas ( Gorilla beringei beringei ), on the other hand, natal dispersal appeared to be driven by infanticide avoidance, with natal females being more likely to leave one-male groups, where infanticide risk is higher than in multi-male groups17.…”