Male–immature relationships in multi‐male groups of mountain gorillas (Gorilla beringei beringei)

Abstract

We examined the pattern and possible functions of social interactions between adult males and immatures in three free-ranging, multi-male groups of mountain gorillas (Gorilla beringei beringei). Previous studies conducted during the 1970s when groups contained one to three adult males concluded that male-immature relationships were likely to be a form of low-cost paternal investment [Stewart, Mountain gorillas: three decades of research at Karisoke. Cambridge, UK: Cambridge University Press, 2001]. We evaluated whether this hypothesis still held in groups containing six to nine adult males, or if male-immature relationships might serve other functions (e.g. mating effort, kin selection, or alliance building). Overall, we found that immatures spent the most time near, and interacted most with, the alpha silverback. These behaviors peaked during the period when infants were still quite vulnerable but increasing their independence from their mothers. Such findings suggest that parenting effort remains the primary function of male-immature relationships; however, there is some evidence for the mating effort hypothesis as well.

Paternal Relatedness Predicts the Strength of Social Bonds among Female Rhesus Macaques

“…Whether the lack of preferential affiliation with paternal kin in some populations [20], [22], [34], [52] results from the inability to differentiate paternal kin from non-kin remains unclear. On the one hand paternal kin discrimination may not be selected for if large benefits can be reaped from indiscriminate low cost investments [53] which requires that females do not compete in a zero sum game and that the benefits of cooperating are not counterbalanced by kin competition. Perfect paternal kin discrimination may even be selected against by male infanticide [54].…”

Variation in the social organization of gorillas: Life history and socioecological perspectives

“…Among subordinate male mountain gorillas, the probability of philopatry (versus dispersal) is significantly higher if their mother is still in the group . Proximity to their mother could help those males to develop relationships with other adult females and with the dominant silverback . The later age of maturation for western gorillas may reduce the probability that males will reach adulthood in the same group as their mother, which could reduce their probability of creating and maintaining multimale groups.…”

Mothers may shape the variations in social organization among gorillas

“…Those relationships may also be stronger if the sons are with a ‘familiar’ dominant silverback such as their putative father, especially if such familiarity is used as proxy for kin discrimination [47,48]. Silverbacks are considered ‘familiar’ if they were in the group when the potential emigrant was an infant (even if they were not silverbacks at the time).…”