Alpha male replacements and delayed dispersal in crested macaques (Macaca nigra)

Abstract

In species with a high male reproductive skew, competition between males for the top dominant position is high and escalated fights are common between competitors. As a consequence, challenges incur potentially high costs. Selection should favor males who time an alpha male challenge to maximize chances of a successful outcome minimizing costs. Despite the importance of alpha male replacements for individual males, we know little about the timing of challenges and the condition of the challenger. We investigated the timing and process of alpha male replacements in a species living in multi‐male groups with high male reproductive skew, the crested macaque. We studied four wild groups over 6 years in the Tangkoko Reserve, North Sulawesi, Indonesia, during which 16 alpha male replacements occurred. Although unusual for cercopithecines, male crested macaques delayed their natal dispersal until they attained maximum body mass and therefore fighting ability whereupon they emigrated and challenged the alpha male in another group. Accordingly, all observed alpha male replacements were from outside males. Ours is the first report of such a pattern in a primate species living in multi‐male groups. Although the majority of alpha male replacements occurred through direct male‐male challenges, many also took place opportunistically (i.e., after the alpha male had already been injured or had left the group). Furthermore, alpha male tenures were very short (averaging ca. 12 months). We hypothesize that this unusual pattern of alpha male replacements in crested macaques is related to the species‐specific combination of high male reproductive skew with a large number of males per group. Am. J. Primatol. 79:e22448, 2017. © 2015 The Authors. American Journal of Primatology Published by Wiley Periodicals, Inc.

Growing into adulthood—a review on sex differences in the development of sociality across macaques

“…However, male crested macaques do not appear to form affiliative bonds with their offspring, at least not within the first year of life (Kerhoas et al 2016). Given the intense male-male competition in this species, resulting in an extremely low mean alpha tenure of 12 months (Marty et al 2017a), it is possible that males are selected to maximize their mating success rather than investing in bonds towards their genetic offspring. Nevertheless, despite absence of large predators, infant mortality in crested macaques reaches almost 20% in the first year of life (Engelhardt and Perwitasari-Farajallah 2008).…”

“…As reproductive skew and male breeding tenure differ across primate species, future studies may reveal inter-specific differences in kin structure, kin preferences and mechanisms of kin recognition. In crested macaques with a high skew in paternity (Engelhardt et al 2017) and short breeding tenure (Marty et al 2017a), for instance, paternal kin might most likely be peers, potentially resulting in a kin preferences via age proximity only. In contrast, in species with a lower skew and more relaxed breeding tenure, such as rhesus macaques, paternal siblings are not only restricted to peers (Widdig et al 2002), and other kin recognition mechanisms, such as phenotype matching, might have evolved (e.g.…”

Bayesian inference and simulation approaches improve the assessment of Elo-scores in the analysis of social behaviour

“…In order to simulate a change in social hierarchy which might occur in the event of an external rank takeover, for instance as a result of an immigration event (Marty et al, 2015;Cheney et al, 2004), we used an equidistant grid of underlying Elo scores from −6 to 6 with a length of N = 10. The simulation was divided into two periods.…”

Alpha male replacements in nonhuman primates: Variability in processes, outcomes, and terminology

“…For species forming uni‐male, multi‐female groups, alpha male replacements are reported to occur at a rate between 0.07 and 2.07 per year (Janson & van Schaik, ) because of intense competition between resident males and floater males to reproductively monopolize a group of females (Butynski, , ; Henzi & Lawes, ; Hrdy, ; Kvarnemo & Ahnesjö, ; Weir et al, ). New alpha males generally need to defeat the former alpha in order to take up the dominant position within the group and thus they tend to be prime‐aged and in top physical condition (Borries et al, ; Marty, Hodges, Agil, & Engelhardt, ; van Noordwijk & van Schaik, ). Whether or not females disperse in uni‐male, multi‐female groups may also alter the process of alpha male replacement.…”

“…Immigration of young males into existing groups, even at lower ranks, is not an option in all species. In this volume, Marty et al () show that crested macaque ( Macaca nigra ) males face strong resistance when they try to immigrate into new groups, which may force these males to wait to disperse. Once they attain large body size and prime physical condition in their natal group, males may be more successful in challenging for the alpha position in a new group.…”