Male Takeovers Research Articles

Social network dynamics, infant loss, and gut microbiota composition in female Colobus vellerosus during time periods with alpha male challenges.

The gut microbiota of group-living animals is strongly influenced by their social interactions, but it is unclear how it responds to social instability. We investigated whether social instability associated with the arrival of new males and challenges to the alpha male position could explain differences in the gut microbiota in adult female Colobus vellerosus at Boabeng-Fiema, Ghana. First, we used a data set collected during May-August 2007 and May 2008-2009 that consisted of (i) 50 fecal samples from adult females in eight social groups for V4 16S rRNA sequencing to determine gut microbiota composition, and (ii) demographic and behavioral data ad libitum to determine male immigration, challenges to the alpha male position, and infant births and deaths. Sørensen and Bray-Curtis beta diversity indices (i.e., between-sample microbiota variation) were predicted by year, alpha male stability, group identity, and age. Next, we used a more detailed behavioral data set collected during focal observations of adult females in one group with a prolonged alpha male takeover and three cases of infant loss, to create 12-month versus 3-month 1-m proximity networks that preceded and overlapped the gut microbiome sampling period in that group. The long versus short-term networks were not correlated, suggesting temporal variation in proximity networks. In this group, beta diversity among the five adult females was predicted by similarity in infant loss status and short-term (rather than yearly) 1-m proximity ties. Although the mechanism driving this association needs to be further investigated in future studies, our findings indicate that alpha male takeovers are associated with gut microbiota variation and highlight the importance of taking demographic and social network dynamics into account.

Disappearance of infants following male takeovers in the Belizean black howler monkey (<i>Alouatta pigra</i>)

No abstract

Co-Constructing a Gender–State Entanglement in Canonical Three Kingdoms Fandom: A Discourse-Historical Approach

ABSTRACT Adopting a discourse-historical approach (DHA), we analyse how male influencers and their followers co-construct a gender–state entanglement through social-mediated discussions about a mythologised historical figure, Zhuge Liang, on Bilibili. The analysis discovers that the historical figure is portrayed as a wen–wu masculinity archetype, whose imaginary is modified against current socio-cultural trends and intertextually linked to China’s nation-building project. The masculinist valorisation of the historical figure of Zhuge reiterates the male takeover of nationalist politics as a defining feature of popular cultural production and consumption in post-reform China. The study makes a meaningful contribution to scholarship about Three Kingdoms fandom by showing how past memories and present events converge in Chinese-language social-mediated communication, where heteronormative visions and worldviews are consistently overrepresented.

Gender dynamics in seed systems: female makeover or male takeover of specialized sweetpotato seed production, in Lake Zone Tanzania?

Interest is growing for the development of inclusive seed production models. However, there is limited understanding of gender-based roles and constraints and how these might influence gender relations in seed production. Through a case study on sweetpotato seed production in Lake Zone Tanzania, this article examines men’s and women’s roles in seed production with the introduction of specialized seed practices and a commercial orientation. The study uses data from 17 field-based plot observations and eight sex disaggregated focus group discussions (FGDs) with 33 (51% women and 48% men) decentralized vine multipliers (DVMs). Participatory, gender-based analytical tools were used to obtain an in-depth understanding of gender dimensions and implications of new seed production practices, the resources required and access to those resources. Our findings show that men and women have complementary roles in specialized seed production, and that men increased their involvement in production and commercialization, especially when larger monetary inputs and transactions took place. Women gained new tangible (income) and intangible (knowledge) assets, which enhanced their community status. Women’s contributions to household income became more visible. In conclusion male-takeover did not take place. There were changes in the perceptions around sweetpotato production and gender relations. As women’s contributions to household income became more visible, they were able to negotiate with their husbands on access to key resources to maintain this household revenue stream. We discuss how the new knowledge and skills related to seed production enhanced women’s status in the community. These dynamics initiated changes in gender relations and challenged prevailing community perceptions on gender roles.

Female demographic changes contribute to the maintenance of social stability within a primate multilevel society

Various primate species, including golden snub-nosed monkeys, Rhinopithecus roxellana , form highly complex multilevel social systems. Breeding bands of snub-nosed monkeys maintain stability even though multiple one-male units (OMUs) within a band do not appear to engage in affiliative behaviours among units. As such, female dispersal within breeding bands may be a key factor related to social stability in these complex social systems. However, how individual and group behaviours influence both the formation of this complex social system and the maintenance of social stability within it remain to be fully elucidated. In the current study, based on 16 years of accumulated data, we investigated female dispersal in a wild population of golden snub-nosed monkeys in the Qinling Mountains of China. Using social network analysis and dynamic social modelling, we found that male take-over had no influence on the dominance rank of an OMU, whereas the number of breeding females within an OMU had a significant positive effect on rank. Both the number of breeding females and the number of females entering an OMU had significant positive effects on eigenvector centrality of an OMU. Female dispersal between OMUs decreased the clustering coefficient and reduced the risk of subgroup formation. In addition, female kinship matrices between units were not significantly correlated with association behaviour patterns. Thus, this study sheds light on the internal mechanisms that drive social stability in a complex primate social system. • One-male units in a golden snub-nosed monkey band showed few affiliative behaviours. • Multiple females dispersed among units during the 16-year study period. • Social network analysis showed that female dispersal can maintain social stability. • Female dispersal, not male take-over, affected unit hierarchical rank. • Female kinship did not influence association patterns among one-male units.

Social drivers of maturation age in female geladas.

Female reproductive maturation is a critical life-history milestone, initiating an individual's reproductive career. Studies in social mammals have often focused on how variables related to nutrition influence maturation age in females. However, parallel investigations have identified conspicuous male-mediated effects in which female maturation is sensitive to the presence and relatedness of males. Here, we evaluated whether the more "classic" socioecological variables (i.e., maternal rank, group size) predict maturation age in wild geladas-a primate species with known male-mediated effects on maturation and a grassy diet that is not expected to generate intense female competition. Females delayed maturation in the presence of their fathers and quickly matured when unrelated, dominant males arrived. Controlling for these male effects, however, higher-ranking daughters matured at earlier ages than lower-ranking daughters, suggesting an effect of within-group contest competition. However, contrary to predictions related to within-group scramble competition, females matured earliest in larger groups. We attribute this result to either: 1) a shift to "faster" development in response to the high infant mortality risk posed by larger groups; or 2) accelerated maturation triggered by brief, unobserved male visits. While earlier ages at maturation were indeed associated with earlier ages at first birth, these benefits were occasionally offset by male takeovers, which can delay successful reproduction via spontaneous abortion. In sum, rank-related effects on reproduction can still occur even when socioecological theory would predict otherwise, and males (and the risks they pose) may prompt female maturation even outside of successful takeovers.

Male-Mediated Maturation in Wild Geladas

The timing of female maturation in wild mammals is often constrained by ecological variables that relate to food acquisition. However, maturational timing in female mammals can also respond to social variables. Specifically, the arrival of novel males can accelerate maturation while the presence of related males can inhibit it. Despite studies on more than two dozen mammalian taxa in captivity, evidence for male-mediated maturation has not been systematically demonstrated in any wild population. Here, we report the first evidence of male-mediated maturation in a wild primate, the gelada (Theropithecus gelada). After the arrival of a new breeding male in the group (a male takeover), young females were three times more likely to mature. We then examined these takeover-associated maturations in more detail: some were earlier than expected (a presumptive "Vandenbergh effect," or male-accelerated maturation), some were at the expected age for the average female gelada, and some were later than expected (a presumptive "inbreeding avoidance delay," or father-induced reproductive suppression). An examination of fecal estrogens, which rise just before visible signs of maturation in this species, revealed that male takeovers induced a surge in estrogens for immature females of all ages-even females that did not mature. These are the first data to demonstrate that specific males are associated with the onset of maturation in a wild primate and to provide a possible mechanism for this change. These results suggest that all male-mediated maturation (whether accelerated, on-time, or delayed) may be governed by similar neuroendocrine processes.

Multilevel societies facilitate infanticide avoidance through increased extrapair matings

In mammals characterized by a mating system in which a single male monopolizes reproduction, infanticide is reported to occur following a male take-over, often resulting in females returning to oestrus more rapidly than if their infant has survived. However, over the course of a 17-year study of golden snub-nosed monkeys, Rhinopithecus roxellana, a polygynous colobine species, we found no behavioural or suspected evidence of infanticide. Based on social network and genetic analyses, we found that more than half of the infants were sired as a result of extrapair matings (EPMs). Female golden snub-nosed monkeys initiated EPMs with bachelor or neighbouring resident males. These were considered ‘sneaky’ copulations because they did not occur in the presence of the leader male of the female's one-male unit (OMU). We suggest that through a process of paternity confusion, females decreased the likelihood of infanticide after a male take-over. In contrast, in a group of the same species in which the number of bachelor males was artificially reduced, EPMs were infrequent and four cases of infanticide were observed, three of them following a male take-over. Golden snub-nosed monkeys reside in a large multilevel society that develops by the fusion of several independent OMUs to form a breeding band, which is characterized by increased social cohesion and intrasexual tolerance among leader males. Females play an active role in mate choice, and engage in a diverse set of mating tactics, including counterstrategies such as EPMs to avoid infanticide. These results offer new insights into the diversity of behavioural strategies facilitated by complex social structures in nonhuman primates, as well as other social mammals.

Reproductive strategy of bachelors in a snub-nosed monkey (Rhinopithecus bieti) all-male unit.

Snub-nosed monkeys exhibit a rare multilevel social system composed of several one-male units (OMU) and at least one all-male unit (AMU). The AMU comprises males who are blocked from access to females by resident males in the OMUs, and how these satellite males achieve reproductive success is still unclear. To investigate their reproductive strategies, we focused on the AMU in a band of provisioned black-and-white snub-nosed monkeys (Rhinopithecus bieti) in Yunnan, China. Behaviors that AMU males use to gain access to females (i.e. immigration, male takeover, and sexual interaction with females) were recorded and compared with resident OMU males to explore how AMU bachelors achieve reproductive success when they are denied stable access to females. We found that in response to solicitation from females, adult and sub-adult members of the AMU responded more actively than resident males, and the bachelors actively initiated mating with females when the latter's resident male was temporarily absent. These mating opportunities mostly coincided with the peak mating season in OMUs, and probably allowed bachelors to sire some offspring. We also found that for some AMU adults, taking over an OMU is the main strategy used to gain stable access to females, and these males repeatedly migrate between bands. AMU members therefore show multiple strategies that allow them to gain some degree of reproductive success.

Re-emergence of the leaf clip gesture during an alpha takeover affects variation in male chimpanzee loud calls.

Loud calls are used by many species as long-distance signals for group defense, mate attraction, and inter- and intragroup spacing. Chimpanzee loud calls, or pant hoots, are used in a variety of contexts including group coordination and during male contests. Here, we observed an alpha male takeover in wild chimpanzees (Pan troglodytes verus) during which the leaf clipping gesture re-emerged after disappearing for almost two years in this community. Leaf clipping only occurred in males and was observed almost exclusively prior to pant hoot vocalizations, as has been observed in other chimpanzee communities of the Taï forest in Côte d’Ivoire. Consequently, we hypothesized that leaf clipping may be important for male-male competition by affecting variation in the acoustic properties of male chimpanzee loud calls. We therefore investigated whether pant hoots preceded by leaf clipping differed acoustically from those without, while also testing the influence of social context on pant hoot variation, namely male dominance rank and hierarchy instability, i.e., before, during and after the alpha takeover. We found that pant hoots preceded by leaf clipping were longer, contained more call elements and drum beats, and lower fundamental and peak frequencies. Moreover, during the alpha takeover pant hoots were shorter, contained fewer drum beats and higher fundamental frequencies. Additionally, pant hoot and aggression rates were also highest during the alpha takeover with leaf clipping more likely to occur on days when pant hooting rates were high. Overall social rank had limited effects on pant hoot variation. We suggest that elevated arousal and aggression during the alpha takeover triggered the re-emergence of leaf clipping and the associated acoustic changes in pant hoots. Further research should focus on the potential mechanisms by which leaf clipping is connected to variation in pant hoots and cross-population comparisons of the behaviour.

Context dependence of female reproductive competition in wild chacma baboons

Recent research reveals that female reproductive competition is common and may shape the social and reproductive strategies of female mammals. This study explores the determinants and intensity of female intrasexual conflicts in a wild promiscuous primate, the chacma baboon, Papio ursinus. We tested a suite of hypotheses to assess whether female–female aggression was primarily driven by instantaneous competition for food, mates or paternal care, or aimed at reducing future competition among offspring via reproductive suppression. Behavioural data were gathered from 53 females in two groups over two contrasting 2-year periods (2005–2006, 2013–2014): the first characterized by stability in the male dominance hierarchies, the second by instability induced by several immigration events and male take-overs. In both periods, we found that sexually receptive females received high levels of aggression from other sexually receptive females, consistent with competition over mating opportunities. In the unstable period, females exchanged higher rates of aggression than in the stable period, regardless of reproductive state, but lactating females received most aggression, consistent with higher competition over social access to male partners in response to increased infanticide risk. There was no evidence that aggression between females reflected either competition over food or reproductive suppression. These findings indicate that patterns of aggression between females fluctuate with sociodemographic factors affecting sexual and social access to males and reflect reproductive competition more closely than resource competition in this promiscuous primate society.

Female choice impacts residential male takeover in golden snub-nosed monkeys (Rhinopithecus roxellana).

In primate species with social systems consisting of one-male breeding units (OMUs), resident male takeover represents a major challenge to individual reproductive success and mating strategies. The golden snub-nosed monkey (Rhinopithecus roxellana) is characterized by large multilevel societies (MLS) comprised of several OMUs and all-male units (AMUs); however, the factors and mechanisms associated with resident male takeover, which offer important insight into primate reproduction and social strategies, are still poorly understood. Based on 5-year monitoring data from a free-ranging herd of golden monkeys from the Qinling Mountains in China, we categorized three phases of an OMU, that is, a rising phase, developing phase, and declining phase. The rising and declining phases were unstable periods in which male takeover in an OMU might occur. Factors causing takeover, such as leader male rank, fighting ability, reproduction rate, and affiliation (proximity, allogrooming), were analyzed for males and females and for different OMUs. Results indicated that the new resident male’s fighting ability was lower than that of the former resident male in 23 cases. After replacement, the rank order of the new resident male significantly declined. Females involved in a takeover increased their distance from the resident male and decreased mating frequency during the three months prior to takeover. Females with infants under one-year-old had a marked effect on the specific time of takeover occurrence. These results suggested that female choice was the main factor deciding whether a takeover attempt was successful. Furthermore, rather than male conflict, females more often initiated and affected takeover and outcome, implying that the social status and competitive ability of the males played lesser roles during takeover.

Social and demographic correlates of male androgen levels in wild white-faced capuchin monkeys (Cebus capucinus).

The Challenge Hypothesis, designed originally to explain the patterning of competitive behavior and androgen levels in seasonally breeding birds, predicts that males will increase their androgen levels in order to become more competitive in reproductive contexts. Here we test predictions derived from the Challenge Hypothesis in white-faced capuchin monkeys (Cebus capucinus), a species that has somewhat seasonal reproduction. We analyzed demographic and hormonal data collected over a 5.25-year period, from 18 males in nine social groups living in or near Lomas Barbudal Biological Reserve, Costa Rica. Alpha males had higher androgen levels than subordinates. Contrary to our predictions, neither the number of breeding-age males nor the number of potentially fertile females was obviously associated with androgen levels. Furthermore, male androgen levels were not significantly linked to social stability, as measured by stability of male group membership or recency of change in the alpha male position. Androgen levels changed seasonally, but not in a manner that had an obvious relationship to predictions from the Challenge Hypothesis: levels were generally at their lowest near the beginning of the conception season, but instead of peaking when reproductive opportunities were greatest, they were at their highest near the end of the conception season or shortly thereafter. This lack of correspondence to the timing of conceptions suggests that there may be ecological factors not yet identified that influence ifA levels. We expected that the presence of offspring who were young enough to be vulnerable to infanticide during an alpha male takeover might influence androgen levels, at least in the alpha male, but this variable did not significantly impact results.

Human–wildlife conflict, benefit sharing and the survival of lions in pastoralist community‐based conservancies

Summary Like many wildlife populations across Africa, recent analyses indicate that African lions are declining rapidly outside of small fenced areas. Community conservancies – privately protected areas that engage community members in conservation – may potentially maintain wildlife populations in unfenced pastoralist regions, but their effectiveness in conserving large carnivores has been largely unknown until now. We identify drivers of lion survival in community conservancies within the Masai Mara ecosystem, Kenya, applying mark–recapture analyses to continuous sight–resight surveys. We use the number of livestock and human settlements as proxies for potential human–lion conflict whilst controlling for environmental variables and lion socioecology. Average lion densities within the Mara conservancies between 2008 and 2013 (11·87 lions 100 km−2) were 2·6 times higher than those previously reported in 2003. Survival rates varied amongst prides and were highest for lions utilizing central regions of conservancies. The number of livestock settlements (bomas [corrals] and manyattas) that were not members of a conservancy, and that fell within a pride home‐range, had a large negative effect on female survival and was the most influential external predictor in models. These non‐conservancy settlements accounted for 37·2% of total observed variation in survival, whereas conservancy settlements, which benefit financially from wildlife through their membership, had no effect on lion survival. Internal drivers of survival agreed with known ecology and social behaviour including age plus a negative effect of male takeovers on cub survival <6 months. Vegetation cover, prey availability and the density of grazing livestock within a pride's range did not explain patterns in lion survival. Synthesis and applications. We show that lion densities have increased substantially within the Mara conservancies over the last decade and suggest that the creation of community conservancies has benefitted their survival. This suggests that lions can survive outside of fenced areas within pastoral regions if communities gain benefits from wildlife. We highlight the importance of expanding existing conservancies beyond their current geographical and political scope and forming buffer zones if wildlife ranges outside them. We suggest that changing attitudes to predators should be a key goal of community‐based conservancies. Further work is recommended to identify what specific aspects of conservancy membership promote lion survival.

Male Infanticide in the Golden Snub-Nosed Monkey (Rhinopithecus roxellana), a Seasonally Breeding Primate

In nonhuman primates, infanticide by adult males can occur when the leader male is ousted from a one-male, multifemale group, or when male dominance rank changes within a multimale, multifemale group. According to the sexual selection hypothesis, this behavior may be adaptive if perpetrators increase their reproductive success by killing unrelated, unweaned infants, thus shortening the interbirth interval of the mother, and then siring her next infant. Under an alternative hypothesis, infanticide is a byproduct of aggressive male–male competition and these predictions do not hold. Direct observations of the context surrounding infanticide in free-ranging primate populations that allow a test of these predictions are rare. Here, we document four cases of male infanticide and report paternity data for a group of golden snub-nosed monkeys (Rhinopithecus roxellana) at Shennongjia, China. Three cases of infanticide by new leader males supported the predictions of the sexual selection hypothesis, while another provides partial support for the sexual selection hypothesis, but can also be explained via a nonadaptive hypothesis. In this latter case, a male from an all-male group killed an infant during an aggressive episode that appeared to be accidental, as it took place 7 mo before a male takeover happened, and the perpetrator did not obtain any reproductive advantage. We conclude that most male infanticide events in golden snub-nosed monkeys are consistent with the adaptive selection sexual hypothesis.

Consequences of a male takeover on mating skew in wild Sanje mangabeys.

Among primate species living in multimale-multifemale groups, the number of receptive females may determine the rank of the lowest male that copulates (priority of access model, or PoA [Altmann SA. 1962. A field study of the sociobiology of rhesus monkeys, Macaca mulatta. Annals of the New York Academy of Sciences 102:338-435]). Factors, such as temporary instability in the hierarchy and female behavior can, however, affect high-ranking males' ability to monopolize females, reducing mating skew and causing the hierarchy to depart from predictions of PoA. Here, I use behavioral data collected over a 22-month period on a wild group of Sanje mangabeys (Cercocebus sanjei) to examine the effect of a takeover by two immigrating males who became α and β in the hierarchy, and of female behavior on male mating skew. Data on male agonistic interactions were collected on nine males using ad libitum observations, while information on male mating success (i.e., daily proportion of ejaculatory copulations with the focal female) was collected through focal follows of 12 sexually receptive females. Before the takeover, the hierarchy was stable and highly skewed, with the α-male monopolizing up to 75% of copulations. At this time, however, mating skew did not follow the predictions of PoA. During the takeover, from the time one of the newly immigrant males replaced the α until the second immigrant male became the new β, the stability of the hierarchy dropped significantly and mating was no longer skewed. Accordingly, the top two ranking males at that time (i.e., the new α and former β) accounted for only 33% of copulations. After the takeover, rank stability increased, and mating skew followed the PoA. Female mating solicitations also had a significant positive effect on male mating success, and may have contributed to the deviation from the PoA. This study demonstrates that temporary rank instability decreases high-ranking males' ability to monopolize copulations, causing a departure from the predictions of the PoA. Am. J. Primatol. 79:e22532, 2017. © 2016 Wiley Periodicals, Inc.

The influence of male takeovers on female dispersal in Colobus vellerosus.

Male takeovers affect male tenure, female mate choice and ultimately, individual reproductive success in group-living primates. In social systems with female philopatry and high male reproductive skew, male takeovers largely determine female mate choice, whereas in species with female dispersal, females have the option of deserting a new male. We focused on a species with facultative female dispersal to investigate which factors promote female desertion of males after takeover, using 15 cases (12 for which we have complete data on the takeover process and the female dispersal outcome). These cases took place in nine groups of Colobus vellerosus between 2001 and 2013 at the Boabeng-Fiema Monkey Sanctuary, Ghana. Quick takeovers were usually achieved by single adult males and were never followed by female dispersal. Slow takeovers involved several males, and these takeovers were regularly accompanied by female emigration. Infant attacks and infanticide by males occurred during both kinds of takeovers, but females with dependent offspring never dispersed, regardless of whether their infant was attacked or killed by the new male(s). Subadult females, who were not constrained by the presence of infants, dispersed more often after slow takeovers than after quick takeovers. Whether female dispersal post-takeover is an expression of female mate choice, or occurs to avoid the social upheaval surrounding slow takeovers, remains to be investigated. Am. J. Primatol. 79:e22436, 2017. © 2015 Wiley Periodicals, Inc.

Male-directed infanticide in spider monkeys (Ateles spp.).

Infanticide is considered a conspicuous expression of sexual conflict amongst mammals, including at least 35 primate species. Here we describe two suspected and one attempted case of intragroup infanticide in spider monkeys that augment five prior cases of observed or suspected infanticide in this genus. Contrary to the typical pattern of infanticide seen in most primate societies, where infants are killed by conspecifics independent of their sex, all eight cases of observed or suspected infanticide in spider monkeys have been directed toward male infants within their first weeks of life. Moreover, although data are still scant, infanticides seem to be perpetrated exclusively by adult males against infants from their own social groups and are not associated with male takeovers or a sudden rise in male dominance rank. Although the slow reproductive cycles of spider monkeys might favor the presence of infanticide because of the potential to shorten females' interbirth intervals, infanticide is nonetheless uncommon among spider monkeys, and patterns of male-directed infanticide are not yet understood. We suggest that given the potentially close genetic relationships among adult males within spider monkey groups, and the need for males to cooperate with one another in territorial interactions with other groups of related males, infanticide may be expected to occur primarily where the level of intragroup competition among males outweighs that of competition between social groups. Finally, we suggest that infanticide in spider monkeys may be more prevalent than previously thought, given that it may be difficult for observers to witness cases of infanticide or suspected infanticide that occur soon after birth in taxa that are characterized by high levels of fission-fusion dynamics. Early, undetected, male-biased infanticide could influence the composition of spider monkey groups and contribute to the female-biased adult sex ratios often reported for this genus.

Does hierarchy stability influence testosterone and cortisol levels of bearded capuchin monkeys (Sapajus libidinosus) adult males? A comparison between two wild groups

Testosterone and cortisol are hormones expected to play a major role in competitive behaviours (i.e. aggression), and are related to rank and hierarchical stability. Through a non-invasive technique, we analyzed faecal testosterone (FTM11Fecal testosterone metabolites.) and cortisol (FCM22Fecal cortisol metabolites.) metabolites of dominant and subordinate males from two wild groups of bearded capuchin monkeys. One group had a stable dominance hierarchy while the other had an unstable hierarchy, with a marked conflict period related to a male take-over. In the unstable hierarchy group (1) the dominant male had higher FTM peaks than subordinates, and (2) basal FTM levels were higher than in the stable group. These findings are in accordance with the Challenge Hypothesis and rank-based predictions, and confirm that in Sapajus libidinosus hierarchy stability, social status, aggression rates and testosterone are closely related. Dominants of both groups had higher basal and peak FCM levels, suggesting that in S. libidinosus the dominant male has a higher allostatic load than subordinates, related to his role in protection against predators, intragroup appeasement, and control of food sources. Finally, we suggest that males of S. libidinosus are resistant to testosterone suppression by cortisol, because in the unstable group in spite of an increase in FCM there was also an increase in FTM during the conflict period.This article is part of a Special Issue entitled: Neotropical Behaviour.

Male Takeover and Infanticide in Nilgiri Langurs Semnopithecus johnii in the Western Ghats, India

Male takeover and infanticide are a widespread phenomenon among non-human primates, observed mostly in species with a relatively longer lactation in relation to gestation. In this study, we report for the first time an episode of male takeover and infanticide, and the rarely reported occurrence of an all-male band and female dispersal, in Nilgiri langurs, Semnopithecus johnii, in the Western Ghats, India. The new male was a member of an all-male band. After the takeover, the resident male and 3 juvenile males left the group and joined the all-male band. A female whose infant was killed was found missing after some days. There were significant changes in the patterns of social interactions among the resident group females soon after the male takeover, wherein the females spent less time on social interactions as compared to before and after the episode of takeover. The new male rarely interacted with the females soon after the takeover. We also observed that the resident group shifted its home range to a poorer quality habitat.