Inter-Mount Social Interactions During Heterosexual and Homosexual Consortships in Japanese Macaques

In this study, we examined whether female Japanese macaques ( Macaca fuscata ) exhibited male-typical patterns of inter-mount social behaviour during homosexual consortships. Data were collected on heterosexual and homosexual consortships from a population of free-ranging Japanese macaques in Arashiyama, Japan. Inter-mount intervals were defined as the period between two consecutive mounts. A total of 3374 heterosexual inter-mount intervals and 1412 homosexual inter-mount intervals were analysed. We examined nine different categories of inter-mount behaviour. Sex differences between heterosexually consorting males and females existed for three of the inter-mount behaviours we examined (i.e. ventral-to-dorsal orientation, aggression directed toward third party individuals, tree-shaking displays). The subordinate female partners in homosexually consorting pairs exhibited some sex-atypical inter-mount behaviours. This sex-atypicality did not appear to reflect generalized developmental canalization in the direction of a male-typical suite of behaviours. Rather, the observed behavioural sex-atypicality could be best explained in terms of the unique alliance-related dynamics that characterized homosexual consortships in Japanese macaques.     

Courtship behaviour in Japanese macaques during heterosexual and homosexual consortships

Female Japanese macaques (Macaca fuscata) in the Arashiyama population near Kyoto, Japan, are unusual, in that they exhibit what many would consider to be male-typical sexual characteristics. Specifically, they mount other females within the context of temporary, but exclusive, sexual relationships (i.e., homosexual consortships) and they sometimes exhibit a preference for female sexual partners, even when given the choice of a sexually motivated male alternative. In this study, we examined whether female Japanese macaques also exhibited male-typical patterns of courtship behaviour during homosexual consortships. Data were collected on courtship behaviour during heterosexual and homosexual consortships in free-ranging Japanese macaques from the Arashiyama (Japan) population. We analyzed the occurrence of 12 different courtship behaviours during 3374 heterosexual inter-mount intervals and 1412 homosexual inter-mount intervals. Sex differences between heterosexually consorting males and females existed for only two of the 12 courtship behaviours we investigated: inclined-back presentations and sexual vocalizations. Dominant and subordinate homosexually consorting females were sex-typical in their expression of inclined-back presentations and sexual vocalizations. Consequently, facultative same-sex sexual partner preference, mounting and consortships do not co-occur with male-typical patterns of courtship behaviour in female Japanese macaques.     

Skewed sex ratios and female homosexual activity in Japanese macaques: An experimental analysis

In this paper we present the results of a behavioral experiment conducted to test whether homosexual consortships and sexual solicitations among female Japanese macaques (Macaca fuscata) increase in the context of operational sex ratios that are heavily skewed towards females. The study involved a baseline period of observation on an intact social group which had a female-biased sex ratio typical of this species. During the experimental period which followed, we created a sub-group with an operational sex ratio that was heavily skewed towards females. Compared to the baseline period, females solicited significantly more same-sex individuals for sex and formed significantly more homosexual consortships during the experimental period of the study. Females did not appear to engage in homosexual activity during the study's experimental period simply because they lacked heterosexual alternatives. Instead, we suggest that an abundance of certain types of preferred, same-sex sexual partners and/or a scarcity of opposite-sex sexual competitors best account for the increased levels of female homosexual behavior observed at this time.     

Physiological and social influences on mounting behavior of troop-living female monkeys (Macaca fuscata)

Female mounting behavior was studied in a troop of Japanese macaques during one breeding season. Of 79 sexually active females, mounting behavior during consortships was shown by 50 females; 13 only with males, 20 with both males and females, and 17 only with females. Several factors associated with reproductive state influenced the expression of mounting activity. Recency of parturition influenced the mounting by females regardless of the type of partner. Females that had not given birth the previous spring (four to six months prior to the period of observation) were more likely both to mount partners and to produce an infant the following spring. These findings suggest the existence of a common factor, perhaps associated with lactation, inhibitory both to expression of mounting and to female fertility. Additionally, females that mounted were more likely to do so in consortships that followed than in those that preceded conception. This last finding suggests that, in this social context, the endocrine conditions of early pregnancy facilitated mounting to a greater extent than those associated with the cyclic ovary. Separate statistical analyses examined possible influences of age, dominance rank, and kinship on the likelihoods of mounting and being mounted. None of these factors influenced female mounting. Results suggest that the expression of mounting by females was more influenced by reproductive state than by social characteristics of the partner.     

Interactions Between Third Parties and Consortship Partners in Tonkean Macaques (<Emphasis Type="Italic">Macaca tonkeana</Emphasis>)

Sexual competition is potentially disruptive for the cohesion of social groups because stress and conflicts can extend to other group members. The displays and interactions of sexual partners are liable to influence the behavior of group-mates, which may need to observe them to anticipate possible consequences. We studied 2 captive groups of Tonkean macaques (Macaca tonkeana) to test whether group-mates pay more attention to consort partners, modify their activities and social interactions, and exhibit signs of stress during periods of sexual consortships. We found that group-mates approached the top-ranking male more frequently and were more frequently oriented toward the consort pair at the time of consortship than at other times. Group-mates spent less time sleeping, and devoted less time to manipulating the environment and more time to monitoring during consortship. This indicates that consortships may incur costs in individuals not involved in sexual competition. However, Tonkean macaques did not exhibit any signs of increased stress during consortship periods, as their rates of scratching and yawning did not differ between consortship and nonconsortship periods. This study shows that not only direct competitors but also other individuals monitor the behavior of sexual partners. It is likely that group-mates obtain information this way about ongoing action, and take decisions accordingly.     

Sex differences in sexual partner acquisition, retention, and harassment during female homosexual consortships in Japanese macaques

Female Japanese macaques (Macaca fuscata) in certain populations are unusual in that they exhibit male-typical patterns of mounting behavior and sexual-partner preference. The goal of this study was to determine whether female Japanese macaques, from one such population, employ male-typical behavioral tactics to disrupt existing homosexual consortships, as well as to acquire and retain same-sex sexual partners. "Harassment" of homosexual consortships occurred when a sexually motivated, third-party male or female interrupted a consorting female couple by displacing or aggressing them. Sexual harassment was a male-typical strategy for disrupting existing homosexual consortships, but was rarely performed by females. "Intrusions" occurred when a male or female competitor attempted to acquire exclusive access to a female engaged in a homosexual consortship by targeting that female as the focus of competition and her partner as his/her competitor. "Sexual coercion" occurred when one individual alternately sexually solicited and aggressed another individual as part of the same behavioral sequence during an intrusion. Males employed consortship intrusions and sexual coercion when they attempted to acquire female sexual partners that were already engaged in homosexual consortships, but females rarely did so. However, females did employ male-typical patterns of aggressive competition and sexual coercion to retain same-sex sexual partners when confronted with male competitors' attempts to usurp those partners. These results indicate that female sexual activity during homosexual consortships is not uniformly "masculine" in expression, but rather is a mixture of male- and female-typical behaviors.     

雄性短尾猴个体特征与临时配偶关系研究

多雄多雌的灵长类社会群体中,性成熟的雄性和雌性形成临时性的配偶关系（Consortship）是极其显著特征,但这种关系对个体的交配和繁殖成功作用缺少深入研究。本研究以栖息于安徽黄山的短尾猴YA1群为研究对象,采用全事件取样法（All occurrences recording）、目标动物取样法（Focal animal sampling）以及行为取样法（Behavioral sampling method）记录个体间的社会行为、雄性的配偶数量和临时配偶关系的持续时间,对雄性短尾猴临时配偶关系的基本特征与适应策略进行了初步探讨。研究期间,雄性个体的顺位发生替换,在替换前后,处于高顺位的雄性个体始终拥有最多的配偶数量以及形成的临时配偶关系的持续时间最长,并且雄性个体的顺位与临时配偶关系呈正相关关系（顺位变化前：配偶数量：P = 0.010;持续时间：P = 0.014;顺位变化后：配偶数量：P = 0.032;持续时间：P = 0.035）;雄性个体的年龄与临时配偶关系无显著相关性（配偶关系：P = 0.150;持续时间：P = 0.511）;雄性个体在群体中生活的时间与临时配偶关系呈显著正相关（配偶数量：P = 0.034;持续时间：P = 0.023）;雄性个体的社会关系与临时配偶关系呈显著正相关（顺位变化前：配偶数量,P = 0.013;持续时间,P = 0.001;顺位变化后：配偶数量,P < 0.001;持续时间,P = 0.003）。研究结果表明：雄性个体的顺位、在群体中生活时间以及社会关系对临时配偶的形成起主要作用,这为进一步阐明雄性行为策略与临时配偶关系提供新的科学依据。     

Homosexual behaviour and female-male mounting in mammals—a first survey

Information from the literature is given on the presence or absence of homosexual behaviour and female-male mounting in 125 species of mammals, both captive and wild. Such behaviour occurs in the male and often female young of many species soon after their birth. It is more common in young, often in play, than in adults. Adult homosexual behaviour is widespread in male and female mammals (recorded in 63 and 71 species respectively), but common in few species. In males it is most likely to be correlated with dominance and thus to occur in species with hierarchies such as terrestrial monkeys and members of the sheep and goat tribe. In females it is often correlated with sexual condition; a female in heat most often mounted another female, and one in heat was next most likely to be mounted by another female. Anoestral females rarely mounted other anoestral females. Females of 43 species mounted males, which often excited them sexually. Captive mammals tended to mount animals of the same sex more often than did wild ones when comparative data were available. Domestic animals also mounted more man did wild ones, with several exceptions. Some phylogenetic groups of animals displayed similar degrees of homosexual mounting, but there was often considerable variation between closely related species. Nor could homosexual mounting be always correlated with the social structure of a group. The four reasons for, or contexts of, homosexual and female-male mountings were social play (in 34 species), aggression (19 species), sexual excitement (36 species), and physical contact—non-play (30 species). This last category included a state of tension, getting attention, greeting, grooming, caressing, reassurance and appeasement. There was some overlap between categories. Homosexual pair-bonds occur in captive mammals and have been observed throughout the year in non-captive female Japanese monkeys.     

The relationship of male-male mounting to mate choice and sexual performance in male dairy goats

Rearing of male farm animals in unisexual groups has been implicated as a factor contributing to the failure of many males to breed as adults. The present study examines the relationship of male-male mounting in yearling dairy goats to subsequent mate preferences and sexual performance.Twenty-four sexually inexperienced male dairy goats, representing the Alpine, LaMancha, Saanen and Toggenburg breeds, were observed for male-male mounting in their home enclosure and then tested for mate choice and sexual performance when exposed to male and female (estrous and diestrous) stimulus animals. Their sexual behavior was compared with 7 adult goats with previous breeding experience.In the mate choice-sexual performance tests, 4 sexually inexperienced goats (17%) were sexually inactive, 6 (25%) mounted both male and female stimulus animals and 14 (58%) mounted only the female stimuli. Mate choice and sexual performance of the 20 sexually active males was not related to the number of male-male mounts initiated or the number of different males mounted in their home enclosure. However, the goats that received the greatest number of mounts in their home pen tended to be bisexual (would mount both male and female stimulus animals) in the mate choice tests. Males that were sexually inactive in mate choice-sexual performance tests repeatedly mounted the same male during home pen observations. Except for ejaculation frequency, the sexual performance of the sexually naive and experienced goats was similar. Goats of the Saanen breed were favored recipients of mounts from other males. There was no relationship between the number of male-male mounts performed and received.It was hypothesized that the reproductive failure of many male farm animals reared in all-male groups may be more closely related to the formation of specific sexual attachments to other males rather than the frequency with which they exhibit homosexual behaviors.     

白马雪山自然保护区响古箐滇金丝猴（Rhinopithecus bieti）的交配行为

灵长类交配模式是灵长类社群结构和婚配制度的重要表征之一,其研究有助于了解灵长类社群结构和两性交配策略。2013年11月至2014年10月,我们对云南白马雪山国家级自然保护区一人工辅助投食滇金丝猴群进行了观察研究,采用焦点动物取样法和全事件记录法收集了雌雄个体的交配相关的行为数据,主要包括邀配对象、交配过程、持续时间和回合数,以及参与交配的雌雄对在交配结束后的相互理毛的持续时间和回合数。研究结果表明：研究群滇金丝猴全年均有交配行为,交配高峰期在7-9月,两性参与交配的积极性和对季节变化的响应不同;交配主要由雌性通过邀配发动（76%）,交配高峰期也是雌性邀配的高峰期;雄性爬跨频次（年均0.43次/月,n=5）和射精爬跨比（年均19%,n=5）则在全年无显著变化。交配行为发生的典型表现为：雌性通过小跑或跳跃进入雄性视线范围内,爬伏呈臀向雄性邀配;雌猴爬伏时离雄猴的远近距离不同（<1m vs. 2-5m ： 69% vs. 31%）会影响其邀配成功率（<1 m vs. 2-5 m ：68% vs. 40%）;若一次邀配失败,雌猴可能会连续爬伏邀配（最多4次）,连续多次邀配的成功率显著高于单次邀配（79% vs. 52%）。交配结束后雌性会主动为雄性理毛,但雌性主动理毛与交配是否射精无关。     

The reproductive behavior of golden monkeys in captivity (Rhinopithecus roxellana roxellana)

The reproductive behavior of two captive harem breeding groups of golden monkeys was observed over one mating season and compared to non-seasonal reproductive behavior. Observation of over two thousand sexual interactions suggests that 1) females were responsible for 95% of all sexual solicitations (proceptive behavior), of which the typical pattern was prostration, while males were responsible for only 5%; 2) 17% of female solicitations were interrupted by another female; 3) 52% of female solicitations resulted in mounting by males; 4) the frequencies of solicitations and receipt of mounts and ejaculations varied greatly among females; 5) the frequency of ejaculations, the ratio of ejaculations to mountings, and ejaculation patterns were different between two males, and 6) the golden monkey is a seasonal breeding animal.     

Analysis of tufted capuchin (Cebus apella) courtship and sexual behavior repertoire: changes throughout the female cycle and female interindividual differences

Sexual solicitations and initiative (proceptivity, sensu Beach [1976] Horm Behav 7:105-138) are important components of the sexuality of females of many primate species. In the tufted capuchin (Cebus apella), female proceptivity characterizes the species' mating system. In study 1, we defined and discussed 20 behavioral patterns based on the observation of 6 females and 5 males living in two social groups. In study 2, each behavior, including mounting activity, was quantitatively assessed during the periovulatory and nonperiovulatory cycle phases of 4 females, detected on the basis of urinary progestin levels (N = 20 ovulatory cycles, 5 for each female); moreover, we monitored changes in females' social interactions (agonism, grooming activity, and play). Nine of the behaviors typically used by the female during courtship and in sexual interactions showed a dramatic increase during the periovulatory phase. Though males mounted females at an apparently higher rate during the periovulatory than the nonperiovulatory phase, the difference was not significant. However, when adult male mounting is separated into those which occur within play and nonplay contexts, there is a significant periovulatory phase effect for mounts not associated with play. Females groomed adult males at the same rate throughout the cycle. Agonism and play did not show any phase effect; however, females' avoidance of adult males significantly increased during the periovulatory phase. Finally, each female made a statistically different use of the behavioral repertoire by performing some behaviors more than others. This variability among females during courtship calls for further research into whether it affects mating success.     

Welcome Back: Responses of Female Bonobos (Pan paniscus) to Fusions

In species with a high degree of fission-fusion social dynamics, fusions may trigger social conflict and thus provide an opportunity to identify sources of social tension and mechanisms related to its alleviation. We characterized behavioral and endocrine responses of captive female bonobos (Pan paniscus) to fusions within a zoo facility designed to simulate naturalistic fission-fusion social dynamics. We compared urinary cortisol levels and frequencies of aggression, grooming and socio-sexual interactions between female bonobos while in stable sub-groups and when one “joiner” was reunited with the “residents” of another sub-group. We hypothesized that fusions would trigger increases in aggression and cortisol levels among reunited joiners and resident females. We further predicted that females who face more uncertainty in their social interactions following fusions may use grooming and/or socio-sexual behavior to reduce social tension and aggression. The only aggression on reunion days occurred between reunited females, but frequencies of aggression remained low across non-reunion and reunion days, and there was no effect of fusions on cortisol levels. Fusions did not influence patterns of grooming, but there were increases in socio-sexual solicitations and socio-sexual interactions between joiners and resident females. Joiners who had been separated from residents for longer received the most solicitations, but were also more selective in their acceptance of solicitations and preferred to have socio-sexual interactions with higher-ranking residents. Our results suggest that socio-sexual interactions play a role in reintegrating female bonobos into social groups following fusions. In addition, females who receive a high number of solicitations are able to gain more control over their socio-sexual interactions and may use socio-sexual interactions for other purposes, such as to enhance their social standing.     

Mounting behavior of female guinea pigs after prenatal and adult administration of the propionates of testosterone, dihydrotestosterone, and androstanediol.

Female guinea pigs were exposed prenatally (Day 28–58) to the propionates of testosterone (TP), dihydrotestosterone (DHTP), or androstanediol (ADP). Only TP females failed to display lordosis in adulthood after estrogen and progesterone treatment. When given TP in adulthood, females in all groups mounted, but TP and DHTP females showed augmented intromission frequencies and higher percentages of correctly oriented mounts relative to controls. Moreover, TP females responded more quickly to TP injections in adulthood and had higher over-all mounting frequencies than other groups, while DHTP females displayed mounting frequencies intermediate to controls and TP females. ADP females were not different from controls for any measure of mounting behavior.No female in any group mounted when given DHTP in adulthood, even after 7 wk of daily injections. Since male guinea pigs do mount in response to DHTP given in adulthood, the results raise the possibility that mechanisms determining sensitivity to specific steroids may not be mediated exclusively by steroids during critical periods of embryological differentiation.     

A Juvenile Hormone analogue enhances homosexual behaviour in female‐deprived males of the migratory locust

In laboratory colonies of crowded migratory locusts Locusta migratoria (L.), homosexual behaviour (i.e. males mounting other males) is commonly observed. Female‐deprived males of Locusta migratoria migratorioides R. & F. mount each other in a characteristic mating position, often forming a group of several insects. When allatectomized males are placed together with intact, female‐deprived males, the former are usually mounted by the latter, demonstrating some degree of control involving the corpora allata over homosexual behaviour. This may be related to the positive effects of Juvenile Hormone (JH) or Juvenile Hormone analogues (JHAs) in enhancing male sexual behaviour, as is shown in some other insects. In the present study, a potent JHA (i.e. pyriproxyfen) is injected into a group of young, crowded L. m. migratorioides males, and an equivalent group of control males is maintained in a separate cage. Both groups are deprived of females. Three times a week, during 2‐h observation periods, JHA‐injected and control males are placed together in the absence of females, and homosexual mountings, per group and per individual, are recorded every 10 min. Observations are performed for 10 weeks. Analysis of these data, including the time spent in mounting behaviour, the percentage of individuals within a group involved in the behaviour during the observation periods and the identity of both partners, reveals that the JHA‐treated males show a more intense homosexual mating behaviour than control males in all quantified parameters. This is the first report of the enhancement of homosexual behaviour by an endocrine factor in insects.     

Male dominance status,female choice and mating success in the brown lemming, Lemmus trimucronatus

The objective of this study was to determine whether female brown lemmings would selectively mate with dominant conspecific males. In dyadic encounters, oestrous females paired with dominant males engaged in more frequent lordosis and contact social behaviours than those paired with subordinate males. However, the mount and thrust scores of dominant and subordinate males did not differ significantly. When females had simultaneous access to tethered dominant and subordinate males, they spent more time in close proximity to dominant males and avoided contact with subordinate males. Copulation scores were higher with dominant males. In triadic encounters with free-moving dominant and subordinate males, oestrous females spent more time near, and engaged in more sexual behaviour with, dominant males. Intermale agonistic interactions resulted in ‘privileged access’ to females by dominant males. Sexual behaviour scores were lower and there was a 10-fold increase in intermale aggression in triadic encounters between females and unfamiliar dominant and subordinate males. Both intermale agonistic interactions and female ‘choice’ behaviour accounted for the differential copulatory success of dominant males.     

Social relationships between adult male and female rhesus macaques: 1. Sexual consortships

The sexual relationships of 15 adult male rhesus macaques (Macaca mulatta), of one social group in the Cayo Santiago colony, Puerto Rico, were studied during the 1981 mating season. Two criteria were used to determine whether or not a focal male was in consort in a given 20-min observational sample. One hundred and thirty-two consortships were recorded. The distribution and duration of all consortships, and the distribution of those consortships that coincided with the estimated time of conception, were positively correlated with male dominance rank and length of tenure. Correlations with dominance were stronger than those with tenure. Older females had more consortships with focal males than younger females. There was no relationship between female rank and the distribution of consortships. Consortships did not give exclusive access to receptive females although they may do in feral situations. Males were primarily responsible for maintaining proximity in about two thirds of consortships. The four top-ranking males were primarily responsible in all but one of their consortships. Almost all of those in which the female was primarily responsible involved younger, slightly lower-ranking males. This pattern may have resulted from the females being attracted to the latter males although other interpretations are possible. The partner who was primarily responsible for maintaining proximity also tended to be the predominant groomer, supporting the view that grooming plays a role in the maintenance of sexual consortships. Almost a third of consortships were with females who had conceived, suggesting that males could not accurately assess female reproductive state. Consortships maintained by the male were longer than those maintained by the female. Males may try to increase their chances of fertilising a female by prolonging the consortship. High-ranking males may have been more successful at this, resulting in the positive correlation between male dominance rank and consortship duration.     

Sociosexual behavior of captive sichuan golden monkeys (Rhinopithecus roxellana)

The Sichuan golden snub-nosed monkey, Rhinopithecus roxellana, is an endangered Colobine endemic to China. The social and reproductive behavior of this species are little known, and it has rarely been kept in captivity outside China. Results from observations of a captive golden monkey pair revealed some unusual details of sociosexual behavior. Both members of the pair mounted one other, and female mounting of the male occurred nearly as often as the reverse. Male mounts were always preceded by a stereotyped behavioral sequence that included distinct facial and vocal displays. Female mounts occurred in response to male solicitation (presenting). No evidence of ejaculation was observed in association with mounts, although mounts were only observed in a distinctly sexual context. Sexual behavior was associated with aggressive displays by one or both animals and with apparently proceptive behavior by the female. All sexual behaviors showed a peak near the end of the study, although the female was continually receptive throughout the 2-month study period.     

野生川金丝猴一个全雄青年猴群的同性爬背行为

本研究采用行为取样方法,首次对秦岭野生川金丝猴全雄青年群中的同性爬跨行为进行报道。研究中我们共观察到21 次同性爬背行为,其平均持续时间为5.53 ± 3.11s;雄性同性爬背发生前的行为中以玩耍行为(47.62% )和3 种不同姿势的邀配模仿行为(42.85% )为主;而同性爬背行为发生后则主要为彼此间的相互理毛行为(47.62% )和玩耍行为(23.81% )。对比先前婴幼猴时期的相关研究结果,青年猴同性爬背行为前邀配模仿资势的多样化在一定程度上体现了野生状态下雄性川金丝猴个体青少年阶段的性行为发育进程。考虑到川金丝猴全雄群的社会结构,青年猴同性爬背行为具有巩固社群稳定和加强个体关系的功能。此外,研究中观察到76.19% 的同性爬背行为发生在昼间休息期之后的第一个小时内,这可能是“睡眠与觉醒循环”对性激素的反调节作用所致。     

Effects of Environmental and Social Conditions on Homosexual Pairing in the Japanese Beetle (Popillia japonica Newman)

Homosexual pairing between males occurs under natural conditions in a wide variety of taxa, including many insect species, but few studies have investigated how environmental and social conditions affect same-sex pairing in insects. We investigated factors affecting homosexual pairing in male Japanese beetles (Popillia japonica Newman) in the field and in the laboratory. Specifically, we investigated how time of day, sex ratio, beetle density, and temperature affected the likelihood of homosexual pairing. In the field, male–male pairs constituted 1–6% of the pairs we collected. Homosexual pairs were more common in the afternoon than in the morning and the evening. Sex ratio, density, and temperature were all related to the likelihood of finding a homosexual pair, but the relationships were not linear. In the laboratory, higher male densities and relatively male-biased sex ratios were associated with an increase in the frequency of homosexual pairs. Homosexual pairs were more frequent at relatively low and relatively high temperatures. Males that mounted other males tended to be smaller than the males that they mounted. In addition, compared to males that were not homosexually paired, there was some indication that the mounting males were smaller, and the mounted males larger, than the unpaired males. Our data suggest that homosexual pairs are a result of males mistaking other males for females, and we hypothesize that the environmental and social factors cause changes in homosexual pairing through their effects on the frequency of pair formation and pair duration.