Female Defensibility in a Small Troops of Japanese Macaques vis-à-vis Nontroop Males and Copulation on the Periphery of the Troop

I provide data compiled over 4 yr on the mating behavior in small troops of wild Japanese macaques on Yakushima Island. The key parameters are the number of sexually receptive females, the number of nontroop males (NTMs), and copulation on the periphery of the troop. I analyzed the following aspects: 1) changes in the proportion of copulation with high-ranking males (HRMs) and NTMs, 2) variations in factors such as fluctuation in the number of sexually receptive females and troop males and their effects on the number of visiting NTMs, 3) the effect of attempted interruption of mounting series by other males, and 4) some aspects of copulation on the periphery of the troop. Throughout the study, 56% of the total number of females mated most frequently with the α-male in a single mating season. However, the relative mating success of HRMs varied over the years and between individuals. The number of visiting NTMs varied depending on the number of receptive females and troop males. Females tended to mate with the NTMs when they appeared around their troops. The direct effect of interruption of the mounting series by other males is equivocal. The females mated with the low-ranking males (LRMs) and NTMs on the periphery of the troop, which increased the possibility of mounting series ending with ejaculation. Females actively sought opportunities for copulation on the periphery of the troop by moving there or initiating close proximity with LRMs and NTMs there. On Yakushima Island, the mating success of HRMs was not always as high as that predicted by the priority of access model. The injury status of the HRM, the number of visiting NTMs, and female choice are all considered to influence a male’s mating success.     

Mating behavior ofXylotrechus pyrrhoderus Bates (Coleoptera: Cerambycidae) V. Female mounting behavior

Female mounting behavior was observed in the grape borerXylotrechus pyrrhoderus Bates (Coleoptera: Cerambycidae) under laboratory conditions. This behavior was directed towards either females (i.e., female homosexual mounting) or males. The female homosexual mounting was strongly elicited in females which had previously been allowed to fly. The frequency of this behavior was not related to the experience of mating. The investigation of the daily temporal pattern in female homosexual mounting activity indicated that the behavior most frequently occurred between 12∶00 and 16∶00, i.e., when females were searching for the pheromone-releasing males. Oviposition was also observed during this time interval. A detailed analysis revealed female mounting behaviors which are characteristic of male mounting behaviors, such as chasing conspecifics and synchronism of licking and abdominal bending. On the other hand, the frequency of male homosexual mounting was lower than that of females. Taken together with cases of other species previously reported, the expression of mounting behavior in females may be related to the evolution of the reproductive system, in which females approach their mates.     

Feeding Competition in <Emphasis Type="Italic">Macaca fascicularis</Emphasis>: An Assessment of the Early Arrival Tactic

In primate species with unidirectional dominance relationships, rank order restricts the access of nondominant females to clumped resources. However, females might attempt to bypass the rank order by reaching feeding sites before the highest ranking individuals (early arrival tactic) when there are net benefits. We therefore analyzed the order of arrival to the feeding site of the adult members of a captive group of long-tailed macaques. We used 2 experimental conditions that differed in the spatial distribution of a fixed amount of food (large vs. small patch). Though each condition induced contest competition, it was stronger in the small-patch condition. Arrival order does not correlate with dominance rank in either experimental condition. The α-male and α-female reached the feeding site 10–30 s after the beginning of the test. Some females seized on opportunities to reach the feeding site before them, especially in the large-patch condition. They used the early arrival tactic when the risks of aggression were relatively low, which subjects accomplished either by being dominant or by being nondominant but tolerated by the α-male. Social tolerance may provide individuals with an alternative means to obtain resources. In sum, variation in food abundance and distribution may affect the extent to which rank order determines order of arrival to feeding sites. A higher rank may confer priority in the choice of tactics, but not necessarily priority of access to the resources themselves.     

Intensive resistance by females before copulation induces insemination failure in the West Indian sweet potato weevil <Emphasis Type="Italic">Euscepes postfasciatus</Emphasis>

Persistent mating attempts by males (sexual harassment) are frequently observed among animals. For females, resisting persistent males can be costly because vigorous resistance increases both energy expenditure and the possibility of injury. Although one tactic for coping with male harassment is to cease resistance and mate with the persistent partner, the females of several species are able to prevent the fertilization of their egg(s) despite copulation. In this study, we used three different sex ratios to investigate whether a male’s mating persistence affects his mating success in the West Indian sweet potato weevil Euscepes postfasciatus, in which males mount females both before and after copulation. Consistent with our predictions, we found that female weevils resist and manipulate sperm transfer either before or during copulation according to their preferences. Female weevils were able to reject the sperm of persistent males despite having copulated with them. However, neither copulation and/or post-copulatory mounting affected insemination success. We speculate that the intensive resistance shown by females before copulation may induce mechanical sterility in E. postfasciatus.     

Hierarchy,kinship and social interaction among Japanese monkeys (Macaca fuscata)

The study reports the relationship between hierarchy, genetic relatedness and social interaction in captive Japanese macaques. Grooming and proximity were found to be positively related to both dominance rank and degrees of relatedness. Ranks also positively correlated with threats while no relationship was observed between genetic relationships and agonistic interactions. The removal of a-male tightened the male hierarchy while the female hierarchy became relatively loose. Affiliative behaviour became more correlated with ranks than degrees of genetic relatedness. In the absence of α-male, the next dominant male avoided involvement in either agonistic or afliliative interactions with reintroduced animals and group females.     

Intrasexual mounting in the beetle Diaprepes abbreviatus (L.).

The weevil Diaprepes abbreviatus shows three kinds of same-sex mountings: males mount other unpaired males, males mount males already engaged in copulation and females mount other females. Four hypotheses were evaluated in order to explain same-sex matings by males: (i) female mimicry by inferior males, (ii) dominance of larger males which affects the behaviour of small males, (iii) sperm transfer in which smaller males gain some reproductive success by 'hitchhiking' their sperm with the sperm of larger males, and (iv) poor sex recognition. Data from mate choice and sperm competition experiments rejected the female mimicry, dominance and sperm transfer hypotheses and supported the poor sex recognition hypothesis. We tested three hypotheses in order to explain female mounting behaviour: (i) females mimic male behaviour in order to reduce sexual harassment by males, (ii) females mount other females in order to appear larger and thereby attract more and larger males for mating, and (iii) female mimicry of males. The results of our mate choice experiments suggested that the female mimicry of males hypothesis best explains the observed female mounting behaviour. This result is also consistent with the poor sex recognition hypothesis which is the most likely explanation for male and female intrasexual mating behaviour in many insect species.     

Female aggregation and male competition reduce costs of sexual harassment in the mosquitofish Gambusia holbrooki

Male mosquitofish allocate a large proportion of their time budget to attempting to inseminate unreceptive females. Because females invest considerable time and energy in avoiding unwanted copulations, sexual harassment is expected to conflict with other activities such as foraging. We found that sexual harassment more than halved the foraging efficiency of the female in a task requiring the retrieval of food items scattered on the water surface. The presence of shoalmates relieved the female from harassment and foraging efficiency increased with the number of females in the group. Small males attempted to mate significantly more than large males, causing a greater reduction in the female's foraging efficiency. When several males competed for the same female, the larger, dominant male prevented all the other males from attempting to mate and so had fewer opportunities to attempt copulation. Harassment from solitary males appeared to be more costly, as females foraged more efficiently when chased by a group of males. Because male sexual activity has a large impact on a female's feeding efficiency and possibly on her survival and reproduction, sexual conflict is expected to be important in shaping association patterns of female mosquitofish with conspecifics of both sexes. Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour      

Influence of host-plant density and male harassment on the distribution of female Euphydryas anicia (Nymphalidae)

Summary We studied behavioral mechanisms underlying the spatial distribution of Euphydryas anicia (Lepidoptera: Nymphalidae) females searching for larval host plants on a flat plain in Colorado. The rate of female movement, as represented by an empirically estimated diffusion coefficient, is affected by two factors. First, when searching in areas of high host-plant density, females tend to make sharper turns and fly for shorter distances between landings, compared to areas of low plant density. As a result, the rate of female displacement is lowered when they search in areas of high host-plant density, and thus females tend to aggregate in such areas. The second factor affecting female movement is the presence of males. Harassment by males induces females to increase the rate of their movement, and females are often chased out of host patches by males. Our results explain the observed spatial and temporal patterns of female distribution in relation to the distribution of host plants and males. In years when host plants are plentiful, harrassement by males in one host patch induces females to move to another. This pattern of female movement tends to disrupt the relationship between the spatial distributions of host plants and females, as well as females and males. In the year when hosts were concentrated in a single large patch, females could not easily avoid male harassment, and consequently we observed strong corelations of female-host distributions and male-female distributions.     

Harassment of Mature Female Chimpanzees by Young Males in the Mahale Mountains

Juvenile and adolescent male chimpanzees sometimes threaten older, apparently stronger individuals such as mature females. I label the behavior harassment. Harassment comprises 25 behaviors, 14 of which are accompanied by the use of objects such as branches: Clubbing, flailing and throwing are the most common. Females respond to harassment with 10 behaviors, including scream, avoid, ignore, and retaliate. Females tend to respond to harassment by juvenile males by ignoring them. However, they are more likely to retaliate, scream or avoid in response to harassment by adolescent males. I propose the rank improvement hypothesis that harassment initiates the process of male domination of females, and compare the predictions derived from it with those of the exploratory aggression hypothesis. Males stopped harassing females significantly earlier when females ignored them versus when they did not ignore them. This is not consistent with the exploratory aggression hypothesis. Males harassed adult females significantly longer when females retaliated than when they did not, which is consistent with the rank improvement hypothesis. Although the observations are congruent with my hypothesis, we need more data to test it.     

Mating patterns,mate choice,and birth season heterosexual relationships in free-ranging rhesus macaques

Birth season adult heterosexual nonkin relationships of 50 free-ranging female rhesus macaques (Macaca mulatta) in two social groups at Cayo Santiago, Puerto Rico were examined using focal follow (289 hr) and ad lib data. Eighty-eight percent of subjects had at least one relationship characterized by particularly high frequencies of spatial proximity, grooming, or both. These were designated “friendships.” Males intervened in aggressive interactions more frequently on behalf of Friends than non-Friends. Female aggressive support of males was extremely rare. Higher-ranking males experienced more friendships than lower-ranking males. High-ranking females had higher-ranking Friends than low-ranking females. Older females had higher-ranking Friends than younger females. Females groomed high-ranking Friends more than they were groomed by them, whereas they groomed low-ranking Friends less than they were groomed by them. In one social group, high-ranking females were more likely than low-ranking females to groom their Friends more than they were groomed by them. Males were more responsible than females for spatial proximity maintenance in 9 of 14 Friend dyads for which sufficient data were available. Neither male nor female dominance rank affected responsibility for proximity maintenance in Friend dyads. Eight of 24 females had friendships with males with whom they had completed copulations during their conception peri-ovulatory period of the preceding mating season. Two of 19 females completed peri-ovulatory copulations with Friends during the following mating season. Friendship was not correlated with either of two demonstrated female mate choice indicators: (1) proximity maintenance during estrus; or (2) cooperation with male “hip-grasp” courtship attempts. Males directed “muzzle-up” courtship signals at lower rates toward Friends than toward non-Friends. These and other investigators' results indicate that (1) protection from aggression is the primary benefit to female rhesus macaques of birth season heterosexual relationships; (2) the most effective protectors are in greatest demand as Friends; and (3) friendship has no effect or an inhibitory effect on mate choice in this species. Benefits to males of friendships were not apparent from this study but may include coalitional support against lower-ranking males.     

Intergroup calls of male pig-tailed langurs (Simias concolor)

Pig-tailed langurs (Simias concolor) were observed in the Pagai Islands and in Siberut. They lived in 1-male groups containing from one to five or more females plus their young. Adult males produced loud vocalizations of the sortGautier andGautier (1977) called “type 1 loud calls.” The pig-tailed langur's type 1 loud call (TOLC) was a series of 2 to 25 nasal barks, the loudest of which could be heard for 500 m or more in the rain forest. Exchange of TOLC's between males was the only frequent intergroup interaction. Fifty-one percent of TOLC's were emitted spontaneously, 33% occurred in response to TOLC's of other males, 13% to falling trees, 4% in response to thunder, and 1% during a fight between males of different groups. Although TOLC's occurred throughout the day, they exhibited a bimodal distribution, with a peak of calling early in the morning, and another in late afternoon. Tape-recorded TOLC's played back in the field stimulated males hearing them to emit TOLC's of their own. Barks in experimentally-elicited TOLC's were delivered at a faster rate than barks in other TOLC's were. While TOLC's mediate intergroup communication among males, field playback experiments are needed to truly elucidate their functions.     

Pattern, Distribution, and Function of Greeting Behavior Among Black-and-White Colobus

Various species of primates engage in greeting, a ritualized pattern of nonaggressive behavior that usually occurs during a reunion. Black-and-white colobus (Colobus guereza) perform overhead mounting, mounting, and embracing behavior soon after an aggressive act and in nonagonistic situations. We studied the pattern, distribution, and function of the greeting behavior in 2 captive groups of black-and-white colobus. Overhead mounting was the most frequent pattern, accounting for >60% of all greetings (N=333). In nonagonistic situations, younger subordinate individuals greeted an older dominant individual more frequently than vice versa. A dominant male in a small multimale group frequently initiated contacts with adult females, though he was the oldest in the group. Conversely, the dominant male in a large 1-male group never greeted group members. Immediately after performing the greeting, the greeter groomed the recipient in more than half the cases. In the large group, greeting frequency correlates positively with the age difference between the pair; however, there is no correlation between the relatedness, affiliation frequency, or aggression frequency of a pair in either the small or large group. The results are consistent with the hypothesis that greeting behavior functions as a tension-reducing mechanism in nonagonistic situations. There is no evidence, however, that greeting functions to express social status or to attract a mate. In addition, the frequent greeting by the adult male in the small multimale group may indicate that individuals affirm social bonds via greeting behavior.     

Costs and benefits for water strider (Aquarius paludum) females of carrying guarding, reproductive males

We describe the mating system of Aquarius paludum insularis based on field observations and test hypotheses about the effects of body size, hunger level and post-copulatory guarding on reproductive performance. The mating sequence of this species was typical for temperate water striders, except that most oviposition was carried out by tandem pairs, most of which were submerged. Mate guarding continued until the end of oviposition, lasting up to 18.2h, which was much longer than that recorded for other species of water striders. Pair partners changed after oviposition. Extended contact guarding reduced female mobility. In the case of females that carried long-winged males, there was a significant reduction in speed and stride between tandem as opposed to single females. However, when short-winged males were carried, there was not a significant difference. Short-term foraging efficiency did not differ significantly between tandem and single females, and thus did not reflect the difference in mobility. Hunger level did not significantly affect female mating receptivity. Although the number of harassment bouts by unpaired males did not differ between single and tandem females, single females suffered significantly more harassment. Females were able to lay fertilized eggs for about 15 days after a single copulation, but they accepted long guarding and multiple mating during this period as well. The cost of resisting male mating attempts appears to be greater than the cost of carrying males.     

A study on the social structure and dispersal patterns of hamadryas baboons living in a commensal group at Taif,Saudi Arabia

Three levels of hamadryas social structure—the one male unit (OMU), the band, and the troop—have been observed at all sites studied, but a fourth—the clan—has been observed at only one site, Erer-Gota, Ethiopia, during a longitudinal check of the dispersion of identified individuals. The clan is important since it appears to provide the basis for male philopatry, although comparative data is needed from other sites to confirm this. We studied a huge commensal group of hamadryas baboons (over 600 animals) in Saudi Arabia. We put ear tags on baboons between 1998 and 2004 and analyzed social structure, relying on the interactions of these tagged animals by focusing especially on their dispersal patterns from OMUs. OMU membership tended to be looser than that of the Ethiopian hamadryas. Females tended to shift between OMUs on an individual basis in our study group, whereas the collapse of an OMU was a major occasion of adult female transfer in Ethiopia. We found neither stable bands (a “band” in our study group was defined as a regional assemblage of OMUs) nor clans that lasted for several years. Some OMUs moved and transferred into neighboring areas over both the short and long term. Further, some post-adolescent males appeared to move out of the study area. The ratio of adult females in an OMU in our study group was larger than for any other documented study site, and this may be the reason for enhanced female transfer between OMUs. A large proportion of the adolescent females showed no clear membership to OMUs, and no “initial units” (commonly observed in Ethiopia) were discernible. The ease with which young males acquired adult females at the study site must have disrupted the formation of a clan, a “male-bonded society.”     

The effects of male harassment on mating duration in the seed bug,Togo hemipterus

Harassment on mating pairs by solitary males is usually considered an attempt by the male to (1) take over the female, (2) guard the female against further insemination (when the solitary male has previously copulated with this female), or (3) influence mating duration. Paired males of a seed bug repel harassment on mating pairs by solitary males by firmly grasping females using their legs and/or genital claspers; in this way, mating duration is prolonged. Male fertilization success increases as mating duration increases. Males of the seed bug, Togo hemipterus (Scott) (Heteroptera: Lygaeidae), use seminal substances to inhibit female remating. These substances induce protracted female refractory periods and are transferred to the females in a time‐dependent manner. Consequently, mating duration has important effects on fitness in this species. We observed harassment on T. hemipterus mating pairs by solitary males, and examined conflicts between paired and solitary males over mating duration. None of the solitary males were able to take over a mating female, and this may be due to the unique male genital structure in this species. All conflicts over mating duration resulted in wins by the paired males over the solitary males. Paired males prolonged mating durations, whereas severe harassment on mating pairs by solitary males shortened durations. We show that even though there is no immediate reward for the solitary male (i.e., it is unable to take over the mating female), this harassment behavior may be adaptive.     

Mating behaviors of the proboscis monkey (Nasalis larvatus)

The mating behaviors of the proboscis monkey were observed in a riverine forest along a tributary of the Kinabatangan River, Sabah, Malaysia, for a period of 30 months. Solicitation for copulation was initiated frequently by males and occasionally by females. Most copulations involved only one mount; however, some multiple-mount copulations were observed and a maximum of six mounts per copulation were recorded. The mean duration of mounts was about 27 sec. Nonsexual mounts (female-female, female-juvenile/infant, juvenile-juvenile, and juvenile-infant) were also observed. Female-female mounts occurred shortly after failed solicitations toward males were observed. Harassment by juveniles and/or infants was observed during copulation; however, these harassments apparently did not interfere with copulation. Sexual swelling was evident in 77.4% of copulating females, with copulating subadult females showing the most distinct swelling.     

Group Fission in Moor Macaques (Macaca maurus)

This is the first report of group fission in a wild group of Moor macaques (Macaca maurus) in South Sulawesi, Indonesia. The subject group, which has been observed on the basis of individual identification since 1988, showed no sign of fission in April 1999. In August 1999, the group had split in two, with the same number of mature females in each new group. For the most part, mothers and their offspring joined the same groups. Dominance relations and association patterns established during the previous year among adult females did not strongly affect new group membership. The difference in female reproductive state between the two branch groups was a prominent characteristic. The -male of the original group visited both groups at the first stage of group fission, even though otherwise the compositions of the new groups were stable. After the division, six adult males from outside the original group immigrated exclusively into the group that did not contain the -male of the original group. Severe intergroup encounters occurred between the two groups. We discuss the process of the fission and the resultant pattern in relation to the egalitarian dominance style among females, lack of seasonality in reproduction, and resemblance to one-male type social organization.     

The costs and benefits of multiple mating in a mostly monandrous wasp

The taxonomically widespread nature of polyandry remains a puzzle. Much of the empirical work regarding the costs and benefits of multiple mating to females has, for obvious reasons, relied on species that are already highly polyandrous. However, this makes it difficult to separate the processes that maintain the current level of polyandry from the processes that facilitate its expression and initiated its evolution. Here we consider the costs and benefits of polyandry in Nasonia vitripennis, a species of parasitoid wasp that is “mostly monandrous” in the wild, but which evolves polyandry under laboratory culture conditions. In a series of six experiments, we show that females gain a direct fecundity and longevity benefit from mating multiply with virgin males. Conversely, mating multiply with previously mated males actually results in a fecundity cost. Sexual harassment may also represent a significant cost of reproduction. Harassment was, however, only costly during oviposition, resulting in reduced fecundity, longevity, and disrupted sex allocation. Our results show that ecological changes, in our case associated with differences in the local mating structure in the laboratory can alter the costs and benefits of mating and harassment and potentially lead to shifts in mating patterns.     

Variably male-biased sex ratio in a marine bird with females larger than males

When the costs of rearing males and females differ progeny sex ratios are expected to be biased toward the less expensive sex. Blue-footed booby (Sula nebouxii) females are larger and roughly 32% heavier than males, thus presumably more costly to rear. We recorded hatching and fledging sex ratios in 1989, and fledging sex ratios during the next 5 years. In 1989, the sample of 751 chicks showed male bias at hatching (56%) and at fledging (57% at ˜90 days). Fledging sex ratios during the five subsequent reproductive seasons were at unity (1 year) or male-biased, varying from 56% to 70%. Male bias was greater during years when mean sea surface temperature was warmer and food was presumably in short supply. During two warm-water years (only) fledging sex ratio varied with hatching date. Proportions of male fledglings increased with date from 0.48 to 0.73 in 1994, and from 0.33 to 0.79 in 1995. Similar results were obtained when the analysis was repeated using only broods with no nestling mortality, suggesting that the overall increase in the proportion of males over the season was the result of sex ratio adjustments at hatching. The male-biased sex ratio, and the increased male bias during poor breeding conditions supports the idea that daughters may be more costly than sons, and that their relative cost increases in poor conditions. Received: 3 February 1998 / Accepted: 12 September 1998     

Behavioural Consistency in Female Resistance to Male Harassment in a Water Strider Species

Sexual conflict over mating rate often implies that males persist at frequently harassing females to gain matings while females resist mating attempts. In water striders, females can resist by engaging in vigorous pre‐copulatory struggles to dislodge males, but alternative means of resistance have seldom been investigated. Contrary to males, female resistance has not been investigated as a repeatable behaviour. We used Gerris buenoi to investigate the capacity to abbreviate struggles and the tendency to hide off the water as two potential female resistance traits. Specifically, we asked whether these behaviours are repeatable and whether they vary according to sexual conflict intensity and past mating experience. Also, we studied the possible connections between these behaviours and traits linked to fitness, namely endured harassment and mating activity. The capacity to abbreviate struggles was poorly repeatable and decreased with sexual conflict intensity and endured harassment. It seems to be mainly determined by the social environment and by recent events related to sexual conflict. The tendency to hide off the water was significantly repeatable across sexual conflict intensities and can be considered as a repeatable behaviour. Hiding frequently off the water allowed females to decrease the harassment endured by females and may enhance female fitness. In nature, hiding is more readily and more frequently observed than pre‐copulatory struggles. Directly associating hiding off water with female fitness would confirm that this consistent phenotype contributes to sexually antagonistic female resistance.