Female reproductive parameters and fruit availability: factors determining onset of estrus in Japanese macaques

This study examined the onset of estrus, nutritional conditions during the mating season, and female reproductive parameters in a troop of unprovisioned Japanese macaques (Macaca fuscata fuscata). The mean interbirth interval (IBI) was 25.1 mo, suggesting a 2-yr birth cycle. The mean IBI following the death of an infant before the mating season was only 19.8 mo, whereas the mean IBI was 27.8 mo when the infant survived. Estrus occurred during the time of the greatest food quality, in the autumn (i.e., mating season). A female whose infant did not survive the mating season tended to come into estrus more readily than one with a surviving infant. Only one of the 19 females whose infants survived came into estrus, whereas 43 of the 58 (74.1%) females whose infants did not survive came into estrus. Fruit conditions during the mating season each year were evaluated by the seed crop of the two species (Fagus crenata and Zelkova serrata) that constituted the main food source for the macaques; fruiting levels were classified as "high-fruit" or "low-fruit." Females came into estrus more often during high-fruit mating seasons than during low-fruit mating seasons: 36 (97.3%) of 37 females came into estrus during high-fruit mating seasons, whereas eight (20%) of 40 females came into estrus during low-fruit mating seasons. Although females came into estrus under both high- and low-fruit conditions during the mating season, estrus seldom occurred when females had a surviving infant, and it appears that the absence of a surviving infant is an almost essential variable for the onset of estrus. When females with a surviving infant were excluded from the analysis because they were unlikely to come into estrus, all 35 remaining females (100%) came into estrus during high-fruit mating seasons, whereas only eight (34.8%) of 23 females came into estrus during low-fruit mating seasons. Therefore, the onset of estrus is strongly affected not only by the survival of infants through the mating season, but also by fruiting conditions, especially the availability of high-quality food.     

Time, gender, and seasonality in vervet activity: A chronobiological approach

A chronobiological approach has been used to highlight the issue of how climatic factors and breeding seasonality may affect male and female diurnal activity budget. We investigated gender differences for vervet monkeys in the diurnal distribution of feeding, locomotion, inactivity, and social grooming within and between birth, pre-mating, and mating seasons. The main climatic traits were that days were shorter, drier, and cooler in the mating season. Non-parametric statistics showed that female activities changed with time of day to a greater extent than did male activities. When the constraints imposed by climatic factors and mate competition increased, from the birth to the mating season, male maintenance activities were more independent of the time of day whereas females continued to vary. Gender differences in timing were therefore greater in the mating season, except for social grooming; males and females were more coordinated in diurnal timing of their grooming in the mating season. It is argued that these changes may result in reduced levels of male-female contest competition, and may be related to higher levels of male-female socialization in the mating season. Finally, it is inferred that an out-of-phase synchronization between inactivity and feeding for males in the birth season, and for females in the mating season, may result from each sex investing more time feeding at the expense of resting in those periods.     

Seasonal, sex, and interspecific differences in activity time budgets and diets of patas monkeys (Erythrocebus patas) and tantalus monkeys (Cercopithecus aethiops tantalus), living sympatrically in northern Cameroon

I examined seasonal, sex, and interspecific differences in activity time budgest and diets of patas (Erythrocebus patas) and sympatric tantalus monkeys (Cercopithecus aethiops tantalus) on the basis of 5-day data sets collected in three and two different seasons, respectively, by the method of focal animal sampling. The seasons included species-specific mating and birth seasons. As compared with not only the birth season but also conspecific females, both patas resident male and tantalus male spent less time feeding and more time resting, day and night, in their respective mating seasons. Given that day-resting time includes time for vigilance for non-resident males and receptive females, this may reflect that males should minimize time spent feeding to allow maximum participation in other fitness-increasing activities such as mating-relating activities asSchoener (1971) predicted. In both species, the males consumed fruits containing less protein but more calories and showed a high feeding rate to compensate for the shorter time spent feeding in the mating season. In contrast, females consumed protein-rich food types (i.e. animals, protein-rich seeds, leaves, and flowers) in the birth season to meet the high demand for protein due to pregnancy and lactation. Given that the season for males was considered to be not a calendar but a reproductive “season” (i.e. mating or birth season), both sexes of patas spent more time moving and less time day- and night-resting than did the tantalus counterparts irrespective of the “season”. Patas subsisted on fruits, gums, and supplementarily lipid-rich seeds as an energy source and animal matters and protein-rich seeds as a protein source. In contrast, tantalus subsisted on fruits and lipid-rich seeds as energy and flowers and leaves as protein.     

Strong temporal consistency in the individual foraging behaviour of Imperial Shags Phalacrocorax atriceps

Individual consistency in foraging behaviour can generate behavioural variability within populations and may, ultimately, lead to species diversification. However, individual‐based long‐term behavioural studies are particularly scarce in seabird species. Between 2008 and 2011, breeding Imperial Shags Phalacrocorax atriceps at the Punta León colony, Argentina, were tracked with GPS devices to evaluate behavioural consistency during their foraging trips. Within a breeding season, individuals were highly consistent in the maximum distances they reached from the shore and the colony, as well as in the time invested in flight and diving across consecutive days during early chick rearing. In addition, each individual had its specific foraging area distinct from the foraging area of other individuals. Comparing between early and late chick rearing in the same season, individuals were consistent, to a lesser degree, in the maximum distance they reached from the colony and the shore, increasing in consistency later on in the season. Within the season, females were more consistent than males in the maximum distance they moved from the colony and the shore, the sexes segregated in their foraging areas and individual females were segregated from one another. Twenty‐eight individuals tracked in different breeding seasons were marginally consistent in their trip durations and maximum distance reached from shore across seasons. Among seasons, foraging locations differed between sexes and among individual females. Individuals from this colony exhibited consistency over time in several aspects of foraging behaviour, which may be due to a combination of individual characteristics such as learning abilities, breeding experience or health, as well as targeted prey type and stability of the environment at this location.     

Non-reproductive copulation behavior among Tibetan macaques (<Emphasis Type="Italic">Macaca thibetana</Emphasis>) at Huangshan,China

Non-reproductive copulation, which takes place outside of the mating season and does not result in conception and birth, was studied in a free-ranging group of Tibetan monkeys (Macaca thibetana) at Mt. Huangshan, China, in the birth seasons of 1992 and 1997. We employed all occurrence and focal animal samplings to record sexual and related behaviors and affiliation interactions, respectively. Compared with sexual behavior in mating season, non-reproductive copulation occurred at a lower frequency, with less frequent ejaculation, less harassment, shorter mount duration, and an absence of pause with vocalization. It often took place in a situation in which non-lactating females were involved in social conflict or approached males for mating. Neither pregnant nor lactating females were observed to mate in the birth seasons. Copulation during the birth season did not increase a sexually receptive female’s delivery the next year, nor was it associated with increased proximity, grooming, or agonistic aid for the mating pair. However, copulated pairs spent more time co-feeding, presumably reflecting an increased tolerance on the part of the male. Adolescent males, who rarely copulated in the mating season, engaged in mating activity in birth seasons as well. Therefore, though birth-season copulation had no reproductive functions, it may have fulfilled social functions for females, such as post-aggression appeasing by males or gaining access to resources. This also offered good opportunities for adolescent males and females to develop their sexual skills for later competition.     

Body composition, age and fertility among free-ranging female rhesus macaques (Macaca mulatta)

The relationship of morphometric measures and birth status among 93 females on Cayo Santiago trapped during the 2001 and 2002 seasons was assessed. The proportion of females giving birth differed between the two seasons (0.58 vs. 0.38; P = 0.006) with a prominent decline among older females. Most morphometric measures increased from adolescent to adult groups, but bicep circumference showed a significant decrease among adults. When controlled for age differences, females with infants during the 2002 season exhibited greater bicep circumference, but no difference in abdominal fat than those without. Members of the socially dominant group did not have a higher rate of birth in either 2001 or 2002, despite being significantly longer and weighing more than those of the subordinate group. Abdominal skinfold and bicep circumference were significant predictors of birth status during the 2002 season, controlling for age group, social group membership, and parity in the previous year. Bicep circumference was also a significant predictor of birth status for the 2001 birth season. These findings suggest that individual variation in body composition among females of Cayo Santiago is associated with differences in fertility.     

黄山短尾猴繁殖的季节性和雌性性活动方式

1987年开始,我们对中国黄山的短尾猴(Macaca thibetana)的性和繁殖行为进行了研究。本文根据1992年全年野外观察,对黄山短尾猴的繁殖季节性和雌性性活动方式进行深入研究,以揭示短尾猴繁殖方式和雌性性行为如何影响雄性性行为。研究采用全事件取样和目标动物取样法。结果表明,短尾猴黄山种群的交配和产仔是季节性的：交配季节发生在7月至12月,其特征是交配频率高并伴有射精;产仔季节为1月至4月。交配季节之外的交配虽有少量发生．但交配频率很低且几乎不射精。成年雌性的会阴部有轻微肿胀的性皮,但性皮的大小和颜色既不随猴群繁殖季节变化,也不随雌性个体生理周期变化。同时,雌性缺乏典型的性要求的行为——发情。因此,我们认为雌性短尾猴倾向于隐蔽自己的排卵。对46个连续观察日中成年雄性对雌性的性行为分析还表明：雄性能够区别潜在繁殖和不繁殖的雌性但不能对同一雌性的生理状况做出准确判断。隐蔽排卵是雌性在性接受期间接受大量交配的主要原因。本研究否定了短尾猴的交配是非季节性的假设(Wadaand Xicmg,1996)[动物学报51(3)：365—375,2005]。     

Male aggression and the sexual behavior of Japanese monkeys

The factors that regulate male aggressive behavior towards females during the mating season and their relationship to the sexual behavior of Japanese monkeys were investigated. Observations were made on the Shiga A troop in Nagano Prefecture for 132 days during both the non-mating and mating seasons in three successive years. As a result, chasing towards females was observed in males older than 4 years. The frequencies of this type of behavior increased in the mating season. The chasing rank of the individual males did not correlate with the male dominance rank but with the tree-shaking rank. Chasing was directed not only at estrous females but also at non-estrous females. Pairs of both sexes in which chasing was observed, tended to have sexual interactions. Both hormonal and social factors should be considered in the regulation of chasing. The role of aggression in the formation of new male-female bonds in discussed.     

Foraging energetics in patas monkeys (Erythrocebus patas) and tantalus monkeys (Cercopithecus aethiops tantalus): implications for reproductive seasonality

The patas monkeys (Erythrocebus patas) in Kala Maloue, Cameroon, have their birth season in the mid-dry season, whereas closely related, sympatric tantalus monkeys (Cercopithecus aethiops tantalus) have their birth season in the wet season. To evaluate the optimality of a species-specific birth season, I estimated the daily intake of available energy and gross protein, and energy expenditure for one individual of each sex of each species between respective birth and mating seasons. The monkeys obtained a larger amount of available energy and gross protein in the birth season than in the mating season. No significant seasonal differences in energy expenditure between the birth and mating season were found. Thus, the birth season appears to be timed to the season when the monkeys can obtain more surplus energy and protein. Interspecific differences in the optimality of birth season were attributed to widely exploitative foraging, supported by the patas' high locomotive ability, which may enable them to obtain more energy from seeds of Acacia seyal and gums of A. sieberiana, and more protein from grasshoppers and seeds of A. seyal in the mid-dry season than the tantalus monkeys. A review of preceding studies suggests that the availability of seeds of Acacia fruiting during the dry season may exert the dominant influence on timing of birth not only in patas but also in savanna monkeys (Cercopithecus aethiops), which include the tantalus monkeys.     

Vagabond males and sedentary females: spatial ecology and mating system of the speckled rattlesnake (Crotalus mitchellii)

We used radiotelemetric data and behavioural observations to characterize seasonal (mating versus post‐mating seasons) and sexual variation in movement patterns, as well as to examine some of the ecological factors contributing to the evolution of the mating system in a venomous predator from the Mojave Desert of North America, the speckled rattlesnake, Crotalus mitchellii. Mating occurs in spring from late April to early June, shortly after emergence from hibernation, when snakes are predictably aggregated around the dens. Males and females travelled further per unit time in the mating season compared to the post‐mating season. Males also travelled longer distances per unit time than females in the mating and post‐mating seasons, and males with larger home ranges during the mating season had more potential mating partners. The results obtained suggest that males actively locate females during the mating season, and that the drastic increase in distance travelled by males during the mating season may be caused by strong male–male competition for access to females, probably because of the limited availability of sexually receptive females. Furthermore, males fight for access to females, and males of larger size are more likely to acquire females. Therefore, sexual selection apparently acts on two different male phenotypic traits: investment in mate‐searching activities and male body size. The present study demonstrates that combining quantitative spatial analyses and behavioural observations in an explicit temporal context can significantly advance our understanding of the ecology and evolution of organismal mating systems. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103 , 681–695.     

Fertility of beef cattle females with mating stimuli around insemination

An experiment was conducted to test the hypothesis that sterile mounts around insemination improves pregnancy rate to artificial insemination (AI) and to define the effects of age, season, time to complete AI and time of day of insemination. A total of 178 Simbrah females were randomly assigned by calving date and body condition to one of three treatments during two consecutive years: (1) mating stimuli with a sterile bull at the time the cows were detected in estrus; (2) mating stimuli immediately after completing AI; (3) without mating stimuli. All cows and heifers were maintained under the same conditions of handling and feeding within the two breeding seasons (winter 1995 and summer 1996). Vasectomized bulls were used for the sterile mounts. Cows and heifers that were given a sterile mount at the time of detection of estrus, had an increased pregnancy rate (60.0%) compared with females given a sterile mount after completing AI (25.4%) or females without the sterile mount (35.6%) (P < 0.01). Age, season, time to complete AI and time of day of AI were all non-significant (P > 0.05). Therefore, there is a biostimulatory effect of mating at the time beef cattle females are detected in estrus, on pregnancy rates to AI.     

Seasonal and diel movement patterns of brown bears in a population in southeastern Europe

Most animals concentrate their movement into certain hours of the day depending on drivers such as photoperiod, ambient temperature, inter‐ or intraspecific competition, and predation risk. The main activity periods of many mammal species, especially in human‐dominated landscapes, are commonly set at dusk, dawn, and during nighttime hours. Large carnivores, such as brown bears, often display great flexibility in diel movement patterns throughout their range, and even within populations, striking between individual differences in movement have been demonstrated. Here, we evaluated how seasonality and reproductive class affected diel movement patterns of brown bears of the Dinaric‐Pindos and Carpathian bear populations in Serbia. We analyzed the movement distances and general probability of movement of 13 brown bears (8 males and 5 females) equipped with GPS collars and monitored over 1–3 years. Our analyses revealed that movement distances and probability of bear movement differed between seasons (mating versus hyperphagia) and reproductive classes. Adult males, solitary females, and subadult males showed a crepuscular movement pattern. Compared with other reproductive classes, females with offspring were moving significantly less during crepuscular hours and during the night, particularly during the mating season, suggesting temporal niche partitioning among different reproductive classes. Adult males, solitary females, and in particular subadult males traveled greater hourly distances during the mating season in May‐June than the hyperphagia in July–October. Subadult males significantly decreased their movement from the mating season to hyperphagia, whereas females with offspring exhibited an opposite pattern with almost doubling their movement from the mating to hyperphagia season. Our results provide insights into how seasonality and reproductive class drive intrapopulation differences in movement distances and probability of movement in a recovering, to date little studied, brown bear population in southeastern Europe.     

Scratching around mating: factors affecting anxiety in wild Lemur catta

Scratching has been successfully used to detect anxiety, a proxy for stress, in primates, from strepsirrhines to Homo sapiens. Here, we investigated the fluctuation of scratching in Lemur catta during the mating season. In particular we evaluated whether scratching (1) varied according to sex and rank differences, (2) increased in the period of maximum stress (around the mating days), and (3) was reduced by grooming. At Berenty (South Madagascar), we followed two lemur groups (23 adult/subadult individuals) and gathered data on self-scratching, aggression, and grooming. Based on perineal area features, we recognized two periods: low swelling (LS), with no estrus female, and high swelling (HS), when at least one female was in estrus. We predicted that aggressive behaviors and anxiety-related scratching would covary. Indeed, scratching peaked in HS, when aggression was also highest. In agreement with previous literature, this result suggests that conflicts around estrus days may raise anxiety levels in the social group. We expected scratching levels to be highest in males because they aggressively compete for females and are subject to mate choice and repeated attacks by dominant females. Instead, the scratching rates were similar in males and females, probably because the high competition, which involves both sexes, dampened intersexual differences. In contrast to our prediction, scratching was not rank dependent, probably because animal ranking positions changed from LS to HS. Finally, we showed that, in ring-tailed lemurs, as well as in other primates, scratching decreases after reciprocal grooming in both periods. This finding provides the first evidence that grooming could assist in reducing anxiety in strepsirrhines.     

Evidence for seasonal variation in aggressive behaviour by Macaca mulatta

Observations were made on the Macaca mulatta colony on the island of Cayo Santiago over a period that included two reproductive cycles. The frequency of aggressive behaviour was found to fluctuate cyclically as a function of the colony's reproductive state. Males were wounded and died significantly more frequently during the mating season than at any other time of year. Females were wounded about as often during the mating season as during the birth season, and more died during the birth season than during the mating season, although not significantly so. There was no significant difference between sexes in age at death, nor was there a significant departure from expectation of number of deaths per age class. However, mortality among the reproductively mature males was greater than among mature females. It was suggested that differential injury and mortality rates among adult males might be an indirect result of high levels of androgens which could conceivably alter threshold levels for stimuli initiating severe aggressive interactions.     

Two spawning seasons and mating system of the bastard halibut, Tarphops oligolepis

We investigated the breeding habits of the bastard halibut, Tarphops oligolepis, in the southwest of Kyushu Island, Japan. This fish was found to have two spawning seasons in a year (around July and November); individual fish spawned over the two spawning seasons. During the spawning seasons, males established territories. Home ranges of females overlapped with those of other females and with territories of plural males. The courtship partner changed during a day, and multiple matings among both sexes were observed during a spawning season, suggesting that T. oligolepis bred promiscuously. This is the first report of the mating system among Paralichthyidae. Received: October 18, 2000 / Revised: May 7, 2001 / Accepted: July 9, 2001     

Social relationships between adult male and female rhesus macaques: II. non-sexual affiliative behaviour

The social relationships of adult male rhesus macaques (Macaca mulatta) in Group I of the Cayo Santiago colony were studied over a period of 14 months. Relationships were found in which adult males and sexually mature females were persistently close to one another in nonsexual contexts, both within and across seasons. Males of long tenure and high dominance rank tended to have more female partners, and more persistent relationships, than more recent immigrants of lower rank. Correlations with length of tenure were stronger than those with dominance rank. Closely-related females tended to have persistent relationships with the same male. In most cases the female was primarily responsible for maintaining proximity in non-sexual contexts. Dyads which were persistently within 5 m of each other in the birth season were more likely to form a consortship in the subsequent mating season than those which had a brief relationship. A similar tendency was apparent in the 1 m data but it was not statistically significant. There was no association between persistent proximity during the birth season and the occurrence of long, or multiple consortships, nor with the maintenance of proximity or direction of grooming between consort partners. The pattern of consortships was not closely related to the formation of persistent relationships in the subsequent birth season. Females occasionally received protection from their male partners and, in some cases, spent more time in the feeding corral with them than did other females. Affiliative relationships can be very enduring and may have long-term benefits that were not apparent during the study period.     

Timing of parturition in the rat: an analysis of successive births

To determine whether consecutive parturitions within individual rats are likely to occur around the same time of the 24h day, female rats mated prior to ovulation and maintained on a LD 12:12 photoperiod, were observed over either two or three parturitions. A subgroup of females was placed on constant light during the second gestation in order to determine the role of photoperiod in the temporal synchronization of consecutive births. The major findings were 1. individual females tended to give birth around the same time of the day on consecutive births so long as the photoperiod remained constant; 2. the small percentage of births occurring during darkness, the less-prevalent time of the photoperiod for birthing, were anomalous births for individual females; and 3. litter weight was a significant factor in predicting time of birth for females, but this effect interacted with photoperiod. These data elucidate the importance of knowing previous birth time, litter weight, and photoperiod on predicting the time of parturition in the rat.     

The effect of pregnant and oestrous females on male testosterone and behaviour in the tammar wallaby

Tammar wallaby females (Macropus eugenii) are seasonally breeding marsupials with a post-partum oestrus after a highly synchronised birth period when testosterone concentrations rise in males. Chemical communication appears to be important for mating, as males show checking behaviour, sniffing the urogenital opening (UGO) and the pouch of females. This study investigates whether the presence of pregnant and oestrous females directly influences testosterone in males and if oestrous odours or secretion from the pouch or UGO are attractive. Concentrations of plasma testosterone were measured in males housed with pregnant and oestrous females during two consecutive cycles in the breeding season, and an artificially induced cycle in the non-breeding season. Males were also tested for their interest in swabs taken from the urogenital opening (UGO) or pouch of oestrous females. Testosterone increased sharply in males in the presence of pregnant and oestrous females during all cycles in both seasons, but there was no change when males were exposed to non-cycling females in lactational or seasonal diapause. Males had no preference for either oestrous or non-oestrous samples taken from the pouch or from the UGO from oestrous females. This study confirms that the increase in plasma testosterone in tammar males can be induced through the presence of pregnant and oestrous females, regardless of season and that the increase began when the females were in late-pregnancy. This confirms that the male's reproductive state is dependent on a signal from females and is not blocked through seasonal effects.     

Triadic Positions of Tibetan Macaques Huddling at a Sleeping Site

We studied huddling of Tibetan macaques (Macaca thibetana) at a sleeping site in Huangshan, China, during the mating and birth seasons. Tibetan macaques in a free-ranging group made physical contact with each other and formed huddling groups on the ledge of a steep cliff at night. We analyzed the size and composition of huddling groups and the frequencies of dyadic huddles—two individuals in physical contact—in the huddling group to determine the social influences on huddling behavior. Affiliated dyads that frequently groomed in the daytime frequently formed dyadic huddles in night-time huddling groups. Female–male dyads formed dyadic huddles less frequently than expected. In addition, Tibetan macaques chose 2 partners with which they initiated contact when they approached a huddling group. The frequencies with which some combinations of 3 individuals contacted each other and formed triangular huddles are not consistent with the expected frequencies. For example, female–male–male triads frequently formed triangular huddles in the birth season but did so infrequently in the mating season because of male competition for estrous females. When all 3 dyads within a certain triad formed dyadic huddles frequently, the triad was more likely to form a triangular huddle. The choices of approaching individuals might make a systematic, rather than random, positioning of individuals in huddling groups at their sleeping site.     

Individual Quality and Extra-Pair Paternity in the Blue Tit: Sexy Males Bear the Costs

Adaptive explanations for the evolution of extra-pair paternity (EPP) suggest that females seek extra-pair copulations with high quality males. Still, the link between ornamentation, individual quality, and paternity remains unclear. Moreover, honest signaling is essential when explaining EPP because it is needed for sexual selection to occur; yet, it is understudied in multiple ornaments. Because blue tits (Cyanistes caeruleus) show variable color expression in several plumage patches, we tested: (i) over two seasons, whether males in better condition, more ornamented and less infected by blood parasites gain EPP and have higher reproductive success, and (ii) over three seasons, whether mating patterns affect color change. Males with more saturated yellow feathers, brighter tails, and in better condition had higher reproductive success in one of the seasons. Contrary to expectation, in another season, males that gained EPP were parasitized by blood parasites, suggesting increased vector exposure during extra-pair copulations. Our results for two seasons show that males siring more extra-pair young were older and grew brighter cheek or tail feathers for the following season. Despite the increased mating costs, in socially monogamous avian systems, high quality males incur in EPP without compromising traits that may be under sexual selection.