Sexual and Hormonal Cycles in Geriatric Gorilla gorilla gorilla

As our closest living relatives, great apes likely experience behavioral and physiological patterns associated with reproductive aging and menopause that are similar to human patterns. We present results from a nationwide zoo-based study on behavioral and hormonal changes in female western gorillas. We evaluated progestogen concentrations via daily fecal sampling in 30 gorillas, 22 of which were geriatric (≥30). We collected concurrent behavioral data 1–3 times weekly on 16 of the females. While control females cycled regularly, ca. 23% of geriatric females are acyclic (menopausal), and another 32% show variable hormonal patterns suggesting perimenopause. Patterns included increased variability in cycle length and peak progestogen values, and frequent insufficient increases in progestogen levels during the luteal phase. Acyclic females have significantly lower overall progestogen concentrations than the self cycling females, though differences are not significant when cycle phase is incorporated. We detected behavioral estrus in 9 of 10 cycling females for which data were available. In all but 1 case, proceptive behavior occurred during the follicular phase, preceding ovulation on average by 6.6 d. Females spent more time in proximity to the silverback male while in behavioral estrus than during other periods. To date, maximum longevity in captive female gorillas is 52 yr, with poor reproductive prognosis beginning from the age of 37. We demonstrate that both perimenopause and menopause characterize aged female gorillas, which may experience a postreproductive lifespan of >25% of their lives. Continued study of aging apes is warranted, and apes may serve as models for age-related reproductive changes in humans.     

Litter loss triggers estrus in a nonsocial seasonal breeder

Sexually selected infanticide (SSI) is often presumed to be rare among seasonal breeders, because it would require a near immediate return to estrus after the loss of an entire litter during the mating season. We evaluated changes in reproductive strategies and the reproductive fate of females that experienced litter loss during the mating season in a seasonal breeder with strong evidence for SSI, the brown bear. First, we used a long‐term demographic dataset (1986–2011) to document that a large majority of females (>91%) that lose their entire litter during the mating season in fact do enter estrus, mate, and give birth during the subsequent birthing season. Second, we used high‐resolution movement data (2005–2011) to evaluate how females changed reproductive strategies after losing their entire litter during the mating season. We hypothesized that females would shift from the sedentary lifestyle typical for females with cubs‐of‐the‐year to a roam‐to‐mate behavior typical for receptive females in no more than a few (~3) days after litter loss. We found that females with cubs‐of‐the‐year moved at about 1/3 of the rate and in a less bimodal diurnal pattern than receptive females during the mating season. The probability of litter loss was positively related with movement rate, suggesting that being elusive and sedentary is a strategy to enhance cub survival rather than a relic of cub mobility itself. The movement patterns of receptive females and females after litter loss were indistinguishable within 1–2 days after the litter loss, and we illustrate that SSI can significantly reduce the female interbirth interval (50–85%). Our results suggest that SSI can also be advantageous for males in seasonally breeding mammals. We propose that infanticide as a male reproductive strategy is more prevalent among mammals with reproductive seasonality than observed or reported.     

Seasonality in Reproduction of <Emphasis Type="Italic">Lepilemur edwardsi</Emphasis>

Sportive lemurs are threatened species in the IUCN Red Data Book. However, quantitative information on their reproduction, urgently required for conservation, has been lacking. We collected first data on reproductive activity of Milne-Edwards’ sportive lemurs in a population inhabiting the dry deciduous forest of the Ankarafantsika National Park in northwestern Madagascar during 1998, 2001, and 2003. The species showed a seasonal reproduction. The main mating season extended from May to June, as indicated by the presence of males with high testes volumes and estrus females. In the mating and early postmating season and in the postparturition season, sexes did not differ in body mass. Females had a significantly higher body mass than males in August and November, indicating pregnancy, which together with the presence of small infants in October and November implies that gravidity in females lasted for about 4–5 mo. All litters consisted of singletons. Individuals with body mass at the lower limit of the population either did not develop measurable testes volumes (males) or were not in estrus (females). They were probably juveniles from the previous birth season that achieved sexual maturity not before their second year after birth. The first data on reproduction suggest a low reproduction rate for Lepilemur edwardsi and a request for a higher conservation status than previously attributed and the need for further management strategies.     

Mating of captive thirteen-lined ground squirrels and the annual timing of estrus

Thirteen-lined ground squirrels (Spermophilus tridecemlineatus) have a single annual mating season in Michigan, beginning shortly after their spring emergence from hibernation. Captive females were studied during a 3-year period to determine relations among time of removal from the coldroom, vaginal estrus, and mating behavior. Following a 7-month period females spent in a coldroom, vaginal lavages were taken daily to monitor changes in estrous condition. Females removed from the coldroom about when free-living animals emerge from hibernation were in vaginal estrus within 24-48 hr and had an initial period of persistent estrus (ca. 3 weeks), followed by briefer (less than 1 week) and more sporadic estrous periods. Females left in the coldroom 3 weeks longer than normal had significantly briefer initial periods of vaginal estrus after being removed from the coldroom. Similarly, virgin Yearlings and virgin 2-Year-Olds had significantly briefer initial periods of estrus than nonvirgin Adults (greater than or equal to 2 years old). In 1985, eight of eight females paired with males mated within the first week after removal from the coldroom and subsequently produced litters. Mated females remained in vaginal diestrus from within a few days of mating until after parturition. In contrast, unmated females remained in prolonged vaginal estrus during this period. Females first paired with males 3 weeks after being taken from the coldroom failed to mate. In 1986, five of six females first paired with males 2 weeks after being removed from the coldroom similarly failed to mate. However, five of six females did mate that were removed from the coldroom 10 days after those in the previously described group and paired with a male 4 days after removal. This first report of reliable mating behavior in captive thirteen-lined ground squirrels should facilitate subsequent analysis of reproductive patterns in this species.     

Effects of hCG on folliculogenesis and fecundity in mink (Mustela vision Schreb)

The endogenous hormonal response obtained after reproductive organs are challenged by exogenous hormones is increasingly being used to predict presence of functional reserves and to apply this information to improve efficiency of managed breeding programs. With that in mind, the aim of the present study was to investigate the effect of a single treatment with hCG on folliculogenesis and fertility in standard 7-month-old mink females. The extent of stimulation following treatment was determined by examining patterns of vaginal smears. Characteristics of each cycle stage were: estrus, preponderance of cornified epithelial cells; proestrus, polygonal, elongate epithelial cells; anestrus, parabasal, intermediate and leucocyte cells. Smears exhibiting a mixed population of cells were categorized as being in transition between adjacent stages anestrus–proestrus or proestrus–estrus. The initial evaluations were done on Day 6 after hCG treatment. Histomorphometric examination of ovaries and uteri was done during seasonal anestrus (November) and in the breeding season (March). Vaginal cytology patterns were correlated with changes in folliculogenesis. A mean of 1.3 mature (Graafian) follicles were counted during estrus, while the mean number seen during anestrus, anestrus–proestrus and proestrus, were 0.4, 0.3 and 1.0, respectively. During the breeding season, in females that were not treated, the numbers of growing follicles decreased and maturing follicles increased, whereas females that came in estrus after treatment with hCG in November had increased numbers of both growing and maturing follicles. Fertility after breeding in hCG-treated females was increased by 9.2% (P<0.05) as compared to untreated females. Females showing the highest fertility rise (27%) were predominantly in the group that showed estrus after hCG treatment. We conclude that monitoring the response of the mink reproductive system to hCG stimulation in November may be a useful tool for identifying females of high fertility in the spring.     

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.     

Hormone-induced luteolysis on physiologically persisting corpora lutea in Eurasian and Iberian lynx (Lynx lynx and Lynx pardinus)

The Iberian lynx (Lynx pardinus) is the most critically endangered felid. A high reproductive success within the Iberian Lynx Conservation Breeding Program is crucial to maintaining the goal of reintroducing captive born offspring to the wild and thus increasing the population. Lynx follow a unique reproductive strategy with a monoestrous cycle and persisting CLs over many years. These persistent CLs constantly produce progesterone (on average 5 ng/mL) and are hypothesized to hinder a polyestrous cyclicity in lynx. The aim of this study was to evaluate whether artificial luteolysis can be achieved with common luteolytic drugs and if luteolysis would induce a second estrus naturally. We observed a functional regression of lynx CLs after artificial luteolysis with 2.5 μg/kg body weight PGF2α analogue (cloprostenol) administered three times every 16 hours. We could see a similar effect when combining cloprostenol with other drugs like an anti-gestagen (aglepristone) or a dopamin-agonist (prolactin-inhibitor, cabergolin) or by prolonging the cloprostenol administration to a total of 5 days. However, the sample size was too small to draw conclusions about which protocol is superior or if combining different drugs would result in a positive synergism. Neither structural regression of CLs nor subsequent spontaneous estrus induction was induced with any of these treatments. We suggest that a dose of 2.5 μg/kg body weight cloprostenol administered once daily over 3 to 5 days is sufficient for functional luteolysis in lynx. The next step would be to compare the success of estrus induction with or without the preceding artificial luteolysis.     

Aspects of reproduction in the eastern rufous mouse lemur (Microcebus rufus) and their implications for captive management

The eastern rufous mouse lemur is one of the smallest primate species. It inhabits the eastern rain forest of Madagascar. Its reproductive biology has not been examined because of its rarity in laboratories. We present the first data on reproduction and variation in reproductive success from a breeding colony of wild‐caught Microcebus rufus. The eastern rufous mouse lemur shows a seasonal change in testicular size and in the occurrence of estrus. Females had 2.5 cycles (range, one to four) per season. The estrous cycle length was 59 days (range, 51–66), the duration of vaginal opening during estrus was 7.5 days (range, 5–8), receptivity occurred on the third day of estrus, gestation length was 56.5 days (range, 56–57), litter size was two neonates (range, one to three). The frequency and duration of mating behavior varied widely among the pairs. Copulation seemed to occur on a single day per estrus within the first to fourth hour after light change to red light. In four cases (three pairs), copulation lasted between 15 and 240 seconds. Breeding success can be increased by choosing mates carefully. Microcebus rufus seems to be a seasonal breeder like its sibling species Microcebus murinus. In wild‐caught animals, males seemed to adapt quickly (first season) to the conditions of captivity, whereas in the females, individual variation (first to third season) in reproductive activity was observed. Air humidity of >60% seems to facilitate the breeding success in wild‐caught pairs. First pregnancy and successful rearing of offspring occurred in the second and fourth year of captivity in two of three females. Wild‐caught eastern rufous mouse lemurs seemed to demonstrate variation in adapting to the conditions of captivity with regard to sex and individuality. Zoo Biol 20:157–167, 2001. © 2001 Wiley‐Liss, Inc.     

Age-related hormonal differences in cycling squirrel monkeys (Saimiri boliviensis boliviensis)

This study was planned to evaluate the poor reproductive performance of aged squirrel monkeys in a self-sustaining breeding colony. Two groups of monkeys aged 6–8 years (Group 1), and >12 years (Group 2) were evaluated. During the midbreeding season, daily blood samples were obtained for a period of 35 days from 10 animals in each group. Blood samples were assayed for serum estradiol (E), progesterone (P), and bioassayable luteinizing hormone (bio-LH) concentrations and the data were analyzed by ANOVA (analysis of variance). Bio-LH surges were less frequent in the aged breeders (Group 2). Total P output during periovulatory period (day ?;3 to day + 3) and the total P output during the luteal phases of the estrus cycles were significantly lower in aged squirrel monkeys (Group 2, P < 0.003). Although E peaks occurred less frequently in Group 2, they had higher concentrations as compared to Group 1 (P < 0.003). Cumulative periovulatory and luteal phase E levels did not differ between the two groups. The reduction in P output in aged squirrel monkeys may interfere with proper implantation, thus contributing to the lower pregnancy rate observed in this age group. The decreased frequency of bio-LH surges indicated less frequent ovulations in the aged animals which may further impair reproduction with aging. © 1994 Wiley-Liss, Inc.     

圈养猞猁多雄交配雄性的成功繁殖

研究了笼养猞猁多雄交配的结果以及雄性的成功繁殖。雄兽与发情雌兽随机配对,其繁殖成功(所产生的后代数量)不取决于与雌兽的交配顺序、交配次数与持续时间、遗传关系或雄兽的行为特征,但似乎取决于精子质量,特别是取决于形态正常精子的百分率。繁殖成功的雄兽比其竞争对手具有更多的形态正常的精子,似乎更能成功地诱发交配雌兽的排卵。证实了4窝(占总窝数的20%)幼兽的双重父亲身份。在所有情形下, 2雄1雌的交配间隔为24h 。     

Effect of season on hormonal profile and some biochemical parameters at different stages of estrous cycles in Baladi goats

Understanding the seasonal patterns of estrus cycle in caprine is crucial to develop the efficient breeding plans in the subtropics. Thus, the aim of the current research was to evaluate the effects of breeding season on hormonal profile and blood biochemical indices at different stages of estrus cycle in normal breeding or out-of-season breeding in goats. Forty-four Baladi goats were monitored for a period of eight months (July–February). Baladi goats exhibit a normal seasonal breeding (NS) at midsummer and continue through the autumn season (68%), with a considerable percentage of females having estrus signs during out-of-season (OS) period (32%). At the mid and late luteal phases of estrus cycles, the NS breeding group had significantly higher serum progesterone level than that reported in the OS group (p = 0.013 and 0.039, respectively). At the estrus and late luteal phases of estrus cycles, the NS breeding group had significantly higher serum β-estradiol level than that reported in the OS group (p = 0.022 and 0.001, respectively). Compared to the OS group, the NS breeding group had significantly higher serum cholesterol at the mid and late luteal phases of estrus cycle (p = 0.001 and 0.016, respectively), and higher serum glucose level in the early luteal phase of the cycle (p = 0.009). In conclusion, the NS breeding goats had superior progesterone (mid-luteal and late luteal phases) and estradiol (estrus and late luteal phases) profiles than that reported in the OS group. This may indicate specific approaches to maintain the breeding efficiency of goats during the out-of-season period.     

Functional anatomy of the female genital organs of the wild black agouti (Dasyprocta fuliginosa) female in the Peruvian Amazon

This study examined anatomical and histological characteristics of genital organs of 38 black agouti females in the wild in different reproductive stages, collected by rural hunters in the North-eastern Peruvian Amazon. Females in the follicular phase of the estrous cycle had greater antral follicle sizes than other females, the largest antral follicle measuring 2.34mm. Antral follicles in pregnant females and females in luteal phase of the estrous cycle had an average maximum diameter smaller than 1mm. In black agouti females in follicular phase, some antral follicles are selected to continue to growth, reaching a pre-ovulatory diameter of 2mm. Mean ovulation rate was 2.5 follicles and litter size was 2.1 embryos or fetuses per pregnant female, resulting in a rate of ovum mortality of 20.8%. Many follicles from which ovulation did not occur of 1-mm maximum diameter luteinize forming accessory CL. The constituent active luteal tissues of the ovary are functional and accessory CL. Although all females had accessory CL, transformation of follicles into accessory CL occurred especially in pregnant females, resulting in a contribution from 9% to 23% of the total luteal volume as pregnancy advances. The persistence of functional CL throughout pregnancy might reflect the importance for the maintenance of gestation and may be essential for the continuous hormonal production. The duplex uterus of the agouti female is composed by two completely independent uterine horns with correspondent separate cervices opening into the vagina. In pregnant females, most remarkable observed uterine adaptations were induced by the progressive enlargement caused by the normal pregnancy evolution. The wild black agouti showed different vaginal epithelium features in accordance with the reproductive state of the female.     

圈养马麝(Moschus sifanicus)发情交配节律的比较研究

在1997～2000年间,甘肃兴隆山麝场的圈养马麝发情交配的时间节律保持相对年间恒定,1996年麝场进行了大规模的圈群间动物调整,导致该年的马麝圈群进入发情较迟,发情持续时间也较其他年份长。总体上,圈养马麝的发情持续时间达3个月,而66％的的发情交配发生于1个月内（从11月21日～12月21日）,发情季节（75％的发情完成累计时间）长36天。雌性圈养马麝发情的时间格局受圈养环境的季节性因子影响。饲养人员的饲养风格及各个饲养区内雌性马麝的社会行为的调节效应,各饲养区动物的发情时间格局有显著差异。年龄可影响马麝的发情交配,5．5岁龄以上的马麝发情定时更早。上一年度的繁殖成功与否和当年动物发情迟早无显著相关。野捕圈养麝群和其F1代圈群间的发情时间格局无显著差异。有较多发情周期的个体并不比发情周期仅1～2次的个体更早进入发情。     

Circadian Activity Patterns of Canada Lynx in Western Montana

Abstract: We recorded activity data for 6 male and 5 female lynx in winter and 3 male and 6 female lynx during summer in western Montana, USA, using motion-sensitive radiocollars. Lynx diel activity appeared to vary by sex, season, and reproductive status. During summer, male lynx exhibited a crepuscular activity pattern, whereas females with kittens remained active throughout the photoperiod. During winter, lynx of both sexes were most active during the afternoon and early evening. Although we observed no evidence that predation risk drove lynx activity patterns, such patterns may be a function of kitten-rearing activity, thermoregulatory strategies, and foraging behavior.     

Comparative patterns of adrenal activity in captive and wild Canada lynx (<Emphasis Type="Italic">Lynx canadensis</Emphasis>)

Stress and animal well-being are often assessed using concentrations of glucocorticoids (GCs), a product of the hypothalamic–pituitary–adrenal axis. However, GC concentrations can also be modulated by predictable events, such as changes in season or life history stage. Understanding normative patterns of adrenal activity is critical for making valid conclusions about changes in GC concentrations. In this study, we validated an assay for monitoring fecal glucocorticoid metabolites (FGM) in Canada lynx. We then used this technique to assess patterns of adrenal activity in Canada lynx across several contexts. Our results show that captive lynx have higher FGM concentrations than wild lynx, which may be related to differences in stress levels, metabolic rate, diet, or body condition. We also found that FGM concentrations are correlated with reproductive status in females, but not in males. For males, seasonal increases in FGM expression coincide with the onset of the breeding season, whereas in females, FGM increase toward the end of the breeding season. This information provides a valuable foundation for making inferences about normative versus stress-induced changes in adrenal activity in Canada lynx.     

Estrous state influences on investigative,aggressive, and tail flicking behavior in captive female Asian elephants

Females of species that live in matrilineal hierarchies may compete for temporally limited resources, yet maintain social harmony to facilitate cohesion. The relative degree of aggressive and nonaggressive interactions may depend on the reproductive condition of sender and receiver. Individuals can benefit by clearly signaling and detecting reproductive condition. Asian elephants (Elephas maximus) live in social matrilineal herds. Females have long estrous cycles (14–16 weeks) composed of luteal (8–12 weeks) and follicular (4–8 weeks) phases. In this study, we observed the behavior of four captive Asian elephant females during multiple estrous cycles over 2 years. We evaluated whether investigative, aggressive, and tail flicking behaviors were related to reproductive condition. Investigative trunk tip contacts showed no distinct pattern by senders, but were more prevalent toward female elephants that were in their follicular compared with their luteal phase. The genital area was the most frequently contacted region and may release reproductively related chemosignals. Aggression did not differ significantly with estrus; however, rates of aggression were elevated when senders were approaching ovulation and receivers were in the luteal phase. Females in the follicular phase may honestly advertise their condition. Contacts by conspecifics may serve to assess condition and reduce aggression. A behavior termed “tail flicking” was performed mainly during the mid‐follicular phase when estrogen and luteinizing hormone levels are known to spike. Tail flicking may disperse chemical signals in urine or mucus as well as act as a tonic signal that could provide a means of anticipating forthcoming ovulation by elephants and also for human observers and caretakers. Zoo Biol 27:167–180, 2008. © 2008 Wiley‐Liss, Inc.     

The Reproductive State of Female Voles Affects their Scent Marking Behavior and the Responses of Male Conspecifics to Such Marks

During the breeding season, the reproductive condition of female mammals changes. Females may or may not be sexually receptive. We conducted a series of experiments to determine whether reproductive condition of female meadow voles affects their scent marking behavior as well as the scent marking behavior of male conspecifics. In expt 1, females in postpartum estrus (PPE females) deposited more scent marks than females that were neither pregnant nor lactating (REF females) or ovariectomized females (OVX females). In expt 2, male voles scent marked more and deposited more over‐marks in areas marked by PPE females than by REF and OVX females. In expt 3, PPE females deposited more scent marks and over‐marks in areas marked by males than did females in the other reproductive states. The results of these experiments showed that male and female voles may vary in the number, type and location of scent marks they deposit in areas scented by particular conspecifics.     

Fecal endocrine monitoring of reproduction in female snow leopards (Uncia uncia)

Although the snow leopard (Uncia uncia) is a common endangered felid species in zoos, little is known about the complex endocrine interactions controlling ovarian function and conception in this species. The goal of this work was to characterize ovarian activity throughout the estrous cycle, nonpregnant luteal phase (pseudopregnancy), and gestation in female snow leopards. This goal was accomplished using an enzyme immunoassay to measure fecal concentrations of estrogen metabolites (E) and progesterone metabolites (P). Fecal samples were collected from 12 female snow leopards (ages 18 months to 18 years) during one to three breeding seasons. In each breeding season, the majority of females (78%, 88%, and 100%, respectively) began to exhibit ovarian activity in December or January. The estrous cycle, defined by the first day of estrus (E ≥ 2 × basal concentration) to the first day of the subsequent estrus, was 12.7 ± 0.6 days (n = 145 cycles). Estrus lasted 4.3 ± 0.4 days with mean concentrations of fecal E during the follicular phase (1661 ± 139 ng/g feces) increasing 3.2-fold above basal concentrations (515 ± 32 ng/g feces). No spontaneous ovulations were observed in any of the cycling females. Nonpregnant luteal phases were observed in eight females that bred but did not become pregnant. The length of the nonpregnant luteal phase ranged from 11 to 72 days (45.7 ± 5.7 days; n = 10) with mean concentrations of fecal P during the luteal phase (12.46 ± 1.7 μg/g feces) increasing 6.2-fold above basal concentrations of P (2.01 ± 0.2 μg/g feces). Three of the females in the study became pregnant and gave birth after a gestation of 93 (n = 2) and 95 (n = 1) days. Fecal P concentrations during pregnancy increased to 11.64 ± 1.3 μg/g feces, or 5.8-fold above basal concentrations. The results of this study provide a comprehensive characterization of reproductive endocrinology in snow leopards, and confirm that fecal hormone monitoring is an effective way to monitor female snow leopards throughout the breeding season.     

The reproductive biology of a free-ranging troop of Japanese monkeys

Quantitative data on the reproductive biology of Japanese monkeys (Macaca fuscata), especially of females, are reported here. Arashiyama B troop shows stable annual breeding periodicity, and has mating seasons between October and March. In mating seasons, females show estrus with rather consistent cyclicity, and are in estrus for a total of 35 days on an average. The mean length of estrous cycle is 34 days. Although most females show estrus inter-menstrually, some show peri-menstrually; i.e., estrus does not always synchronize strictly with ovulation. Pubescent females between 3.5 and 6.5 years show estrus, but with low sexual activity. Middle-aged females between 7.5 and 16.5 years show high sexual activity with high conception rate. Old-aged females over 17.5 years show low sexual activity. Females with surviving infants have lower sexual activity than those without infants. There is found no significant correlation between female's ranking and sexual activity. This study was financed partly by the Cooperative Research Fund of the Primate Research Institute, Kyoto University.     

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]。