Perinatal exposure to progesterone, estradiol, or mifepristone affects sexual differentiation of behavior in opossums (Monodelphis domestica)

The effects of perinatal exposure to progesterone (P) and estradiol (E) on sexual differentiation of behavior and morphology were examined by treating male and female gray short-tailed opossums on postnatal day 8 with progesterone alone (P), P plus estradiol (E) (PE), the P receptor antagonist mifepristone/RU486 (MIF), or corn oil control (C) and gonadectomizing them before puberty. When given female hormone replacement therapy in adulthood and tested with intact stimulus males, MIF animals showed less female-typical aggressive threat behavior than animals in other treatment groups. Stimulus males scent marked in more tests involving females than males and in more tests involving MIF animals than animals in other treatment groups. Body weight was lower in females than in males and was lower in MIF animals than in animals in other treatment groups, and P females failed to show female-typical genital locks after copulation. Sexual receptivity was similar in males and females and, while not decreased by any perinatal hormone treatment, was higher in PE males than in animals of either sex in any treatment group. These findings suggest that perinatal exposure to P is associated with the organization of feminine threat behavior and the defeminization of attractivity, body weight and genital anatomy in this marsupial. Reasons for these findings and for why female sexual receptivity is enhanced by perinatal exposure to exogenous E only in an endogenous masculine environment are discussed.     

Influence of age and individual identity in the use of breeding colony habitat by male Weddell seals in Erebus Bay,Antarctica

Male–male contest behavior can contribute to spatial distributions of male pinnipeds during breeding seasons. To maximize breeding opportunities, the most competitive males would be expected to be surrounded by the highest numbers of reproductive-age females. As information regarding fine-scale spatial ecology of Weddell seals is lacking, we performed an exploratory study using kernel density analyses to evaluate age-specific habitat use of male Weddell seals in Erebus Bay, Antarctica. Additionally, we investigated the relationship between age and number of surrounding reproductive-age females using a competing set of regression models in a Bayesian framework that considered different functional forms of age while incorporating individual heterogeneity. As male adult Weddell seals aged, to at least 20 years, they were more likely to be found in areas associated with the greatest densities of reproductive-age females, but individual heterogeneity also influenced the number of reproductive-age female neighbors. The youngest males tended to haul out in offshore areas associated with better hunting, and older males tended to settle in more nearshore areas associated with more pup production. Our findings from this preliminary investigation indicate that male Weddell seal spatial behavior during the breeding season varies with age and individual and might be related to reproductive activity.     

Roosting patterns in a captive colony of short-nosed fruit bat Cynopterus sphinx (Vahl)

Development of roosting patterns under a limited resource was studied in the short-nosed fruit bat C. sphinx in captivity. Spatial fidelity during the resting period (day time) and the individual male bat's presence/absence in the roost (occupancy index) were estimated during the active period (night time). Results show the presence of three groups on the basis of spatial fidelity. The first group was associated with the tent consisting of a harem male and seven females. The second group stayed near to the harem. The third group consisting of two males showed little occupancy index and no spatial fidelity. Female turnover between the first and second groups, and harem male replacement were observed. These findings of male groupings and female loyalty on the basis of "resource", suggest that resource defence polygyny is the primary mating strategy in C. sphinx.     

Infanticide in black capuchin monkeys (Cebus apella nigritus) in Iguazú National Park, Argentina

We report here one observed and two potential cases of infanticide during a brief period of 1 month after a dominant male replacement in one group of black capuchin monkeys in Iguazú National Park, Argentina. We also compile infant disappearances and demographic data in seven groups followed from 1-14 years. Behavioral and molecular data showed that the probability that an infanticidal male would kill his own progeny is very low in this species. Females that lost infants less than 6 months old had shorter interbirth intervals than females whose infants survived (14.12 ± 5.32 months, n=17 vs. 20.42 ± 5.65 months, n=34). Females whose infants die shortly after takeovers mate with the presumed infanticidal male during the most fertile days of their subsequent estrous periods giving this male a high probability of siring the new progeny. We recorded 181 proceptive periods and 52 births from 18 adult females in two groups. Most proceptive periods were concentrated during a conception season, but there was an increase in sexual behavior after male takeovers. Seven females copulated while pregnant after the observed male takeover, an unusual behavior in this species in years of group stability. Of 24 infants born during takeover years, 62.5% did not survive the first year, whereas only 22.5% of 80 infants died in years without male replacements. We found a significant positive association between infant mortality and male takeovers, but not with food provisioning. The main cause of infant mortality in this population is associated with male takeovers. Our results suggest that infanticide can have an important effect on the behavior of this species, selecting for female behaviors that function to reduce infanticide risk.     

Influence of the Male Axillary Extracts on Regulation of Menstrual Cycles in Women

The effect of male axillary extract on the length and regularity of the menstrual cycle in women was studied in a long-term experiment (9 months). The male secret extract had no statistically significant influence on the menstrual cycle duration in the reproductive-age women (21–45 years) with normal (26–32 days) and regular cycles or in women with abnormally short (<26 days) cycles. In the group of the reproductive-age women with irregular and abnormally long (>32 days) cycles, as well as in the group of the premenopauseage women (46–51 years) with irregular cycles, the secret extract caused a significant shortening of the menstrual cycle as compared to the control. The effect was preserved for at least two months after the exposure completed.     

Influence of replacement rate on the welfare of sows introduced to a large dynamic group

This experiment investigated the effects of replacing 10, 20, 30 or 40% of a dynamic group of forty sows on the welfare of newly-introduced animals. The experiment was replicated five times, using a total of 200 multiparous sows. Replacements took place at 3 week intervals, and 3 days prior to sows being added to the group the same number of animals were removed from the group. Sows were added to the dynamic group as pre-formed groups of four animals which had resided together for a period of 5 weeks beginning directly after their piglets were weaned. Replacement rate did not appear to influence overall levels of aggression to which newly-introduced animals were exposed on the day of mixing, however aggression among newly-introduced animals increased significantly as replacement rate increased between 20 and 40% (P<0.05). Injury levels measured 1 week post mixing did not differ significantly between treatments. Newly-introduced sows in the 10% replacement rate treatment spent more time in slatted areas and less time in kennel areas during the first week post mixing than newly-introduced sows in other treatments (P<0.05). In addition, during the first week post mixing when sows in the 10% replacement rate treatment entered kennel areas they spent less time lying down (P<0.05), and when they did lie down they spent less time lying in contact with other animals and more time lying close to the wall (P<0.05) compared to newly-introduced sows in other treatments. It is suggested that this type of behaviour represents intimidation from resident sows. Newly-introduced sows in the 20, 30 and 40% replacement rate treatments showed similar lying behaviour. In all treatments the newly-introduced sows showed a significant increase in the time spent in kennel areas, and the time spent lying in contact with ‘resident’ sows during the first week post mixing, which suggests that the process of social integration with the resident group had begun. The results of the present study suggest that the welfare of newly-introduced sows in dynamic groups may be compromised when replacement rates of 10% are used. There appears to be no additional welfare benefit associated with increasing replacement rate above 20%.     

青藏铁路对雄性藏羚行为时间分配的影响

行为时间分配是动物对资源获取和风险防御的权衡,受到诸多因素影响。本研究采用目标动物观察法记录了可可西里冬季（交配季）雄性藏羚的行为表现,并将行为分为觅食、警戒、卧息、移动和“其他”5种类型。首先,本文通过对比青藏铁路运营前后两个交配季（2003-2004年建设期和2017-2018年运行期）之间雄性藏羚的行为时间分配差异,探讨青藏铁路的出现对雄性藏羚行为的影响。随后,基于2017-2018年交配季雄性藏羚的行为数据,分析了年龄对其行为时间分配的影响。结果表明：与建设期相比,雄性藏羚的觅食和“其他”行为时间比例明显增加,而警戒和卧息的行为时间比例显著降低,这说明铁路稳定运营后对雄性藏羚的影响降低。交配群中成年雄性藏羚的警戒、移动,以及“其他”行为中的繁殖行为的时间比例显著高于亚成体,而觅食和卧息行为时间比例显著低于亚成体, 这与交配群中不同年龄雄性个体所处的地位等级有关。成年雄性藏羚在交配群中占据主导地位,拥有更多配偶资源,增加警戒和移动,减少觅食和卧息有助于其维持交配群的稳定。     

Aggression with mixed age-sex groups of bolivian squirrel monkeys following single animal introductions and new group formations

The social organization of the Bolivian squirrel monkey (Saimiri boliviensis boliviensis) is thought to be sexually segregated, with males and females forming separate social groups during the nonbreeding season. To investigate the influence of this social order on patterns of aggression, controlled single animal introductions within established groups and establishment of new groups were studied in a systematic manner. Behavioral observations were made using an all-occurrences technique to sample all agonistic interactions. In study I, 4 animals of each age-sex class (adult males and females, juvenile males and females) were introduced one at a time into 4 different social groups composed of 1 adult male and 8 to 10 adult females. Behavioral observations were made prior to and after the introductions. Newly introduced adult males received significantly more contact aggression than other age classes. Only the adult females increased aggression after the introduction of new animals. In study II, new social groups were formed and behavioral observations were made following formation. One group was formed from 7 pairs of familiar females and an unfamiliar adult male. This group had a high frequency of aggression during the first half hour, with contact aggression rising to peaks at 3 and 5 h. The second group consisted of 10 familiar females, 2 pairs of familiar females and an unfamiliar male. There was a significant peak in contact aggression 3 h into the observation.     

Adult male replacement and subsequent infant care by male and siblings in socially monogamous owl monkeys (<Emphasis Type="Italic">Aotus azarai</Emphasis>)

Owl monkeys (Aotus azarai) are small, territorial, socially monogamous primates that show intense infant care by the adult male in the group. It has been hypothesized that male care may be adaptive because it increases offspring survival and/or reduces the metabolic costs to the female of raising the offspring. Alternatively, males may provide care even when they are not related to the infants to increase future reproductive opportunities. We describe changes in infant care patterns that took place after the eviction of the resident male by a solitary male in an owl monkey population in the Argentinean Chaco. The resident male and mother provided all infant care during the first month of life of the infant, until the male was evicted. During the three-day male replacement event, care of the infant was shared among the mother, a four-year-old sister, and a one-year-old brother. The new male began contributing to infant care soon after entering the group, carrying, and interacting socially with the infant in much the same way as any male regularly does. However, despite receiving biparental care from both the original and new resident males, the infant disappeared at the age of four months and was presumed dead. These are the first reports of care by sibling and by non-putative fathers in wild owl monkeys. Given the significant amount of time that new pairs of owl monkeys spend before reproducing, it is possible that male care in owl monkeys functions as mating effort as much as or more than parenting effort.     

Effects of HCG or gonadoreline on seminal parameters and plasma testosterone levels in young male rabbits

The effect of successive HCG or Gonadoreline injections on some reproductive parameters in 21 young male rabbits, aged from 4 to 4.5 months, has been studied. Animals were randomly allocated in three groups of seven to receive weekly (on each Monday) i.m. injections of 20 mg Gonadoreline, 50 IU HCG, or 0.5 ml Saline solution, respectively. The ejaculate from each male was collected and analysed twice a week (Tuesday and Friday). Higher sperm volumes were observed on the first week after Gonadoreline administration compared to the other groups (p < 0.05), and lower values during the second week in the Control group vs. Gonadoreline group (p < 0.05). Sperm volume increases after the 3rd week in Control animals (p < 0.05). When considering the global period studied, mean sperm volumes achieved after Gonadoreline treatment were higher than in HCG or Control group. Despite the random distribution of the animals to each treatment, and although throughout the experiment more ejaculates were discarded in the Gonadoreline group, the final number of doses obtained per ejaculate was higher in this group followed by HCG treated animals. Globally, the mean sperm concentration of the Control group during the entire studied period was significatively lower compared to the other groups (p < 0.001). No sperm motility differences were detected among the groups (p < 0.1174). HCG injections caused a significative increase in plasma testosterone concentration during the first and second week (p < 0.001) and similar plasma levels were observed in all groups afterwards. No direct plasma testosterone increasing levels owed to Gonadoreline injections were detected, probably due to the frequency of blood sampling (once a week).     

Influence of chlormadinone acetate on hypothalamic differentiation in male rats

The effect of chlormadinone acetate on adult male rats during the hypothalamic differentiation phase was studied. Psychic intersexuality with increased male and increased female sexual behavior was observed both before and after postpuberal castration and sex hormone replacement. Organ weights of testes, seminal vesicles, and ventral prostrates were normal, but penis and adrenal gland weights were significantly smaller. Body growth was also significantly reduced compared with control animals. The effects of chlormadinone acetate on androgen-dependent brain differentiation are discussed and compared with analogous effects of cyproterone acetate and orchidectomy.     

The effect of alcoholization on the behavioral reactions of rats in an 8-arm radial maze

The influence of 20% alcohol consumption on training of low-active rats in 8-arm radial maze was studied. One group of animals was trained before and the other group after the alcoholization. All the animals acquired the conditioned reaction in the radial maze. However, the behavioral difference between the groups consisted in spatially-motor asymmetry. The rats trained before the alcohol consumption had less stereotyped behavior and more distinctly preferred to enter the maze arms at the angle of 45 degrees than the animals trained after the alcohol consumption. After the alcohol consumption, rats more frequently refused from behavioral task performance in comparison with the animals trained after the alcoholization. The influence of alcohol consumption of learning and memory in low-active rats is discussed.     

Individual characteristics of the nociceptive sensitivity of rats during the formation of a negative emotional reaction

Changes in dynamics of nociceptive sensitivity in male rats of Wistar strain were studied during formation of negative emotional reaction. The procedure of blood's taking from the tail after its tip's amputation was used as negative emotional factor. The animals were divided into six groups by the criterion of individual properties of nociceptive sensitivity dynamics. On the whole it was found to decrease. Besides, one more group (the seventh group) was found with profound hypoalgesia caused by action of the negative emotional factor. It was also shown that formation of negative emotional reaction in two groups was not accompanied by changes of nociception. The data suggest a selective influence of negative emotional factor on nociceptive sensitivity.     

Male and female mice living in differently-sized groups

Summary The influence of crowding in different group sizes on the metabolism of serotonin (5-HT) in six different brain areas and on some peripheral data in male and female mice was investigated. In the cortex, the diencephalon and in the basal ganglia, the 5-HT turnover of male mice increases with group size. The females react differently (Figs. 2, 3, 4). The densityinduced changes in the 5-HT metabolism of the mesencephalon correlated individually with the locomotor reactivity of the animals in an open-field (Figs. 8, 9). The septal area is the only part of the brain in male and female mice in which the 5-HT turnover increase depends on group size (Fig. 5).We wish to thank the Deutsche Abbott GmbH which supplied us with pargyline.     

Performance correlates of social behavior and organization: Effects of group formation on operant performance in rhesus monkeys (M. mulatta)

The performance of six adult rhesus monkeys on a fixed interval 1-min reinforcement schedule was examined under conditions where the reinforcement probabilities were either 1.00 or .80. The animals were tested with a reinforcement probability of 1.00 immediately after removal from their social group, tested again several months later with reinforcement probabilities of 1.00 and .80, and then retested with a reinforcement probability of .80 before, during, and after the formation of a new social group with the six monkeys. The results supported an earlier report in which it was found that high ranking animals responded at a lower rate under a reinforcement probability of 1.00 than did low ranking animals and that the former also had a higher ratio of nonreinforced to reinforced responses than the lower ranked animals. These relationships were present in five of the six animals immediately after removal of the animals from their original group and during and after formation of the new group. They did not appear on tests conducted after the animals had been out of a social group for several months. A third result was a suppression of operant performance which appeared in all animals following group formation. The magnitude and duration of this effect was inversely related to social rank and the time the animal had been a member of the group. The data are discussed in terms of a carry-over of the effects of recent social experience on two factors: a more deliberate rate of response by higher ranking animals under 100% reinforcement and an inhibition of response bursting following omission of reinforcement by the lower ranking monkeys. Supported by USAMRDC Contract No. DADA 17-73-C-3007.     

Movements and activities of male black‐tailed gulls in breeding and sabbatical years

Long‐lived animals sometimes skip one or more breeding seasons; however, little is known about their movements and activities during such ‘sabbatical’ periods. Here we present novel data on year‐round movements and activities of two male black‐tailed gulls Larus crassirostris during a sabbatical year. We compare the data with those in a year when they bred and with those of two other breeding males. The year‐round migration routes of two sabbatical males were consistent with those of the breeding males: they returned to the breeding area but did not visit the colony in the sabbatical year. They landed more frequently on water (a potential index of foraging effort) during the non‐breeding autumn and winter prior to the sabbatical year than before breeding. Sabbatical gulls may forage more intensively to recover body condition immediately after breeding.     

Effects of castration and androgen replacement on male courtship behavior in the red-sided garter snake (Thamnophis sirtalis parietalis)

Following artificial hibernation, sexually mature male garter snakes (Thamnophis sirtalis parietalis) exhibited a decline in courtship behavior irrespective of castration, sham operation, or castration with testosterone replacement therapy. Behavior declined more rapidly in castrated animals with testosterone replacement than in castrated or sham-operated animals. In sham-operated animals, the decline in courtship was accompanied by changes in testicular weight and spermatogenic state from small spermatogenically inactive testes to large spermatogenically active testes. Serum androgen levels were more than fourfold greater in sham-operated animals than in castrated animals; cell height of the androgensensitive renal sex segment was greatest in castrated animals with testosterone replacement and least in castrated animals. These findings indicate that following artificial hibernation, male courtship behavior of T.s. parietalis is independent of the presence of the testes.     

Pituitary-testicular axis abnormalities in immature male hypothyroid rats

The pituitary-testicular disturbances which follow the onset of hypothyroidism were studied in immature male Wistar rats rendered hypothyroid by treatment with methimazole (MMI) given in drinking water, starting at 40 days of age. Half of the animals continued on MMI (MMI group) up to 140 days of age; the remaining rats were withdrawn MMI at 100 days and injected thereafter s.c. with 3 micrograms of T3 daily, during the last 40 days (MMI + T3 group). Ten rats were used as controls (C group). Hypothyroidism induced in immature animals significantly decreased serum T4, T3, LH, PRL, and testosterone levels, and also impaired the normal growth of body and sex accessory glands. T3 replacement therapy helped to normalize serum hormonal levels, but the body and sex accessory gland weights were not fully corrected. Hypothyroidism also reduced the [125I]LH/hCG binding sites of testicular homogenates. T3 replacement was not able to improve the binding; nonetheless, the hormone-receptor affinity constant remained unaltered among the groups. Leydig cell responsiveness to hCG stimulation in vitro (0-82 nM) showed impaired testosterone production in the MMI group (25% of that found in the C group) and also in the MMI + T3 group (80% of that found in the C group). These data demonstrate that induction of hypothyroidism in the immature male rat leads to alterations in serum LH, PRL and testosterone levels, and suggest that thyroid hormones have a modulating action on the testis as far as LH-mediated testosterone secretion is concerned.     

Infant Mortality in Black-and-Gold Howlers (Alouatta caraya) Living in a Flooded Forest in Northeastern Argentina

Ecological and social factors have a significant effect on infant survivorship in nonhuman primates. We present 6293 group-months of infant birth and mortality data for 29 groups of Alouatta caraya inhabiting a flooded forest in northeastern Argentina, collected over 1.5–8?yr depending on the group. We tested whether infant mortality was a response to the effects of flooding on food availability and whether male takeovers resulted in greater opportunities for infanticide. During our study, 43 of 113 infants died at a mean age of 5?mo. In 24 cases the cause of death was unknown. In the remaining 19 cases infant deaths were attributed to periods of intense flooding (N?=?8), replacement of the breeding male (N?=?8), problems associated with birth (N?=?2), and injuries during an intergroup encounter (N?=?1). Flooding reduced the availability of mature leaves, which appeared to play an important role in the ability of mothers to nurse their offspring. Male replacements occurred in four social groups that contained only one fully adult male. Infant mortality was significantly higher in groups that experienced male replacement compared to groups without male replacement. These results indicate that infant mortality in Alouatta caraya is affected by several factors—natural disasters, maternal condition and food availability, infanticide after male replacement, and possibly disease and predation—each of which needs to be evaluated to understand the history and demography of this primate population.     

Habituation of western gorillas: the process and factors that influence it

Habituation of western gorillas to human presence is generally an expensive, lengthy and difficult process. Here we describe the habituation process for two groups of western gorillas at the Mondika Research Center, with the hope that the lessons we learned will facilitate future gorilla studies. We expand upon earlier studies by describing the process through complete habituation for both males and females, and for more than one group. The major obstacle to habituation was developing sufficient tracking skills to follow gorilla trail on a daily basis. Once this was achieved, the silverback became semi-habituated (i.e. ignoring human presence during half of contacts) within a year, although the majority of group females continued to avoid humans. As female presence at contacts increased, a period of male recidivism followed, requiring an additional year before his complete habituation was reached. Habituating the females took longer than the male, but we found, contrary to earlier studies, that it consisted of the same stages, including avoidance, aggression, and curiosity before habituation. We compare results between groups and across sites and discuss how factors such as tracking abilities, group size and cohesion, population density and home range overlap, and the manner of approaching gorillas during contacts influence the habituation process.