定量评估豢养长江江豚个体间的优势关系

2000年1—4月和2000年4月—2002年4月,分别连续3个月和2年观察了中国科学院水生生物研究所白鱀豚馆6头长江江豚（3雌3雄,8个不同组合群）个体间发生的3种交互关系,即接近—逃开、接近—接触和接近—尾鳍击打。在累计8,162min的观察时间内,共观察到这些交互关系1,685次。本研究将江豚个体间发生的这3种交互关系作为个体间优势关系的指示,并分别给交互双方赋予不同的分值,采用优势比分矩阵方法定量分析了江豚个体之间的优势关系。结果表明江豚群体内存在优势关系。同性别个体之间,优势关系与年龄和饲养时间有关,年龄大的个体比年龄小的个体具有优势,饲养时间短的个体比饲养时间长的个体具有优势。但是,异性成年个体之间,优势关系通常是可变的。     

Quantitative histology of the seasonal changes in the gonads of summer whiting, Sillago ciliata

The histology of the gonads of free and captive summer whiting, Sillago ciliata , were compared to assess the potential of this fish for aquaculture. There were no qualitative differences between the free and captive males: both completed spermatogenesis through to spermiation. The captive females were non-reproductive, reaching only the vitellogenic stage before the eggs were resorbed by atresia.
A reproductive score was devised to assess reproductive potential in the comparison of the two populations. The females in the captive population had lower reproductive potentials, as shown by the score, and started development a month later than the normal free population. The captive males had higher reproductive scores than the free fish but they were also not spawning and, therefore, the higher score indicated that this potential was not realized. The score provides a standard against which experimental results can be compared and subsequently assessed.     

Causes and correlates of calf mortality in captive Asian elephants (Elephas maximus)

Juvenile mortality is a key factor influencing population growth rate in density-independent, predation-free, well-managed captive populations. Currently at least a quarter of all Asian elephants live in captivity, but both the wild and captive populations are unsustainable with the present fertility and calf mortality rates. Despite the need for detailed data on calf mortality to manage effectively populations and to minimize the need for capture from the wild, very little is known of the causes and correlates of calf mortality in Asian elephants. Here we use the world''s largest multigenerational demographic dataset on a semi-captive population of Asian elephants compiled from timber camps in Myanmar to investigate the survival of calves (n = 1020) to age five born to captive-born mothers (n = 391) between 1960 and 1999. Mortality risk varied significantly across different ages and was higher for males at any age. Maternal reproductive history was associated with large differences in both stillbirth and liveborn mortality risk: first-time mothers had a higher risk of calf loss as did mothers producing another calf soon (<3.7 years) after a previous birth, and when giving birth at older age. Stillbirth (4%) and pre-weaning mortality (25.6%) were considerably lower than those reported for zoo elephants and used in published population viability analyses. A large proportion of deaths were caused by accidents and lack of maternal milk/calf weakness which both might be partly preventable by supplementary feeding of mothers and calves and work reduction of high-risk mothers. Our results on Myanmar timber elephants with an extensive keeping system provide an important comparison to compromised survivorship reported in zoo elephants. They have implications for improving captive working elephant management systems in range countries and for refining population viability analyses with realistic parameter values in order to predict future population size of the Asian elephant.     

A condition dependent link between testosterone and disease resistance in the house finch.

Testosterone has recently been proposed as a link between male quality and health and the expression of sexual traits. We investigated the relationship between testosterone and measures of the individual condition and health of males in a natural population of house finches (Carpodacus mexicanus). We also conducted a captive experiment in order to test for the effects of testosterone on resistance to coccidia, which is a common parasite of house finches. Free-living males in better condition had higher testosterone levels and lower corticosterone levels than free-living males in poor condition. In our captive experiment, increased testosterone accelerated the rate of coccidial infection as compared with sham-implanted or gonadectomized males. Although the differences were not significant, free-living males infected with coccidia had lower levels of testosterone and higher levels of corticosterone than males that were not infected. Thus, experimentally elevating testosterone levels in captive males resulted in a higher percentage of infected males, while free-living males with coccidial infection had low testosterone levels. This apparent discrepancy between captive and free-living males in the association of testosterone and disease may be explained by the condition dependence of testosterone. These results suggest that the testosterone-dependent sexual traits reliably indicate male overall condition and health and, thus, females could benefit from assessing potential mates based on these traits.     

Maternal strategies in sable antelope,Hippotragus niger: Factors affecting variability in maternal retrieval of hiding calves

Maternal behavior of wild ungulates has long been considered relatively invariant, yet recent reports from both wild and captive populations indicate considerable variability. Maternal behavioral tactics associated with the “hider” developmental strategy were investigated in six mother-infant pairs of sable antelope, Hippotragus niger, at the National Zoological Park's Conservation and Research Center near Front Royal, Virginia. When a calf moved away from its mother to hide, the mother tended to be 10 or more body lengths away and facing away from the calf. The presence of maternal vocalizations and the mother's ability to orient to the calf's resting site prior to calf activity periods were dependent on the age of the calf and whether the calf was lying alone or with other calves. The presence of maternal vocalizations and the ability of a mother to orient toward her calf were negatively related, with the mother vocalizing only when her calf could not be located visually. Variability in maternal behavior when searching for hidden calves was best explained by differences in calf conspicuousness. A mother apparently remembered only the general area in which her calf was lying, and not the precise location. Comparison of this study with previous studies of captive sable antelope suggests that mother-infant interactions are strongly influenced by enclosure size and the availability of tall vegetation; therefore, behaviors of individuals observed in small captive enclosures lacking tall vegetation may not be representative of those in the wild. © 1996 Wiley-Liss, Inc.     

Social vocal communication in captive Pacific walruses Odobenus rosmarus divergens

Walrus are highly gregarious pinnipeds that can form herds of several hundreds or thousands of individuals when hauling out on ice or on land. They produce vocalisations in almost all social interactions, from aggressive vocalisations, contact calls involved in mother–calf bond to adult–adult communication to stereotyped courtship display during the mating season. The knowledge on walrus’ vocal behaviour and its perceptual abilities is limited due to the extreme difficulty of studying these animals in their natural environment. In the present study, we reported the results of a pilot experimental work on group/social vocal communication in captive Pacific Walruses (Odobenus rosmarus divergens). By analysing the main vocalisations produced by females and males during social interactions, we found some differences in their call characteristics compared to the Atlantic subspecies. In a second step, we experimentally demonstrated the abilities of females and mature males to discriminate between vocalizations of individuals from their own group and those of unknown individuals. In spite of the low sample size of animals, these findings on captive walruses improved knowledge of the cognitive abilities of this endemic Arctic species.     

Behavioral Development and Parental Investment in Captive Bongos (Tragelaphus eurycerus)

SYNOPSIS. The bongo is one of the least-studied of the Tragelaphini.In a study of five captive bongo calves, two males and threefemales, we measured several behaviors important to parentalinvestment theory (Clutton-Brock et al., 1982), in order todescribe their pattern in a rare species, and add to the databasepertaining to sex allocation theory. Variations in individualpatterns of maternal investment, such as suckling rate and boutlength, were measured and graphed over time, with sex of calf,and age and dominance of dam indicated. Instances of "thiefsuckling" by calves and juveniles were also described in termsof kinship among the animals involved. Only one measure of maternalinvestment was biased in favor of males, which had a somewhathigher birth weight than females. Other measures showed littlesex difference. Among these calves, maternal care appeared tovary more with dominance and age of the dam than with sex ofcalf. Data from these animals generally conform more closelyto those of Byers and Moodie (1990). They found little evidenceof sex-biased investment among pronghorn (Antilocapra americana)fawns, and postulated that many ungulates have such a high rateof development that further differential investment is impossible.Robust biological theories are supported by data obtained froma wide variety of species, many of which are impossible to studyclosely in the wild. Additional studies on captive populationsof sexually dimorphic species would contribute usefully to theaccumulation of data pertinent to parental investment theory.     

Male vocalizations convey information on kinship and inbreeding in a lekking bird

Kinship and inbreeding are two major components involved in sexual selection and mating system evolution. However, the mechanisms underlying recognition and discrimination of genetically related or inbred individuals remain unclear. We investigated whether kinship and inbreeding information is related to low‐frequency vocalizations, “booms,” produced by males during their courtship in the lekking houbara bustard (Chlamydotis undulata undulata). Based on a captive breeding program where the pedigree of all males is known, we investigated the similarity of booms’ acoustic parameters among captive males more or less individually inbred and therefore genetically related with each other. In the wild, we investigated the relationship between the spatial distribution of males within leks and the similarity of acoustic parameters of their booms. In the captive population, we found (a) a relationship between the individual inbreeding level of captive males and their vocalization parameters; (b) that kin share similar frequency and temporal characteristics of their vocalizations. In the wild, we found no evidence for spatial structuring of males based on their acoustic parameters, in agreement with previous genetic findings on the absence of kin association within houbara bustard leks. Overall, our results indicate that genetic information potentially related to both the identity and quality of males is contained in their vocalizations.     

Behavioral sex differences and activity patterns of captive humboldt penguins (Spheniscus humboldti)

Three female and two male captive Humboldt penguins (Spheniscus humboldti) were observed in an enclosed exhibit over a period of 10 months to examine behavioral sex differences and to establish whether captive Humboldt penguins exhibit behavioral activity patterns. There were no statistically significant differences between the behaviors of males and females in six categories: resting, self-maintenance, locomoting, lack of visibility, agonistic behaviors, or pair-directed behaviors. Although not statistically significant, the pair-directed activities of bowing and ecstatic displaying were found to have potential use for sexual identification. Females bowing to males accounted for 77% of the observed bows. Further, males were observed performing 68% of the observed ecstatic displays, while females performed only 32%. Four behavioral phases were defined: molting, proximity, nesting, and “other.” Statistically significant behavioral differences occurred between the four phases for all ethogram behaviors with the exception of agonistic and pair-directed behaviors. Although housed under natural daylight and in an exhibit simulating their habitat in the wild, the captive birds failed to demonstrate a breeding season but bred throughout the study. However, this may have been influenced by one or more of the following factors: a ready supply of food; an air-filtered, temperature-controlled atmosphere; and the presence of an adequate number of nesting sites.     

Penetration of zona-free hamster ova by Siberian tiger sperm

Sperm from the electroejaculate of captive Siberian tigers (Panthera tigris altaica) penetrated zona pellucida-free hamster ova in vitro, evidenced by a decondensation reaction. This assay, when used in conjunction with semen analysis, may be useful in assessing the fertility potential of males of this and other related felids. Such information is an important step in developing successful long-term management strategies for captive and wild populations of this severely endangered species.     

Multiple paternity in viviparous kelp rockfish, <Emphasis Type="Italic">Sebastes atrovirens</Emphasis>

Analysis of multilocus microsatellite genotypes revealed multiple paternity for all of the seven viable broods of larvae produced by kelp rockfish, Sebastes atrovirens (Jordan and Gilbert 1880), held jointly in a large aquarium tank (n = eight females and eight males). Only two of the eight experimental males were identified as fathers, and alleles not found in any of the captive males were present in all seven broods, demonstrating paternity by wild males external to the experiment. Thus, all of the females mated with one or more males prior to capture, confirming that female kelp rockfish are capable of storing sperm and controlling the overall timing of egg fertilization. These results highlight the potential for a paternal influence on larval quality through female mate choice and sperm competition.     

Housing with Females Increases Testosterone and Cortisol Levels in Captive Groups of Black-Handed Spider Monkeys (Ateles geoffroyi)

The black‐handed spider monkey (Ateles geoffroyi) is a seasonal reproducer that requires a seclusiveness to copulate and has a fusion–fission social system. These features impose important restrictions to achieve reproduction of captive animals. We investigated if group composition in captive spider monkeys has any endocrine effects. We compared testosterone and cortisol concentrations during the mating season in all‐male and multifemale–multimale groups to study if the former condition impairs reproductive potential and increases stress. Concentrations of testosterone and cortisol of males living with females were higher than those of all‐male groups. In the multifemale–multimale condition, dominant males had the highest levels of testosterone, while the youngest males showed the highest concentrations of cortisol. Results show that males adjust well to isosexual grouping, this being an appropriate condition to keep animals when controlled reproduction is sought. Zoo Biol 31:490;–497, 2012. © 2012 Wiley Periodicals, Inc.     

Sexual competition in a group of captive bonobos (Pan paniscus)

We describe the occurrence of sexual competition, expressed as harassment of sexual interactions in a captive group of bonobos. We monitored all aggressive and pestering interventions during sexual interactions of three captive adult females, one adolescent, and three adult males. The study period covered two complete menstrual cycles for each female, with continuous daily observations. There was relatively little overt sexual competition by the males, in analogy with other studies. Most male interventions occurred towards interactions with the alfa female. The alfa female performed the most intense and the highest number of interventions towards the sexual interactions of the other females. The data provide evidence for female intra-sexual competition in this female dominant species.     

Breeding program for the lesser kudu (Tragelaphus imberbis) in North America

The lesser kudu (Tragelaphus imberbis) has been kept in North American zoological parks since 1930 but has never been a common species in collections. In 1987 this population totaled 28 animals: 15 males and 13 females. A pedigree evaluation in 1987 of the existing population indicated that eight effective founders and one potential founder were represented in the North American herd. Three new potential founders from European captive populations were added to the population in 1987 to increase the number of existing founder lines to 12 animals. As this species is not endangered or threatened in its native habitat, it is not a high priority to qualify for designation as an SSP species. Because of this, the institutions holding lesser kudu in North America decided to join informally and draft a breeding program to better manage this small captive population. This program was designed to minimize inbreeding and equalize genetic representation of founder animals to maximize genetic diversity. It requires a shift in management philosophy to establish stable groups of breeding females at participating institutions while rotating appropriate breeder males through these herds in a controlled manner to ensure minimization of inbreeding and maximization of genetic diversity. It is hoped that this program can serve as a model for the management of other small captive populations of non-SSP species.     

Fertility assessment of cheetah males with poor quality semen

Reports on semen quality of the cheetah (Acinonyx jubatus) indicate that high percentages of abnormal morphs and sperm concentrations, 10 times lower than in domestic cats, are found in all populations. These characteristics are believed to result from unusual genetic homozygosity, hypothesized to have been caused by passage of the species through one or more population bottlenecks during its recent history. In a sample of 12 captive-living males, we found semen characteristics to be equal or inferior to those previously reported for males living in other captive facilities. Ten of these males (83.3%) nevertheless produced pregnancies. Seventeen of 19 pregnancies resulted from matings during a single estrus. This examination of the reproductive potential of males having comparatively inferior ejaculate quality supports the suggestion that husbandry programs may be more significant than physiological impairment in causing the low birth rates of captive cheetahs. These results also have implications for ascertaining fertility thresholds in mammalian populations undergoing increased levels of inbreeding as a consequence of habitat deterioration. © 1993 Wiley-Liss, Inc.     

DEVELOPMENT OF DISPLAY BEHAVIOR IN YOUNG CAPTIVE BEARDED SEALS

In this study of the ontogeny of vocal behavior in captive bearded seals, Erignathus barbatus , (three males and three females), only males exhibited vocal displays. The onset of display behavior coincided with sexual maturity. Males exhibited three types of dive displays associated with the performance of vocalizations. Vocalizing individuals were frequently attended by another male that maintained passive muzzle contact with the vocalizing male. These interactions were non-aggressive and might play a role in the establishment of a social hierarchy or they might allow the attendee to obtain "near-field" vocal information from the displaying male. Captive males' vocalizations resembled those of males in the wild. However, display dives were shorter, and fewer vocalization types were documented among the captive males compared to bearded seals in the wild. The capacity of the captive males for producing well-formed, long calls with large frequency changes was also significantly less than for wild males. These capacities will likely develop further as the males grow older. Individual capacity for vocal production appears to develop gradually, showing plasticity in form development over time.     

The Strength of Species Recognition in Captive Female Zebra Finches (Taeniopygia guttata): A Comparison Across Estrildid Heterospecifics

Conspecific recognition is essential for sexually reproducing species. Captive zebra finches ( Taeniopygia guttata ) are a model system in which the behavioural, ontogenetic and neurobiological bases of own-species (conspecific) recognition have been studied in detail. To assess the potential role of phylogeographic effects on species recognition, we examined the spatial preferences of unmated captive-bred female zebra finches between unfamiliar captive males of conspecific and estrildid heterospecific male stimuli. In accordance with prior studies using domesticated Bengalese finches ( Lonchura striata vars. domestica ), we found significant spatial and behavioural preference for conspecific males by female zebra finches, irrespective of heterospecific male phylogeographic origin mating status, or individual behaviour. This result has ramifications for the interpretation of social and mate preferences in this model species as it implies a consistency of species discrimination by captive female zebra finches.     

Spatial Association in a Highly Inbred Ungulate Population: Evidence of Fine-Scale Kin Recognition

We present the first evidence of fine-scale kin recognition, based on a continuous measure of relatedness, in ungulates. The spatial association between herdmates of a captive population of aoudad ( Ammotragus lervia ), where all the individuals are related, is analysed during resting time. Our goal was to estimate which factors influence individuals' associations. The study population is highly inbred, although it does not show serious deleterious effects caused by consanguinity. It comprises a single captive herd, reproducing freely and in good conditions for more than 10 yr. It emerges that kin, measured as the coefficient of relationship between two given herdmates, is the main factor determining the spatial association (e.g. average distance) of male–male and female–female dyads, as more-related individuals tend to rest closer to each other than less-related ones. As for male–female dyads, individuals of a similar age tend to stay closer. To rule out any familiarity confounding effects, individuals' cohabitation time in the herd was added as a random factor in the analyses. Concerning the type of dyad, mother–calf dyads are characterized by higher proximity than others, particularly during the suckling period, whereas males tend to stay closer to each other than females or male–female dyads, being also more kin-related. Female social rank does not influence spatial association between herdmates. These results are related to group composition of the species in the wild, which are characterized by intense mother–calf bonds and all-male groups that are probably kin-related. It is seen that adult male–female associations are not related to kinship, but to age similarity, which is in accord with the assumption that main family groups in the wild are formed by matrilineal lines, whereas males are the dispersing sex.     

Serum prolactin and testosterone levels in captive and wild brown kiwi (Apteryx mantelli) during the prebreeding,breeding, and incubation periods

In brown kiwi (Apteryx mantelli), the male is the primary incubator, a trait that is relatively rare among birds. The maintenance of avian incubation behavior is controlled by the protein hormone prolactin (PRL). Although steroid hormone concentrations in both wild and captive kiwi have previously been reported, this study is the first to report levels of PRL in captive and wild male and female kiwi through the prebreeding and breeding seasons, and to directly compare testosterone (T) concentrations between captive and wild males during the breeding and incubation periods. Female PRL concentrations increased at the time of oviposition, whereas male PRL concentrations rose gradually between the prebreeding and incubation periods. Although males are considered the main incubator, an increase in PRL levels could help females maintain behaviors such as nest guarding, or to take over incubation the event of mate loss. A gradual increase in PRL allows the male to be ready for incubation during the long breeding season. Interestingly, T concentrations in captive males did not decrease during incubation and was significantly higher than in wild males. Continual elevated T could have an impact on sperm production through negative feedback, thereby contributing to the low egg fertility seen in captive kiwi. Therefore, determining the underlying reason for the differences in hormone levels could be significant, if not vital, for improving the success of captive kiwi breeding programs.     

Social structures in Pan paniscus: testing the female bonding hypothesis

Based on previous research in captivity, bonobos, Pan paniscus, have been called a female-bonded species. However, genetic and behavioural data indicate that wild females migrate. Bonding between these unrelated females would then be in contradiction with socio-ecological models. It has been argued that female bonding has been overemphasized in captive bonobos. We examine patterns of proximity, grooming and support behaviour in six well established captive groups of bonobos. We find that female bonding was not a typical characteristic of all captive bonobo groups. In only two groups there was a trend for females to prefer proximity with other females over association with males. We found no evidence that following or grooming between females was more frequent than between males and unrelated females or between males. Only in coalitions, females supported each other more than male–female or male–male dyads. We also investigated five mother–son pairs. Grooming was more frequent among mothers and sons than in any other dyad, but sons did not groom their mothers more than males groomed unrelated females. Mothers groomed their sons, or provided more support to them than females groomed or supported unrelated males. Thus, while bonds between females were clearly present, intersexual relations between males and either unrelated females or their mothers are of more, or equal importance.