Reproductive parameters of mandrills at the Tulsa Zoo

The genital swelling patterns and birth records of female mandrills housed at the Tulsa Zoo between 1979 and 1992 were examined to determine various reproductive parameters. Mean age at first adolescent genital swelling was 2.7 years (sd = .55), first adult swelling was 3.7 years (sd = .64), and first conception was 5.1 years (sd = 1.30). Genital swelling cycle duration averaged 39.6 days (n = 33 cycles), with the swelling phase averaging 19.5 days (n = 51 cycles). There was no interindividual difference in cycle length (F = 1.26, P = .31) or swelling duration (F = 0.65, P = .58), nor was there a difference in cycle length (F = 0.47, P = .50) or swelling duration (F = 1.27, P = .27) before and after first parturition. Duration of gestation was estimated to be 165.9 days (sd = 3.3; n = 17 pregnancies). Lactational anestrus averaged 10.1 months, whereas mean interbirth interval was 17.9 months (n = 11). There was a significant negative correlation between age of the mother and interbirth interval (r = ?;0.648, P = .03). Data presented in this report provide a comprehensive profile of reproductive parameters for zoo-housed mandrills, which may aid other facilities in the reproductive management of their captive groups. © 1995 Wiley-Liss, Inc.     

Life History and Reproductive Strategies of Khao Yai <Emphasis Type="Italic">Hylobates lar</Emphasis>: Implications for Social Evolution in Apes

Among primates, great apes have the most extended life histories and they also appear socially specialized because of their flexible association patterns and sociosexual relationships. Researchers have hypothesized that such subtle social commonalities in combination with a slow life pace lead to great apes advanced cognition. Small apes, in contrast to great apes, are commonly believed to be socially inflexible, and little comparative life history data exist for wild populations. We investigated how the small white-handed gibbon (Hylobates lar) fits into a great ape life history and sociality framework. We followed the life histories of adults in 12 groups over ca. 18 yr at Khao Yai National Park, Thailand. Results demonstrate that the life histories of white-handed gibbons closely resembled those of other apes. Mean female age at first reproduction was late (11.06 yr), and mean interbirth interval (41 ± 9.1 mo) and juvenile period (9.5 ± 1.8 yr) were long. Multimale grouping of 2 adult males and 1 female was a common alternative (21.2% groups) to the traditional hylobatid pair-living social organization in our population. Female sexual partnerships include a variety of polyandrous mating strategies for both pair-living females and females in multimale groups. From our long-term study a picture of social complexity materializes that resembles social complexities in other apes. In conclusion, we infer that gibbons share commonalities postulated to unite great apes based on similar life histories and very flexible social and sexual relationships.     

The reproductive biology of female Père David's deer (Elaphurus davidianus)

Data for this study came from breeding records of 27 Père David's (Elaphurus davidianus) hinds maintained in large pastures and from estrous records of four hand-reared nulliparous hinds. The mean estrous cycle length ranged from 17.5 to 19.6 days. Standing estrus resembled that of other cervids, except that a low, moaning vocalization was given in response to contact, and activity (as measured by pedometers) did not increase. Mean gestation length was 183.38 ± SD 6.11 days (n = 21), and nearly all females conceived in the second and third years. The median interbirth interval was 362 days. The median birth date was April 8, and 80% of the births occurred over a 9.5-week period. Multiparous hinds gave birth an average of 20.5 days earlier in the season than primiparous hinds. There was no dimorphism in birth weight. The results are discussed in light of comparative data for other species.     

Age-specific birth rate and lifetime reproductive success of chimpanzees at Bossou,Guinea

Preliminary calculations of the age-specific birth rate for wild female chimpanzees were based on demographic records from a long-term study at Bossou, Republic of Guinea. Primiparous age was 12-14 years. Birth rate for a female reached a peak of 0.333 a year at 20-23 years, and then decreased until menopause at more than 40 years of age. Mean birth rate for a female of more than 12 years was 0.197 a year. Mean interbirth interval was 4.6 years overall, but 5.1 years, if all cases in which the previous infant had died within its first three years were excluded. Infant survival rate for the first four years was 0.727 and that of juveniles (four to seven years) was 0.714; however, that of adolescents (eight to 11 years) was only 0.222. Some adolescents who disappeared from Bossou are thought to have migrated to adjacent habitats. From age-specific birth rate and survival rate, the lifetime reproductive success was calculated as only 0.74 offspring per female. This rose to 2.39 when adolescent survival rate was assumed to be the same as that of juveniles. This must be less than the minimum reproductive success required for continued survival of the population. The recent and continuing degradation of the environment will lead to the extermination of this species from the area in the near future. © 1994 Wiley-Liss, Inc.     

Patterns of reproduction in Malayan silvered leaf monkeys at the Bronx Zoo

Within phylogenetic limits reproductive characteristics of a given species may vary between populations in response to ecological and social factors. For instance, in environments where high quality nutrition is readily available, the onset and speed of reproduction are often accelerated. Other influencing factors might be maternal experience or the sex of the infant. Here we present data on reproductive characteristics for the silvered leaf monkey (Trachypithecus cristatus), a medium‐sized Asian colobine housed at the Wildlife Conservation Society's Bronx Zoo as a one‐male group. To place the species into an appropriate phylogenetic context, we limited our comparison to other colobine species. Demographic data span 21.4 years (October 1985 to March 2007) and derive from 30 adult females (128.0 female years). Detailed behavioral data stem from a 2.2 years study (November 2002 to January 2005; 734 days, 4,225 hr). As in other Asian colobines, receptive periods were short (mean=4.3 days, n=68). This is expected for one‐male groups where receptivity likely indicates, rather than conceals, ovulation. Gestation length was estimated based on a change in the pattern of sexual behavior (mean=194.6 days, n=7). It fell within the range reported for the taxon. Births occurred year round, at an early age (mean=2.9 years, n=8), at short intervals (mean=14.9 months, n=59) in combination with a short lactation (mean 12.1 months, n=9) likely due to the nearly unlimited availability of nutrition in this zoo setting. Primiparous females tended to have a longer first interbirth interval but infant survival rates were similar to multipara possibly due to the absence of predators. Maternal investment was independent of the infant's sex and birth sex ratio was even. Our results emphasize that when interpreted with caution, zoo populations yield realistic reproductive characteristics that can help fill the gap in our knowledge about colobine life history. Am. J. Primatol. 71:852–859, 2009. © 2009 Wiley‐Liss, Inc.     

Geographic Variations in Reproductive Parameters of the Starspotted Dogfish, Mustelus manazo, from Five Localities in Japan and in Taiwan

Geographic variations in reproductive parameters of Mustelus manazo from five localities, four in Japan (Aomori, Tokyo Bay, Maizuru, and Shimonoseki) and one in Taiwan, were investigated from November 1994 to June 1996. Differences in age and length at sexual maturity from Aomori to Taiwan were approximately 3 years and 300mm in TL, respectively, for both sexes. The sharks appeared to mature at a later age and to a larger size in the most northern population, Aomori, and to be faster and smaller in the southern population, Taiwan. Mating, ovulation and fertilization periods were generally during May and August in the four localities of Tokyo Bay, Maizuru, Shimonoseki, and Taiwan. In Aomori, males showed no clear monthly variation in gonad index, and females in Aomori had a protracted reproductive period. Females became pregnant every year in all localities, except Aomori. The Aomori population apparently has a different reproductive cycle. The Tokyo Bay population is distinctive regarding growth and sex ratios of embryos. In all localities, the number of embryos per litter increased relative to total length of mother. There was no geographic variation in reproductive parameters between Maizuru and Shimonoseki. The coast between these last two sampling areas is a continuous steep slope with similar environmental conditions, and mixing of the two populations may occur.     

Reproduction in wild female olive baboons

The purpose of this paper is to evaluate several factors that influence female reproduction in a large troop of wild olive baboons (Papio cynocephalus anubis) based on 4 consecutive years of demographic data. Interbirth intervals were significantly shorter for females whose infants died before their next conception than for females whose infants survived. High-ranking mothers of surviving infants had significantly shorter birth intervals than comparable low-ranking mothers, independent of maternal age. This occurred mainly because the interval from resumption of cycling to conception was significantly shorter for high-vs. low-ranking females. Dominance rank did not influence sex ratio at birth, infant survival in the first 2 years, or adult female mortality. Age was also significantly related to interbirth intervals, with older females having shorter intervals. Primiparous females had consistently longer reproductive intervals than did multiparous females, but this difference reached statistical significance only for females whose infants died before the next conception. Primiparous females also experienced significantly higher infant mortality. Data on body size and estrous cycle length indicated no differences between high- and low-ranking females. Nutritional and stress-related mechanisms that may underlie the reproductive advantages of high rank are discussed.     

Demographic parameters and life history of chimpanzees at Bossou, Guinea

Demographic parameters of wild chimpanzees at Bossou, Guinea, are presented and compared with those of other populations. The population size of Bossou chimpanzees has been stable over the last 26 years, except during two incidents of partial deforestation. The annual birth rate for a female (mean = 0.194, but 0.165 when the infant survived more than 4 years) and interbirth interval are not much different from those of other study sites. The primiparous age of Bossou chimpanzees, however, is far younger (mean = 10.9 years) than for all other known wild chimpanzee populations. The infant and juvenile survival rate is also the highest (female = 0.64, male = 0.52 for the first 8 years). As a result, the lifetime reproductive success of Bossou chimpanzees is estimated to be highest among long-term study sites. The rate of disappearance from Bossou dramatically increases during the adolescent stage, and most young chimpanzees disappear before or around maturation. Probably because the environmental capacity for chimpanzees at Bossou is at its limit, many young independent males, as well as females, have to disperse, though others may die. For chimpanzee alpha males of other populations, mature males may be needed as collaborators to defend resources. In the case of Bossou, however, a lack of adjacent groups, conspecific competitors, predators, and perhaps medium-sized mammals as prey for group hunting may eliminate this need of the alpha male for other males. The reasons why all males of other chimpanzee populations persist in being philopatric for life and maintain kin-related male bonds differing from most mammal species, including humans, are discussed.     

Reproduction in the slow loris (Nycticebus coucang)

The reproductive biology of the slow loris (Nycticebus coucang) is poorly documented because of infrequent captive breeding success and the absence of field studies of this species. Reproductive data were collected from a breeding colony of slow lorises held at the Duke University Primate Center for the past 10 years. Nineteen infants were born, with a sex ratio of 1:1 and a neonatal mortality rate of 15.8%. In all cases, litter size was one. Females born in the colony copulated for the first time between 18 and 24 months of age. A male that reached sexual maturity in the colony sired his first offspring at the age of 17 months. Estrous cycles ranged in duration from 29–45 days, with copulations usually occurring for 1 day of estrus. Gestation length averaged 192.2 days. Although a postpartum estrus was observed in three cases of infant death, no conceptions resulted. Lactation lasted approximately 6 months. A clear birth peak was observed, with 12 out of 19 births occurring in March, April, and May. The comparatively low basal metabolic rate of this species may account for the unusually low reproductive rate of the slow loris in comparison with other prosimian primates.     

The influence of persistent individual differences and age at maturity on effective population size

Ratios of effective populations size, N(e), to census population size, N, are used as a measure of genetic drift in populations. Several life-history parameters have been shown to affect these ratios, including mating system and age at sexual maturation. Using a stochastic matrix model, we examine how different levels of persistent individual differences in mating success among males may affect N(e)/N, and how this relates to generation time. Individual differences of this type are shown to cause a lower N(e)/N ratio than would be expected when mating is independent among seasons. Examining the way in which age at maturity affects N(e)/N, we find that both the direction and magnitude of the effect depends on the survival rate of juveniles in the population. In particular, when maturation is delayed, lowered juvenile survival causes higher levels of genetic drift. In addition, predicted shifts in N(e)/N with changing age at maturity are shown to be dependent on which of the commonly used definitions of census population size, N, is employed. Our results demonstrate that patterns of mating success, as well as juvenile survival probabilities, have substantial effects on rates of genetic drift.     

The Biology of the Nurse Shark,Ginglymostoma cirratum,Off the Florida East Coast and the Bahama Islands

The nurse shark is an extremely abundant shallow water species in Florida and the Caribbean, yet its biology is poorly known. Moreover, there is a great deal of misinformation about it in the literature. The maximum size and weight attained by the nurse shark have often been exaggerated. None of the specimens measured in this study exceeded 265cm TL and 114.5kg, and none of the specimens actually measured by other researchers exceeded 280cm. Females reach maturity at a length of 223–231cm, or at 86% of their maximum size. Males reach maturity between 214 and 214.6cm in length or at about 83% of their maximum size. Mating primarily occurs from mid-June to early July. The embryos are enclosed in sturdy egg capsules for the first 12–14 weeks of gestation. In a gravid female, the embryos are at different stages of development during the first four months of gestation. Embryos are lecithotrophic and there is no evidence of any supplemental mode of embryonic nourishment. Embryos measure 28–30.5cm at birth. The gestation period is estimated at about five to six months. Brood sizes are large, ranging from 21 to 50 young, with a median of 34 young. The reproductive cycle of the nurse shark consists of a five to six-month gestation period and a two-year ovarian cycle. Thus, the reproductive cycle is biennial and a female produces a brood every two years. The nurse shark is an opportunistic predator that consumes a wide range of small fishes, primarily grunts (Haemulidae).