BREEDING BIOLOGY OF SOUTHERN ELEPHANT SEALS IN PATAGONIA

Abstract: Elephant seals breed in Patagonia (Península Valdés, Argentina) from late August to early November, reaching peak numbers during the first week in October. Observations of this population over the past ten years yielded similar results. Eighty percent of the pups were born by 2 October. Most (96%) of 663 females marked during three breeding seasons gave birth to a pup. Females stayed on land a mean of 28 d, gave birth 6 d after arrival, nursed their pups for 22 d, and copulated a mean of 2.5 times 20 d after parturition and 2 d before departure. Copulations peaked during the third week in October. Males spent 57–80 d on land fasting and defending harems of up to 134 females (median 11–13 females, depending on year). Most (96%) marked females that gave birth ( n = 636) also weaned their pups successfully. Pup sex ratio was unity. Harems were smaller and breeding occurred about three weeks earlier in Patagonia than in other colonies. Thermal conditions, day length and food availability may explain clines in the timing of breeding events between populations, Other parameters of the breeding season for the expanding Patagonia colony are similar to those for declining southern elephant seal populations elsewhere.     

Pouch young removal and return to oestrus in wild southern hairy-nosed wombats (Lasiorhinus latifrons)

The southern hairy-nosed wombat (Lasiorhinus latifrons) is a seasonal breeding, burrowing marsupial adapted to a semi-arid environment and the closest relative of the endangered northern hairy-nosed wombat (Lasiorhinus krefftii). Females typically give birth to one to two young every 3 years with young weaned at 360-400 days. This study examined the occurrence of polyoestry in a wild population of southern hairy-nosed wombats, and in particular the ability of this species to produce additional offspring in the same breeding season if a young was prematurely lost or removed. Pouch young were removed during the breeding seasons of 1996/1997 and 2003. No females from the 1996 (n=3)/1997 (n=3) group gave birth to a second pouch young in the same breeding season. However, two females in this group gave birth to young the following season. In contrast, all the 2003 group of females (n=6) produced a second offspring in the same breeding season after removal of pouch young (RPY). The reason for the different response to RPY between the two groups is unknown. These studies confirm that southern hairy-nosed wombats are polyoestrus in the wild and are capable of producing more than one offspring in a single breeding season. Females that failed to return to oestrus in the breeding season that pouch young were removed bred again in the following season. Rapid replacement of southern hairy-nosed wombat pouch young in the same breeding season as RPY suggests that this procedure, linked to either hand-rearing or interspecific cross-fostering, should be seriously considered as a priority conservation action to increase the population size of the critically endangered sister species, the northern hairy-nosed wombat.     

藏酋猴社群雌体的性行为模式

猕猴属中大部分种类的繁殖类型可划分为季节性繁殖和非季节性繁殖两大类型。但是藏酋猴全年均有交配行为发生, 而产仔仅在1～8月间, 其类型属特殊的非季节性交配-季节性产仔繁殖类型。藏酋猴雌性在妊娠后选择的交配对象主要是高序位的雄性, 但非妊娠雌性则主要选择低序位雄性。妊娠后的雌性交配频率低于非妊娠雌性, 同时它们与成年雄性间理毛行为的发生频率亦低, 反之受到成年雄性攻击的频率却高。     

Effects of maternal age and condition on parturition and the perinatal period of Antarctic fur seals

The effect of maternal age and condition on the date of parturition and the duration of the perinatal period of Antarctic fur seals at Bird Island, South Georgia, were investigated over three consecutive breeding seasons. Females rear young during a four-month lactation period in a highly seasonal but predictable environment. Although females may first pup at three years of age, they did not attain full adult size until six years of age; older females (≥ 6 years) tended to be heavier, longer, and in better condition than younger females (3–5 years). Older females returned to breeding beaches earlier and could occupy the most suitable pupping sites, and gave birth when densities of animals on the beaches were low (i.e. more favourable for pup survival). Females that arrived earlier were able to remain ashore longer with their pups prior to departing on their first foraging trips but this was unrelated to either maternal age or condition. Younger females returned later in the pupping season, possibly as a result of late implantation due to smaller energy reserves than older and larger females. In 1990 all females arrived late, were in poorer condition, gave birth to lighter pups, and had shorter perinatal periods. This suggests that not only was implantation late but that females returned to an area of low food availability prior to parturition.     

THE EFFECT OF BIRTH DATE ON FITNESS OF FEMALE DWARF PERCH,MICROMETRUS MINIMUS (PERCIFORMES: EMBIOTOCIDAE)

Lifetime reproductive success may vary considerably with birth date. I measured phenotypic selection on female birth date in a viviparous teleost fish (Embiotocidae: Micrometrus minimus) by sampling birth-date cohorts over time in Tomales Bay, California. Four episodes of selection were measured: survival from birth to first reproduction, reproductive success in the first breeding season, survival to second reproduction, and reproductive success in the second season. Birth date had a significant impact on fitness in the first two episodes. Early born females were more successful in their first breeding season than late born females (directional selection on birth date), but early born females were less likely to survive the period between birth and first reproduction, relative to females born in the middle of the season (stabilizing selection on birth date). The final two episodes of selection had no detectable effect on birth date. Because of the relationship between birth date and survival in the first year, overall selection on female birth date was stabilizing.     

Reproductive Strategies in Lemur catta: Balance Among Sending,Receiving, and Countermarking Scent Signals

Our goal is to go deep into behavioral olfactory strategies possibly used by ring-tailed lemurs in reproductive competition and to shed some light on the function of female scent marks deposited outside the breeding season. We followed 16 captive adults at the Pistoia Zoo (Tuscany, Italy) for > 1,500 h from May 1997 to March 1999. Male direct and indirect olfactory investigation on females showed complementary distributions, the former peaking during the breeding and the latter during the birth season. Males are thus able to monitor female reproductive conditions throughout the whole year. During the birth season there was an increase of female genital marking. The olfactory advertisement probably guarantees that the extremely brief estrus does not remain unnoticed and allows male intrasexual competition a long period to operate. Male indirect olfactory monitoring and countermarking on female signals peaked during the birth season, which suggests that male intrasexual competition is achieved both by getting female chemical messages and by concealing them from other males. Female countermarking on other female genital marks peaked during the breeding season. High-ranking females had higher frequencies of countermarking than those of low-ranking females, which suggests that the advantage of obliterating scent signals of other females is greater than the disadvantage of revealing one's own reproductive condition.     

Reproductive parameters of female Japanese macaques: Thirty years data from the arashiyama troops,Japan

Over a 30-year period from 1954 to 1983, 975 live births were recorded for Japanese macaque females at the Iwatayama Monkey Park, Arashiyama, Japan. Excluding unknown birth dates, primiparous mothers gave birth to 185 infants (182 cases with age of mother known) and multiparous mothers gave birth to 723 infants (603 cases with age of mother known). The peak month of birth was May with 52.3% of the total births occurring during the period. Multiparous females who had not given birth the previous year did so earlier than multiparous females who had given birth the previous year and also earlier than primiparous females. Among the females who had given birth the previous year, females whose infant had died gave birth earlier than females who had reared an infant the previous year. The offspring sex ratio (1:0.97) was not significantly different from 1:1, and revealed no consistent association with mother's age. Age-fecundity exhibited a humped curve. The annual birth rate was low at the age of 4 years but increased thereafter, ranging between 46.7% and 69.0%, at between 5 and 19 years of age, but again decreased for females between 20 and 25 years of age. Some old females displayed clear reproductive senescence. The infant mortality within the first year of age was quite low (10.3%) and the neonatal (less than 1 month old) mortality rate accounted for 49.0% of all infant deaths. There was no significant difference between the mortality rates of male and female infants. A female's rank-class had no apparent effect on the annual birth rate, infant mortality, and offspring sex ratio. These long-term data are compared with those from other primate populations.     

ANNUAL REPRODUCTIVE CYCLE OF THE FEMALE HAWAIIAN MONK SEAL (MONACHUS SCHAUINSLANDI)

Abstract: The annual reproductive cycle is described for the adult female Hawaiian monk seal ( Monachus schauinslandi ) from data collected at Laysan Island (1982–1991) and Lisianski Island (1982–1983) in the Northwestern Hawaiian Islands. Pupping, lactation, weaning, and molting were directly observed, while mating was rarely observed and was, therefore, inferred from the occurrence of mounting injuries and from adult male and female association patterns. Pooled birth rates during the study period were 0.544 for all adult-sized females and 0.675 for females parous in earlier years. For parturient females, pupping peaked in late March and early April, weaning in May, mounting injuries in May and June, and molting in July. For non-parturient females, the median mounting injury and molting dates occurred 17 and 28 days earlier, respectively. Pupping date set the timing of subsequent events in the annual cycle, but the timing of those events was adjusted by loss of the pup or poor physical condition of the female. Individual pupping patterns varied widely. The mean interval for births in consecutive years was 381 days; females that pupped in consecutive years gave birth later each season. Conversely, females who skipped a year or more gave birth earlier their next pupping season.     

Differences in fertility and suckling patterns between primiparous and multiparous rhesus mothers (Macaca mulatta)

Primiparous females gave birth around the same time as multiparous nonlactating females, and earlier than did multiparous lactating females. No differences in birth sex ratio were found between primiparous and multiparous females. During the breeding season following birth, primiparous mothers returned to oestrus later than did multiparous mothers, and while few primiparous mothers conceived successfully during that season, most multiparous mothers did. Primiparous females suckled their infants more frequently than did multiparous females at all ages; infants of primiparous females also made more nipple contacts per bout, and had shorter sucking bouts. When mothers came into oestrus, suckling frequency drastically increased for primiparous females, but not for multiparous females, magnifying the differences between the two groups. After the first oestrus, suckling frequency declined for all mothers, but multiparous mothers had consistently lower suckling frequencies than did primiparous mothers. The high suckling frequency, and numerous nipple contacts per bout, found among primiparous mothers are likely to be related to the low reproductive chances that these females faced during the breeding season. Multiparous mothers seemed to compensate for their low suckling frequency by lengthening the suckling bouts, and this suckling pattern did not hinder their reproduction. It is argued that primiparous mothers might have to suckle their infants more frequently because they can only produce milk at slow rates, being in this way forced into a reproductively inhibiting suckling pattern. However, the delay in subsequent reproduction could be ultimately advantageous for primiparous mothers if it enhanced infant survival, and allowed the mothers to regain physical condition before reproducing again.     

Photomanipulation of sexual maturation and breeding cycle of the steppe polecat (Mustela eversmanni) and other techniques for more rapid propagation of the species

Twenty steppe polecats were divided into 2 groups, each consisting of 4 males and 6 females, and subjected to either a natural photoperiod (controls) or alternating periods of short (8 h light/16 hr dark for 8-9 weeks) and long days (16 h light/8 h dark for 16-20 weeks). The experimental photoperiod significantly accelerated sexual maturation in both sexes, with males developing maximal testis size within 57 days and females breeding after an average of 52 days exposure to 16L/8D. Males in the experimental group completed 2 1/2 testicular cycles and participated in mating during 3 successive breeding seasons during the 18 month period whereas males in the control group completed a single testicular cycle and only had an opportunity to mate during a single breeding season. Females in the experimental group produced 3 litters whereas females in the control group only gave birth to a single litter. Litter size averaged 6.9 +/- 2.0 (n = 23) and did not significantly differ with age, parity, or treatment. Pseudopregnant females returned to estrus within 12 days after the expected date of parturition, were bred, and gave birth to kits. Polecats which were subjected to the experimental photoperiods completed more molting cycles and underwent more photoperiod-induced changes in body weight than those in the control group. Death or removal of kits within 8 days after birth resulted in 12/12 females returning to estrus within 6-26 days. Eleven of these females were remated and gave birth to kits. Eight domestic ferrets readily accepted neonatal polecat kits and 5 successfully reared kits, although kit survival was quite poor.(ABSTRACT TRUNCATED AT 250 WORDS)     

Testing the reproductive and somatic trade‐off in female Columbian ground squirrels

Energetic trade‐offs in resource allocation form the basis of life‐history theory, which predicts that reproductive allocation in a given season should negatively affect future reproduction or individual survival. We examined how allocation of resources differed between successful and unsuccessful breeding female Columbian ground squirrels to discern any effects of resource allocation on reproductive and somatic efforts. We compared the survival rates, subsequent reprodction, and mass gain of successful breeders (females that successfully weaned young) and unsuccessful breeders (females that failed to give birth or wean young) and investigated “carryover” effects to the next year. Starting capital was an important factor influencing whether successful reproduction was initiated or not, as females with the lowest spring emergence masses did not give birth to a litter in that year. Females that were successful and unsuccessful at breeding in one year, however, were equally likely to be successful breeders in the next year and at very similar litter sizes. Although successful and unsuccessful breeding females showed no difference in over winter survival, females that failed to wean a litter gained additional mass during the season when they failed. The next year, those females had increased energy “capital” in the spring, leading to larger litter sizes. Columbian ground squirrels appear to act as income breeders that also rely on stored capital to increase their propensity for future reproduction. Failed breeders in one year “prepare” for future reproduction by accumulating additional mass, which is “carried over” to the subsequent reproductive season.     

Birthdate, mass and survival in mountain goat kids: effects of maternal characteristics and forage quality

In temperate environments, early-born ungulates may enjoy a longer growth period before winter, and so attain a higher body mass and an increased probability of survival compared to late-born ones. We assessed the effects of maternal characteristics, forage quality and population density on kid birthdate, mass and survival in a population of marked mountain goats (Oreamnos americanus) in Alberta. The duration and timing of the birth season were similar in all years. Births were highly synchronised: 80% of kids were born within 2 weeks of the first birth. Maternal age, maternal social rank and density did not affect kid birthdate or mass. Previous breeding experience was not related to kid birthdate, but kids born to pluriparous mothers were heavier during summer than kids born to primiparous mothers. Male and female kids had similar mass and accumulated mass linearly during summer. Early-born kids were heavier than late-born kids. Faecal crude protein (FCP) in late spring and maternal mass were positively related to kid mass. Survival to weaning appeared higher for males (90%) than for females (78%), but survival to 1 year was 65% for both sexes. FCP in late spring, density, birthdate and mass did not affect kid survival to weaning in either sex. Survival to 1 year increased with FCP in late spring for females, but not for males. Survival to 1 year was independent of birthdate for both sexes, but heavy females survived better than light ones. Multiple logistic regression revealed a positive effect of mass on survival to 1 year when the sexes were pooled. Our results suggest that mountain goats are constrained to give birth in a short birth season synchronised with forage productivity.     

Timing of births and juvenile mortality in the South American fur seal in Peru

In most species, synchronous, seasonal reproduction is usually associated with higher offspring survival in animals giving birth around the peak, relative to those breeding at the extremes of the reproductive season. In contrast, in the South American fur seal ( Arctocephalus australis ) at Punta San Juan, Peru, females pupping around the peak of births had a greater probability of losing their pups and/or tended to lose them at an earlier age than females breeding early or late in the season. However, the timing of breeding in this population varies little between years and is consistently synchronous. Individual females maintained their relative breeding times in consecutive years, regardless of whether or not they lost their pup the previous year. Thus, pup mortality seems to have no effect on the timing of reproduction in this population.
High breeding densities and the consequent high pup mortality in the S. American fur seal in Peru may have resulted from intense poaching outside protected areas and are of recent origin. The reproductive synchrony in this population could have originally evolved as a response to seasonal variations in food availability and weather conditions, differences in female or pup body condition, predation pressure, sexual selection and/or harassment avoidance, but at the present high density levels has become maladaptive.     

海南岛南湾半岛野生猕猴的繁殖研究

1981-1985年,在海南岛南湾半岛开展了对野生猕猴种群繁殖的研究。猕猴的发情交配期为11月至次年3月,产仔期为4-8月,怀孕期约177天。3年中,有70%的性成熟母猴每年产1胎,其它的产2胎或1胎。在连续两年中产仔间隔294-441天,平均362±16天,自1978年以来,年均繁殖率为53.8-100%,平均77.8±13.85%。雄性成熟年龄为3-4岁;约38%的雌性在3.5岁时开始怀孕,4岁产仔。低等级的雌性生育较少,雄性猴离群,无任何雄性终身在群内称王,这些都可避免种群衰退,利于种群生长和发展的极好生物学对策。     

Brief report: Outbreak of severe aggression in captive Macaca mulatta

An outbreak of severe aggression occurred among females in a rhesus macaque breeding group at the California Primate Research Center four years after the group was established. During the breeding season in which this occurred, the incidence of injured females in other breeding groups at the Primate Center was significantly higher than in the previous year. This breeding season was the first in which a large number of females reached sexual maturity. The group in which the most severe aggression occurred contained the largest number and proportion of maturing females. Evidence suggests that the simultaneous maturation of a large cohort of adolescent females may be associated with increased levels of aggression, and that this aggression may be intensified by certain aspects of captivity.     

Mass change, environmental variability and female fertility in wild Propithecus verreauxi

Accurate estimates of mass and size are important in a wide range of research questions in population and evolutionary biology, and yet such data are still rare for wild primates. This study presents detailed longitudinal data from a large population of wild indriids, and demonstrates links between fluctuations in body mass, environmental cycles, and reproduction. Understanding these links is a necessary step toward explaining the function and evolution of distinctive features of lemur biology and behavior.During the first 12 years of an ongoing study of the sifaka, Propithecus verreauxi verreauxi, at Beza Mahafaly in southwest Madagascar, 320 animals were captured and weighed throughout the year. Adult males and females exhibit seasonal cycles of mass loss, with females losing significantly more mass than males. In 2 drought years this pattern was especially pronounced. Compared to lighter females, females who were heavier at the time of the mating season were more likely to give birth in the following birth season. By showing (1) seasonally greater mass loss in reproductive females compared to males, particularly in drought years, (2) a close link between female mass and fertility, and (3) an uncoupling of the periods of highest body mass and of gestation and lactation, these results suggest that energy acquisition and storage are critically important in the life history strategies of female sifaka, and that "capital breeding" may be a feature of sifaka reproductive strategies.     

Annual productivity and individual female reproductive success in a Great Bustard Otis tarda population

The reproductive success of Great Bustards Otis tarda in north-western Spain was studied between 1987 and 1998, both at the population ( c . 700 adult females breeding in our study area) and the individual level (sample of 32 marked females). Overall productivity was low, with a population mean of only 0.14 chicks reared per adult female, and an average breeding success of 0.15 chicks per year in the sample of marked females, but interannual variability was high (0.04–0.29). Population productivity was positively correlated with winter (October–March) precipitation prior to each breeding season, and negatively correlated with the number of days of rain during the hatching period. High annual productivity resulted from a high proportion of females rearing two chicks. Reproductive success was higher in females older than 6 years than in younger birds. The proportion of females in the marked sample that failed in breeding after having bred successfully the previous season was significantly higher than the proportion of those that did not. Finally, females with a higher than average breeding success tended to breed successfully in years of both low and high population productivity, whereas those with lower than average breeding success did so only in years of high productivity.     

Seasonal and diurnal variation in vocal behaviour of the South Island robin

Abstract

The proportion of time spent by South Island robins (Petroica australis australis) of different sex, age, and status giving full song, subsong, and downscales, on a monthly and diurnal basis, is described. Females never gave full song. Males did so throughout the year, but least while moulting. Since bachelors sang significantly more than paired males, song probably functioned largely to attract females. Breeding males sang most during the pre-laying stage. From January to April adult males sang significantly more than immature males, but from May to July the reverse was true. Robins sang mainly in the early morning. Robins generally spent less than 0.5% of time during any stage of the breeding cycle giving sub-song. Outside the breeding season, males spent significantly more time giving sub-song than females, and adult males sang more than immature males. Robins in all categories gave more sub-song during the moult than afterwards. The diurnal pattern of sub-song production was bimodal. About half the downscales were followed by no obvious action from the caller or response from other robins, nor were the calls preceded by an obvious event. About 25% of the downscales were associated with interactions between members of a pair; the remainder were associated with territorial defence. Downscales probably served to maintain contact between members of a pair and to advertise possession of territory. These calls were heard rarely in the breeding season, and most frequently in April. Males gave downscales more than females, but use of downscales by both sexes was evenly distributed through the day.     

The onset of seasonal quiescence in the female Bennett's wallaby (Macropus rufogriseus rufogriseus)

The breeding season of the non-lactating Bennett's wallaby terminates when animals enter the state of seasonal quiescence. To examine this transition, pouch young were removed from females at intervals which were 3, 4 or 8 weeks (6, 11 and 8 animals respectively) after the winter solstice. Within 48 days, 3, 1 and 1 females gave birth respectively, indicating that these animals were not in seasonal quiescence when pouch young were removed. Those animals which did not give birth were either in seasonal quiescence or had undergone a non-pregnant cycle. To differentiate between the 2 possibilities, techniques which would ensure the detection of pregnant and non-pregnant cycles were assessed in 8 females during the breeding season. As has been previously reported for the wallaby, changes in peripheral progesterone concentrations and the vaginal smear occurred during pregnant and non-pregnant reproductive cycles. In addition, mating was detected by marking the male with a mixture of coloured crayon and paraffin wax. It was concluded that reproductive cycles in female wallabies could be monitored by collecting blood samples 2 times each week for progesterone determination and daily examination of females for mating marks. These techniques were then used to study the onset of seasonal quiescence in 9 females. All animals continued to show reproductive cycles after the winter solstice and it was not until 10 weeks after the winter solstice that all animals were in seasonal quiescence. This represents an increase in the duration of the breeding season over that previously reported for this species.     

Influence of daylength on the initiation of the breeding season of the marsupial possum, Trichosurus vulpecula

In Queensland, possums in the wild and in captivity first give birth during March and continue to give birth throughout the year until November. In this study the effect of short daylengths on the initiation of breeding activity was examined. One male and 4 female possums were transferred from an outside enclosure into a light control room (10 h light, 14 h dark) on 22 November. A control group of possums was housed in outside enclosures. The possums held in the light room gave birth 81.2 +/- 14.7 days (s.e.m.) after being placed in the short-day photoperiod. The control group gave birth 133.8 +/- 9.8 days after 22 November. This result suggests that photoperiod plays a role in the initiation of the breeding season of the brushtail possum.