Effects of cohort,sex, and birth date on body development of roe deer (Capreolus capreolus) fawns

We investigated the effects of the year of birth (cohort effect), sex and birth date on the variations observed in birth weight and postnatal growth rate in 209 newborn fawns marked during eight consecutive fawning seasons from a highly productive roe deer population under good nutritional conditions. Roe deer exhibited a fast body development with a birth weight of 1628 g and a postnatal growth rate of 139 g/day constant over the first 20 days of their life. As previously reported for dimorphic and polygynous ungulates, there was a marked cohort effect on the rate of body development. This variability was partly explained by climatic conditions during late gestation. When fewer than 5 days with rainfall over 5 mm occurred in April, fawns were heavier. High temperatures during April and during the winter could also be involved in fast body development of roe deer fawns. Sex of fawn did not affect roe deer growth pattern. This was expected on the basis of low sexual dimorphism in size and low polygyny level characteristic of roe deer. Lastly, the date of birth did not affect the body development of roe deer fawns. High constancy of mean birth dates and high synchrony of births observed in this population could account for this result.     

驯养林麝(Moschus berezovskii)的繁殖节律:分娩定时及同步化

于2013年3—10月在四川马尔康麝场开展,记录了178例驯养林麝(Moschus berezovskii)的分娩,分析了其分娩定时、同步化及关键影响因素。结果表明,马尔康麝场的驯养林麝分娩发生于5—7月间,分娩期长达66d,平均分娩时间为5月25日(17.60±0.98,n=178),分娩季节(75%的分娩完成时间)长22d(即5月7日至5月28日间)。马尔康林麝分娩的强季节性是对当地季节性水热条件和食物资源的适应。驯养林麝的分娩时间与其年龄的相关不显著(r=-0.121,P=0.1060.05),虽亚成体雌麝(2—3岁)的分娩时间(5月26日,18.81±1.47,n=75)有迟于成体麝((4—9岁)(5月24日,16.97±1.41,n=95)和老龄雌麝(≥10岁)(5月21日,13.63±2.24,n=8)的趋势,但差异未达显著水平(P0.05)。此外,麝场各饲养区内的雌麝分娩时间格局无显著差异(P0.05),泥地基底的改装圈舍内的雌麝分娩(5月22日,15.31±1.48,n=62)略早于砖地基底的原装圈舍雌麝分娩(5月26日,18.82±1.27,n=116),差异未达显著水平(P0.05)。     

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.     

Parturition date for a given female is highly repeatable within five roe deer populations

Births are highly synchronized among females in many mammal populations in temperate areas. Although laying date for a given female is also repeatable within populations of birds, limited evidence suggests low repeatability of parturition date for individual females in mammals, and between-population variability in repeatability has never, to our knowledge, been assessed. We quantified the repeatability of parturition date for individual females in five populations of roe deer, which we found to vary between 0.54 and 0.93. Each year, some females gave birth consistently earlier in the year, whereas others gave birth consistently later. In addition, all females followed the same lifetime trajectory for parturition date, giving birth progressively earlier as they aged. Giving birth early should allow mothers to increase offspring survival, although few females managed to do so. The marked repeatability of parturition date in roe deer females is the highest ever reported for a mammal, suggesting low phenotypic plasticity in this trait.     

Factors associated with birth rate and live birth rate in multi-male breeding groups of rhesus monkeys

Reproductive records of 284 female rhesus monkeys housed in six multimale corrals at the California Primate Research Center were examined for the birth seasons 1977–1982 to determine possible associations between the probability of birth or live birth and female age, parity, origin, parturition in the previous season, infant birth date, and infant birth date in previous season. Multiple logistic regression analysis was used to identify and quantitate the effects of factors on the probability of birth or live birth, while controlling for the possibly confounding effects of other factors in the model. Females who had infants early in the previous season were 2.5 times as likely to give birth as those who had infants late in the previous season. Females with two or three previous births were 2.1 times as likely to give birth, and those with four or five previous births were 6.7 times as likely to give birth as were females with no or one previous birth. Controlling for other factors (age, parity, and timing of birth in the previous season), corralborn females were 3.3 times as likely to give birth as either wild-caught or domestic-born monkeys not native to the corrals. Domestic-born females who were not corral natives were 0.3 times as likely to have live births as wild-caught females. Births late in the season were 1.8 times as likely to result in live infants as births early in the season.     

Long‐lived and heavier females give birth earlier in roe deer

In seasonal environments, parturition of most vertebrates generally occurs within a short time‐window each year. This synchrony is generally interpreted as being adaptive, as early born young survive better over the critical season than late born young. Among large herbivores, the factors involved in driving among‐ and within‐individual variation in parturition date are poorly understood. We explored this question by analyzing the relative importance of attributes linked to female quality (longevity, median adult body mass and cohort), time‐dependent attributes linked to female condition (reproductive success the previous year, relative annual body mass and offspring cohort (year)), and age in shaping observed variation in parturition date of roe deer. A measure of quality combining the effects of female longevity and median adult body mass accounted for 11% of the observed among‐individual variation in parturition date. Females of 2 yr old give birth 5 d later than older females. Our study demonstrates that high quality (heavy and long‐lived) females give birth earlier than low quality females. Temporally variable attributes linked to female condition, such as reproductive success in the previous year and relative annual body mass, had no detectable influence on parturition date. We conclude that parturition date, a crucial determinant of reproductive success, is shaped by attributes linked to female quality rather than by time‐dependent attributes linked to female condition in income breeders (individuals that rely on current resource intake rather than on accumulated body reserves to offset the increased energy requirements due to reproduction) such as roe deer.     

Metabolic cost of first reproduction in young female European roe deerCapreolus capreolus

In female roe deerCapreolus capreolus (Linnaeus, 1758), like in several deer species, first reproduction occurs before they have reached their full body size. This study quantifies, in young females, the energetic costs induced by the contemporaneously occurring events: growth and first reproduction. Resting metabolic rate and body mass were measured in young primiparous females from first mating to 4 months after parturition, and compared to values measured in fully-grown adult multiparous females. Throughout the 10-month period from mating to fawning, body mass increased in yearlings. Prior to the blastocyst implantation (month −5 before parturition) young females were lighter than adult females whereas after parturition they had the same body mass. Our results suggest that body growth was reinitiated during pregnancy in primiparous females. From mating to fawning, except in the first part of pregnancy, mass-specific metabolism was higher in primiparous females than in multiparous individuals indicating the occurrence of an additional cost due to growth in young females. The depressed level observed at the beginning of gestation could allow the resumption of growth at lower cost. Thus, the allocation of resources to both reproduction and growth was not detrimental to first reproduction in young female roe deer under experimental conditions withad lib feeding.     

Ecological cues, gestation length, and birth timing in African buffalo (Syncerus caffer)

We examined annual variation in the timing of conception andparturition in the African buffalo (Syncerus caffer) and thesynchrony of birth timing with resource cues, using 8 yearsof monthly birth, rainfall, and vegetation data, measured asNormalized Difference Vegetation Index (NDVI). Monthly birthshad the strongest significant correlations with NDVI and rainfalllevels 12 and 13 months in the past, respectively. In addition,the synchrony of current year births corresponds most stronglyto the synchrony of the previous year's NDVI distribution. Becausethe gestation period of buffalo has been estimated to be around11 months, these findings suggest that improved protein levels,occurring approximately a month after the first green flushof the wet season, are either a trigger for conception or conceptionhas evolved to be synchronous with correlated environmentalcues that ensure females enter a period of peak body conditionaround the time of conception and/or parturition. With a gestationperiod of approximately 340 days, parturition occurs to takeadvantage of the period when forage has its highest proteincontent. A comparative analysis of gestation periods withinthe subfamily Bovinae indicates that African buffalo have aprotracted gestation for their body size, which we suggest isan adaptation to their seasonal environment. We also found thatinterannual variation in the birth distribution suggests a degreeof plasticity in the date of conception, and variation in thenumber of calves born each year suggest further synchrony ata timescale longer than a single year.     

Environmentally cued parturition in a desert rattlesnake,Crotalus atrox

Embryonic development in animals is dynamically regulated by physiological, behavioural, and environmental factors (temperature, precipitation, humidity), which in turn influence the timing of birth or hatching. In the present study, we provide evidence that parturition in a large‐bodied North American pitviper, the western diamond‐backed rattlesnake (Crotalus atrox), is environmentally cued. Specifically, we tested the hypothesis of births coinciding with rainfall events during the second‐half of the monsoon season (late July to mid September) using randomization modelling. Twenty‐one adult females surgically implanted with radio‐transmitters were tracked for extended periods from 2001–2010. From 2003 to 2007, the 21 females gave birth to 38 litters, generating sufficient data to test our hypothesis. In all years, births were restricted to a 4‐week period from 5 August to 7 September, which spanned between 6 and 19 days (mean ± SD, 15 ± 5.2 days). Most births (92.1%) occurred in August. Births were significantly associated with rainfall events in 2007, although births in 2003 and 2005 occurred closer to rain events than randomly generated births for respective years. However, when birth events across all 5 years were pooled, the model indicated a significance difference in mean rain‐days versus random rain‐days. Hence, births occurred more closely to rain events than random days. Other variables associated with monsoon events (increases in cloud cover and humidity; changes in barometric pressure) were not measured but constitute potential cues. The present research is the first long‐term, individual‐based radio‐telemetric study of a snake species to investigate environmental cues related to parturition using procedures of randomization modelling. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 110 , 866–877.     

Coastal residence periods and reproductive timing in southern right whales, Eubalaena australis

The duration and timing of coastal residence of individually identified southern right whales at a principal aggregation area on the southern Australian coast differed markedly between females with calves and unaccompanied whales. The mean residence period of females that calved within the aggregation area was 70.9 days, with mean residence mid-points of 20 August in 1993 and 22 August in 1994. In contrast, unaccompanied adults remained resident for an average of only 20.4 days with mean residence mid-points of 27 July and 11 August in 1993 and 1994, respectively. Whales have been sighted at this aggregation area from mid May to late October (approx. 160 days), although the effective calving season (95-100% of calves born) lasted only 88 days in 1993 and 96 days in 1994. The mean birth date based on first sighting with neonatal calf, and corrected for sightability bias, was 15 July in 1993 and 17 July in 1994, with 100% of calves born before 31 August 1993 and 23 September 1994.
The time between birth and dispersal from the aggregation area, at or just prior to the commencement of the southward migration, was highly variable. Calves bom before the mean calving date averaged 80 days within the aggregation area, twice as long as those born after the mean (40 days). The large number of calves estimated to be less than 14 days old at first sighting, combined with the sighting of 26 pregnant females prior to parturition, suggests the majority of births occurred within, or very near to, the aggregation area.     

Reproductive Parameters of Wild Female Lagothrix lagotricha

I describe the reproductive patterns of female woolly monkeys (Lagothrix lagotricha) based on a 12-year study of one group of them at Macarena Ecological Investigations Center, Meta, Colombia. As in other atelin species—muriquis and spider monkeys—characterized by male philopatry, female woolly monkeys leave their natal groups. The age of emigration is ca. 6 years. Females probably begin to copulate with adult males soon after emigration, while their mean age of first parturition is 9 years. They frequently changed groups until they birthed. The average interbirth interval is 36.7 mo (n = 13). All births occurred between July and December (late wet season to early dry season). Copulation occurred throughout the year. However, they copulated more frequently in the estimated conception period from December to May (early dry season to early wet season) than in the birth season. The females had a period of sexual inactivity averaging <23.4 mo after parturition, followed by a period of sexual activity >7.2 mo until conception. The copulation period and copulation cycle or interval between copulation periods averaged 2.3 and 11.3 days calculated by a conventional method, or 3.1 and 14.7 days by a slightly modified method. The reproductive parameters of woolly monkeys are quite similar to those reported for other atelins in many respects, except the immigration process and age of first copulation.     

Timing of parturition in the rat: an analysis of successive births

To determine whether consecutive parturitions within individual rats are likely to occur around the same time of the 24h day, female rats mated prior to ovulation and maintained on a LD 12:12 photoperiod, were observed over either two or three parturitions. A subgroup of females was placed on constant light during the second gestation in order to determine the role of photoperiod in the temporal synchronization of consecutive births. The major findings were 1. individual females tended to give birth around the same time of the day on consecutive births so long as the photoperiod remained constant; 2. the small percentage of births occurring during darkness, the less-prevalent time of the photoperiod for birthing, were anomalous births for individual females; and 3. litter weight was a significant factor in predicting time of birth for females, but this effect interacted with photoperiod. These data elucidate the importance of knowing previous birth time, litter weight, and photoperiod on predicting the time of parturition in the rat.     

Length of postpartum anestrus in goats in subtropical Mexico: effect of season of parturition and duration of nursing

The aim of this study was to determine whether season of birth and length of nursing affected the duration of postpartum anestrus in Creole female goats maintained on a constant plane of nutrition in subtropical Mexico. Three experiments were conducted in the Laguna region in the State of Coahuila, Mexico (26 degrees N). In the first experiment, 34 goats gave birth in January; in the second, 31 females gave birth in May; and in the third, 22 goats kidded in October. At parturition, females were allocated to 1 of 3 groups based on body weight and date of parturition: kids were weaned at 2, 30 or 90 d according to their group. After weaning, females were milked manually once a day until the end of the study. All animals were kept in a shed and were fed alfalfa ad libitum and given 200 g of concentrate daily. Starting 1 wk after parturition, estrous behavior was detected twice daily using an apron-bearing male, and blood samples were obtained twice weekly to determine ovarian activity from the plasma progesterone levels. A strong effect of month of parturition was found on the duration of postpartum anestrus (P < 0.0001), which was longer in females kidding in January (about 200 d) than in those kidding in May (about 100 d) or October (about 50 d). A tendency for an interaction between season of parturition and length of nursing was observed in the length of anovulation (P < 0.07): for parturition in October, anestrus was longer when kids were weaned after 90 d than after 2 or 30 d (P < 0.01). Season of parturition also affected dates of reinitiation of ovulatory and estrous activity (P < 0.001). Proportions of normal, short and long cycles and of associations between estrous and ovulations were not influenced by season of parturition or the age of weaning. These data demonstrate that in subtropical latitudes, season of parturition can dramatically influence the duration of postpartum anestrus independently of the availability of food.     

Never too late? Consequences of late birthdate for mass and survival of bighorn lambs

In strongly seasonal environments, the timing of birth can have important fitness consequences. We investigated which factors affect parturition date and how birthdate interacts with sex, maternal characteristics and environmental variables to affect the growth and survival of bighorn sheep (Ovis canadensis) lambs in a marked population in Alberta. Over 14 years, the estimated birthdate of 216 lambs ranged from 21 May to 18 July. Parturition date was heritable and genetically correlated with maternal mass the previous fall. Weaning a lamb delayed parturition the following year by about 7 days. Birthdate did not affect summer growth rate, but late-born lambs were lighter in mid September (the approximate time of weaning) than early-born ones. Birthdate did not affect survival to weaning, but late birth decreased survival to 1 year for male lambs. Forage quality, measured by fecal crude protein, did not affect survival to 1 year. Once we accounted for lamb mass in mid September, birthdate no longer affected the probability of survival, suggesting that late birth decreased survival by shortening a lamb's growing season. Because there was no compensatory summer growth, late-born lambs were smaller than early-born ones at the onset of winter. Our data highlight the importance of birthdate on life history traits and suggest that resource scarcity had more severe consequences for juvenile males than for females.     

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.     

Factors Affecting Date of Implantation,Parturition, and Den Entry Estimated from Activity and Body Temperature in Free-Ranging Brown Bears

Knowledge of factors influencing the timing of reproduction is important for animal conservation and management. Brown bears (Ursus arctos) are able to vary the birth date of their cubs in response to their fat stores, but little information is available about the timing of implantation and parturition in free-ranging brown bears. Body temperature and activity of pregnant brown bears is higher during the gestation period than during the rest of hibernation and drops at parturition. We compared mean daily body temperature and activity levels of pregnant and nonpregnant females during preimplantation, gestation, and lactation. Additionally we tested whether age, litter size, primiparity, environmental conditions, and the start of hibernation influence the timing of parturition. The mean date of implantation was 1 December (SD = 12), the mean date of parturition was 26 January (SD = 12), and the mean duration of the gestation period was 56 days (SD = 2). The body temperature of pregnant females was higher during the gestation and lactation periods than that of nonpregnant bears. The body temperature of pregnant females decreased during the gestation period. Activity recordings were also used to determine the date of parturition. The parturition dates calculated with activity and body temperature data did not differ significantly and were the same in 50% of the females. Older females started hibernation earlier. The start of hibernation was earlier during years with favorable environmental conditions. Dates of parturition were later during years with good environmental conditions which was unexpected. We suggest that free-ranging pregnant brown bears in areas with high levels of human activities at the beginning of the denning period, as in our study area, might prioritize investing energy in early denning than in early parturition during years with favorable environmental conditions, as a strategy to prevent disturbances caused by human.     

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。     

Reproductive seasonality in a free-ranging troop of stumptail macaques (Macaca arctoides): A five-year report

Seasonality in births and fertile matings are reported for a stumptail macaque group living on an island for a period of five years: 1975–1979. During this period 26 births occurred of which 24 represent infants conceived on the island. While births and fertile matings occurred throughout the year 21% of the births were concentrated in March, 34% in June and July and 17% in November. Additionally 63% of the births occurred during the rainy season. Of the 24 infants, 4 died during the first year of life thus yielding a reproductive success of 83%. The sex ratio at birth for the five years was 1:1 corrected to 1:1.2 with the four deaths. The mean interval between fertile matings for females was 19 months and 2 days and the mean age for first conception was 4 years and 5 months. The pattern of birth and breeding seasonality was markedly similar to that of the parent troop while in Puerto Rico.     

四川梅花鹿繁殖行为

2006年4—12月和2007年3—11月在四川省铁布自然保护区观察和统计了野生梅花鹿的繁殖行为,包括发情交配、产仔、发情吼叫、爬跨及其昼夜节律行为等。结果表明,四川梅花鹿为季节性发情动物,发情交配行为发生在9月上旬至12月中旬,集中在10—11月(占(86.99±3.24)%)。四川梅花鹿发情交配日期最早见于9月8日,最晚为12月16日,跨度约90—100 d(±6 d,n=90)。雌鹿交配日期与其繁殖经历具有低度正相关性(Kendall's tau-b和Spearman's rho,0.3r0.5,P0.05),成体雌鹿交配日期稍微早于初次配种雌鹿。雄鹿发情吼叫和爬跨行为具有明显的昼夜节律性,各有2个高峰期(05:00—08:00和18:00—21:00),夜间有小节律的发情吼叫和爬跨时期。U-test检验表明发情吼叫频次和爬跨频率在昼夜间有极显著差异(P0.01)。雄鹿吼叫行为与其交配行为具有高度正相关性(Kendall's tau-b和Spearman's rho,0.8r1.0,P0.05),主雄、次雄和群外单身雄鹿的昼夜吼叫次数有极显著差异(P0.01)。雌鹿产仔期从4月下旬开始到7月下旬结束,集中在5—6月(占(91.51±4.96)%),产仔日期最早见于4月29日,最晚为7月28日,跨度约80—90 d(±5 d,n=130)。梅花鹿产仔日期与其分娩经历具有低度正相关性(Kendall's tau-b和Spearman's rho,0.3r0.5,P0.05),成体雌鹿产仔日期早于初次繁殖雌鹿。雌鹿每胎产1—2个幼仔,单双胎率分别为98.86%(±6.96%,n=129)和1.01%(±0.07%,n=1)。妊娠期和哺乳期梅花鹿采食行为分配占较大比率,其次是卧息和移动,哺乳期采食行为分配低于妊娠期,这与妊娠期正逢冬季,食物资源相对匮乏有关,而哺乳期恰逢夏季,植物生长旺盛,食物资源相对丰富。     

Reproductive behaviour of wild-living wolves in Białowieża Primeval Forest (Poland)

Characteristics of the reproductive behaviour of wolves (Canis lupus) were studied by radio-tracking and snow-tracking of four packs in Białowieża Primeval Forest (BPF), Poland, in 1995–1999. Signs of mating occurred between 12 January and 22 March. Parturition occurred between 19 April and 12 May, and the denning period lasted for 49–64 days. During that time, wolves used 1–3 den sites, spending on average 27 days at each site. The dens were never reused in consecutive years, but year after year the breeding sites were located in the same parts of the pack’s territory. Ten days before parturition pregnant females reduced their normal mobility by half (from 23 to 13.5 km day⁻¹, on average). During the ten days post-partum, they spent 85% of their time with pups and travelled 3.9 km day⁻¹, only. On days 11–30 after parturition, females spent 74% of their time tending pups and increased their daily movement distance to a mean of 13.3 km. The females resumed full mobility 50–70 days after parturition, which coincides with termination of the weaning process. Anecdotal observations indicated that pups were tended by other pack members while the mother was absent. Compared with the years 1947–1950, in 1995–1999 the breeding season of wolves in BPF occurred two weeks earlier. A possible reason was the 1 to 1.5-degree increase in the mean annual temperature during the last 50 years.