Synchrony Of Parturition Research Articles

Impacts of inter-annual climate variability on reproductive phenology and postnatal development of morphological features of three sympatric bat species

Inter-annual variation in weather conditions has been shown to affect the reproductive phenological patterns of many organisms. Because of their relatively small body size and dependence on ectothermic prey, temperate-zone insectivorous bats are particularly sensitive to adverse spring environmental conditions that affect the duration of gestation and timing of parturition in these animals. This study aimed to compare phenological recruitment, birth seasonality and synchrony and morphological changes during postnatal growth in Rhinolophuseuryale, Rhinolophusferrumequinum and Myotisemarginatus in two consecutive years representing a typical dry (2015) and an extremely wet climatic event (2016) in a nursing colony in Kerend cave, western Iran. Females of these three bat species arrived from their wintering cave to the nursing colony in late April to mid-May each year. Synchrony of parturition as defined by amount clustering of births within a year assessed by circular statistics showed that for R. euryale and R. ferrumequinum the angular variance in dry year were significantly (P < 0.05) lower than in wet year, indicating a low level of synchrony in 2016. Similar comparison showed that births from M. emarginatus were highly synchrony, and there were no significant differences in timing of births among years (P > 0.05). Generalized estimating equation (GEE) for R. euryale indicated that for body mass and forearm length tests of parallelism (interaction term or growth rate) and tests for equal intercepts (y-intercepts or group term) were significant (P < 0.001). In R. ferrumequinum, the initial (y-intercepts) forearm length and body mass were not significantly (P > 0.05) different between the 2 years, but the tests for parallelism showed a significant decrease in growth rates of body mass and forearm length in the wet year (P < 0.05). Similar comparison in M. emarginatus indicated that for body mass, tests of parallelism were significantly different (P = 0.004), while tests for equal intercepts were not (P = 0.23). Our results suggest that climate changes may have unequal effects on different bat species due to differences in foraging habitat, niche partitioning, reproductive requirements and foraging strategies.

Birth synchrony and postnatal growth in Rhinolophus ferrumequinum (Chiroptera: Rhinolophidae) in two successive dry (2015) and wet year (2016) in a nursing colony in Kerend cave, western Iran

AbstractSeasonality and synchrony of parturition and postnatal growth in Rhinolophus ferrumequinum have been studied in two consecutive years representing a typical dry (2015) and an extremely wet climatic event (2016) in Kerend cave, western Iran. In 2015, first pup was born on 20 May and by 10 days 85% of neonates were born. In the wet year, first pup was born on 26 May and by 10 days 56% of neonates were born. Synchrony of birth as defined by the clustering of births assessed by circular statistics showed that the angular variance in 2015 (S2 = 0.003) was significantly (p &lt; .05) lower than in 2016 (S2 = 0.006). Multiple regression and generalized estimating equation indicate that the initial (y‐intercepts) forearm length and body mass were not significantly (p &gt; .05) different between the 2 years, but the tests for parallelism shows a significant decrease in growth rates of body mass and forearm length in the wet year (p &lt; .05). In 2016, juvenile bats began their first foraging flights at 24–28 days of age with higher but nonsignificant (p &gt; .05) wing loading (7.71 ± 0.48 N/m2) compared with 2015 (7.65 ± 0.57 N/m2). Similarly, aspect ratio of 1‐day old neonates and juvenile bats in 2015 and 2016 did not show any significant difference (p &gt; .05). Results of the present study suggest that R. ferrumequinum responded to prolonged precipitations and lower temperatures by delaying parturition, reducing birth synchrony and lowering postnatal growths.

Early and late births in high-latitude populations of free-ranging Bison (&lt;i&gt;Bison bison&lt;/i&gt;)

The timing of parturition in high-latitude populations of Bison (Bison bison) is not well documented, but previous observations have indicated that births do not start until mid-May and largely end in late June or early July, similar to those of other northern ungulates. In three high-latitude Bison populations in northwestern Canada, the onset of parturition occurred as early as late March and early April—5–6 weeks earlier than previously observed—and two isolated cases of late births occurred in mid-November and mid-December. Our observations suggest that the onset of parturition in high-latitude Bison can be earlier than previously known, and late births, while apparently rare, may occur. Determining whether our observations signal a substantial, lasting shift in the timing and, possibly, synchrony of parturition in high-latitude populations of Bison will require further monitoring for early-born calves.

Effects of male-biased harvest on mule deer: Implications for rates of pregnancy, synchrony, and timing of parturition

Evaluating how management practices influence the population dynamics of ungulates may enhance future management of these species. For example, in mule deer (Odocoileus hemionus), changes in male/female ratio due to male-biased harvest may alter rates of pregnancy, timing of parturition, and synchrony of parturition if inadequate numbers of males are present to fertilize females during their first estrous cycle. If rates of pregnancy or parturition are influenced by decreased male/female ratios, recruitment maybereduced (e.g., fewerbirths,laterparturition resultinginlower survivaloffawns, andalesssynchronous parturition that potentially increases susceptibility of neonates to predation). Our objectives were to compare rates of pregnancy, synchrony of parturition, and timing of parturition between exploited mule deer populations with a relatively high (Piceance, CO, USA; 26 males/100 females) and a relatively low (Monroe, UT, USA; 14 males/100 females) male/female ratio. We determined rates of pregnancy via ultrasonography and timing of parturition via vaginal implant transmitters. We found no differences in rates of pregnancy (98.6% and 96.6%; z ¼� 0.821; P ¼0.794), timing of parturition (estimate ¼1.258; SE ¼1.672; t ¼0.752; P ¼0.454), or synchrony of parturition (F ¼1.073 P ¼0.859) between Monroe Mountain and Piceance Basin, respectively. The relatively low male/female ratio on Monroe Mountain was not associated with a protracted period of parturition. This finding suggests that relatively low male/female ratios typical of heavily harvested populations do not influence population dynamics because recruitment remains unaffected. 2014 The Wildlife Society.

YELLOWSTONE BISON FETAL DEVELOPMENT AND PHENOLOGY OF PARTURITION

Abstract Knowledge of Yellowstone bison (Bison bison) parturition patterns allows managers to refine risk assessments and manage to reduce the potential for transmission of brucellosis between bison and cattle. We used historical (1941) and contemporary (1989–2002) weights and morphometric measurements of Yellowstone bison fetuses to describe fetal growth and to predict timing and synchrony of parturition. Our method was supported by agreement between our predicted parturition pattern and observed birth dates for bison that were taken in to captivity while pregnant. The distribution of parturition dates in Yellowstone bison is generally right-skewed with a majority of births in April and May and few births in the following months. Predicted timing of parturition was consistently earlier for bison of Yellowstone's northern herd than central herd. The predicted median parturition date for northern herd bison in the historical period was 3 to 12 days earlier than for 2 years in the contemporary period, respe...

Life-History Consequences of Maternal Condition in Alaskan Moose

We studied life-history characteristics of Alaskan moose (Alces alces gigas) including the effects of maternal condition of adult females (>33 months old) on sunival and physical condition of young during their first year-of-life. We also examined the relation behveen maternal condition and reproductive parameters of individual adult moose, and tested for effects of those parameters on timing and synchrony of parturition. \t7e radiotracked adult fernales captured in both March 1996 and 1997 throughout the year with intensive monitoring occurring during spring and early summner. That procedure enabled us to capture the offspring of females xire monitored and record other variables related to reproductive success. Females with greater nlmp fat thickness had higher rates of pregnancy, gave birth to more hvins. and produced young with higher birth masses than did females with less rump fat. Time-to-death for indi~idual young increased as birth rnass increased and decreased as birth date and litter size increased; those birth variables, lio\ve\~er. did not act upon time-to-death independently. Our results indicated maternal condition influenced subsequent variables associated wit11 birth, which ultimately affected f i~ t~ t r e sunival of offspring. Further, timing of reproduction varied behveen the 2 years, with births occurring earlier but not more synchronously i11 1996 than in 1997. Time of parturition occurred earlier for individual ferr~ales with the thickest rump fat. That outcolne indicated that timing of parturition was the result of e~nironmental factors acting on fe~nales prior to giving birth rather than effects of attempting to avoici predation. JOURNAL OF WILDLIFE MANAGEMENT 64(2):450-462

Timing and Synchrony of Parturition in Alaskan Moose: Long-Term Versus Proximal Effects of Climate

We studied timing and synchrony of parturition in Alaskan moose ( Alces alces ) in Denali National Park and Preserve, Alaska, from 1990 to 1994. Mean date of birth was 25 May ( SD = 5.7 days) and did not differ significantly among years. Although moose did not congregate to give birth, parturition was highly synchronized (95% of births occurred in 16 days) with no significant differences among years. Most young moose were killed by predators, especially grizzly bears ( Ursus arctos ), but timing of reproduction had no effect on survivorship of young, which was low (ca. 0.2 by 16 June). We reject the hypothesis that moose timed births to avoid predation. We also measured depth of snow in winter, and precipitation, cloud cover, and temperature in spring; none of these variables was related to timing or synchrony of births. Likewise, quality of willow ( Salix pulchra ) in 3 springs in which percent nitrogen and in vitro dry-matter digestibility of this important forage varied markedly was unrelated to timing of births. We reject the hypothesis that moose timed parturition in response to proximal changes in their environment. We hypothesize that both timing and synchrony of parturition in moose are adaptations to long-term patterns of climate that provide the most hospitable conditions to bear and rear young. Consequently, moose may be more susceptible to climatic change than other ungulates that are more adapted to climatic variability.

Timing and Synchrony of Parturition in Alaskan Caribou

Timing of parturition of caribou ( Rangifer tarandus ) varies within populations, but the relative influences of nutritional condition of females during the autumn breeding season and during gestation on that variation is not known. We determined timing of parturition of caribou in Denali National Park, Alaska, during 1984–1995, which had wide variation in snowfall that influenced nutritional condition and productivity of females. The first young were observed each year between 4 and 15 May. Annual median dates of parturition for radiocollared females during 1987–1995 varied from 13 to 21 May. Synchrony of births (i.e., proportion of births during 7 days centered on the median date) did not vary significantly among years ( P > 0.05). Females ≤4 years old were more likely to give birth after the annual median date than older females ( P = 0.005). Dates of parturition were significantly correlated with masses of females in the previous autumn ( P = 0.034) but not in late winter ( P = 0.155). Births tended to be earlier for parous females that were not lactating during the previous breeding season compared to those that were lactating ( P = 0.030). Annual onsets of parturition varied significantly with snowfall in late winter prior to conception ( P = 0.012) but not with snowfall during gestation. Timing of parturition in our study appeared to be a function of physical condition of breeding females in autumn.

Interannual Variation in Timing and Synchrony of Parturition in Dall's Sheep

Timing and synchrony of parturition in Dall's sheep ( Ovis dalli ) were studied in Igloo Mountain, Denali National Park and Preserve, Alaska, from April through July 1988 and 1989. Median ± SD dates of birth were 18 May (±5.1 days) in 1988 and 27 May (±8.8 days) in 1989. Ninety percent of births occurred in a 27-day period in 1988 and in a 36-day period in 1989; interannual variation in timing and synchrony of parturition was pronounced. Mortality of young in this predator-rich environment, however, did not differ between years, suggesting climatic variability may contribute more than predation in constraining timing and synchrony of parturition in Dall's sheep.

Induction of parturition in sheep using oestradiol benzoate

The efficacy of oestradiol benzoate (ODB) in inducing parturition in Dorset Horn x Merino ewes was examined in two trials conducted at the Agricultural Research Station, Condobolin during the autumn and spring of 1974. In the first trial ewes were given either 10, 20 or 40 mg of ODB i.m. as a single dose between days 140 and 144 of gestation. In the three days following treatment 50 per cent of untreated ewes lambed. Of the treated ewes, 14.7 per cent lambed on the first day after treatment, 79.4 per cent lambed on the second day after treatment and 5.9 per cent lambed on the third day after treatment. Abortion was induced in 40 to 70 per cent of ewes inadvertently treated on days 126 to 130 of gestation, with all lambs born dead or dying. In a second trial ODB was effective in inducing parturition at doses as low as 7.5 mg. For ewes treated at 141 days of gestation optimal synchrony of parturition, between 35 and 50 hours after treatment, was obtained with doses of 20 and 30 mg ODB. Lamb losses (19 to 23 per cent) in treated ewes were similar to those for untreated ewes. ODB was superior to either a short or long acting corticoid (Dexamethasone) in synchronizing and inducing parturition in ewes treated at 141 days of gestation. Lambs born prematurely grew at least as well as lambs born at the normal time.