Placental Scars Research Articles

Assessment of reproduction of brown bears in Sweden using stained placental scars

The Swedish brown bear Ursus arctos population is protected, but managed with legally defined hunting seasons. Management decisions (e.g., hunting quotas) are frequently changed and should be based on knowledge about demographic parameters, but collecting sufficient data in the field is time consuming and expensive. An efficient method to collect data on reproductive output could be counting placental scars in the uteri of female brown bears, because hunters in Sweden are required to collect samples (including reproductive organs) of harvested bears and submit them to the authorities. We assessed the reliability of placental scar counts to determine reproductive performance by counting the number of young with female radio-collared brown bears and comparing that with placental scar counts after those females had been harvested. We found that staining uteri improved the detection of placental scars. The differences between number of scars detected before and after staining the uteri, increased significantly with female age. The number of placental scars and number of observed cubs-of-the-year accompanying females corresponded well 2 and 3 years after birth; relatively small deviations between them might have occurred because of early cub mortality prior to the observations after leaving the den. Placental scar counts can provide accurate information on age of primiparity, evidence for reproductive aging (senescence), and reproductive productivity, and therefore inform decisions regarding adaptive management, sustainable hunting, and conservation.

Application of bivariate regression method for estimating the secondary natality in brown hare

Knowledge of reproductive performance of the European brown hare (Lepus europaeus, Pallas, 1778) is an essential condition for planning rational utilization. The direct possibility of estimating the number of leverets is the placental scar counting of the eviscerated females in the hunting bag. A condition for a reliable estimate is a sufficient sample quantity and the timing of sampling. Late sampling leads to a risky and unreliable estimate due to the disappearance of placental scars (amount of reproduction), which will result in under- or over-utilization. The goal of study is to test a method that enables reliable estimation for the amount of reproduction by using individual biological parameters and eliminates the risk resulting from timing. This case report is an attempt to estimate the number of placental scars (born leverets) by using the dried eye lens weight and body weight of fertile females by bivariate linear regression method. Based on the real placental scar number (y), three classes were created: class I: y=1-4; class II: y=5-9; class III: y=9-13 placental scares. The estimated values of the placental scar numbers (y’) using the regression model was only accurate for values belonging to class II. For those belonging to class I the model resulted over-, and to class III an underestimation. The linear regression model using eye lens weight and body weight as independent variables did not result in a reliable estimate of secondary natality for the entire stock in the given situation.

Characteristics of reproductive organs and reproductive potential in Scandinavian female grey wolves (Canis lupus).

The Swedish wolf population is closely monitored and managed to keep the population at a sustainable level while avoiding conflicts. Detailed knowledge about reproduction is crucial for estimates of population size and the reproductive potential of a population. Post-mortem evaluation of reproductive organs can be used as a complementary tool to field monitoring for evaluation of cyclicity and previous pregnancy, including litter size. Therefore, we evaluated reproductive organs from 154 female wolves that were necropsied during the period 2007–2018. The reproductive organs were weighed, measured, and inspected according to a standardised protocol. Presence of placental scars was evaluated for estimates of previous pregnancy and litter size. Data about individual wolves were also obtained from national carnivore databases. Body weight increased during the first year of life before levelling out. There was evidence of cyclicity the first season after birth in 16.3 % of the 1-year-old females. No females < 2 years had evidence of a previous pregnancy. Pregnancy rates were significantly lower in 2- and 3-year old females than in older females. Mean uterine litter size was 4.9 ± 2.3, and did not differ significantly between age groups. Our data supports earlier field data that female wolves usually start to reproduce at the earliest at 2-years of age but that they occasionally start to cycle one season earlier. All females ≥ 4 years of age had reproduced. Pathological findings of the reproductive organs were rare, indicating that reproductive health of female wolves is not a limiting factor for population growth.

Maize monoculture causes niacin deficiency in free-living European brown hares and impairs local population development

Maize (Zea mays) is the most produced crop worldwide and the second most important bio-energy plant. Huge maize monoculture is considered a threat to biodiversity in agricultural landscapes and may also contribute to the decline of European brown hares (Lepus europaeus, Pallas 1778). Indeed, the intensification of agriculture has been identified as one of the main factors responsible for the decline of brown hare populations. A reason why large maize cultures can be particularly detrimental to animals consuming this plant is its poor nutritional value with respect to niacin. In this study, we investigated the effects of the proportion of area under maize crops on liver concentrations of niacin in free-living hares, on the reproductive output of does (females), and on the development of local populations, at nine study sites in Lower Austria. Hare numbers were estimated from spotlight counts in spring and autumn. Liver samples and uteri were obtained from hares shot in the same areas during regular autumn hunts. Number of offspring born to an individual female during the preceding reproductive period was determined by counting placental scars. Our results show a significant negative effect of the area under maize crops on liver concentrations of niacin of does and on their reproductive output. Further, we found a significant negative effect of the area under maize on the development of a population. Altogether, our findings indicate that high proportions of the area under maize crops contribute to the decline of brown hares by reduced fecundity of does and impaired development of local populations.

Influence of multiple predators decreases body condition and fecundity of European hares.

We assessed the hypothesized negative correlation between the influence of multiple predators and body condition and fecundity of the European hare, from 13 areas in the Netherlands.Year‐round abundance of predators was estimated by hunters. We quantified predator influence as the sum of their field metabolic rates, as this sum reflects the daily food requirements of multiple individuals. We determined the ratio between body mass and hindfoot length of hares as an index of body condition and the weight of their adrenal gland as a measure of chronic exposure to stress, and we counted the number of placental scars to estimate fecundity of hares.As hypothesized, we found that the sum of field metabolic rate of predators was negatively correlated with body condition and the number of placental scars, whereas it was positively related to the weight of the adrenal glands. In contrast to the sum of the field metabolic rate, the total number of predators did not or weakly affect the investigated risk responses.The sum of the field metabolic rate can be a useful proxy for the influence of multiple predators and takes into account predator abundance, type, body weight, and food requirements of multiple predators.With our findings, our paper contributes to a better understanding of the risk effects of multiple predators on prey fitness. Additionally, we identify a potential contributor to the decline of European hare populations.

Pathological Findings in Eurasian Otters (Lutra lutra) Found Dead between 2015-2020 in Schleswig-Holstein, Germany.

Simple SummaryWorking with protected and elusive wildlife species remains a challenge when it comes to population health investigations. Specimens found dead, such as road-killed animals, can therefore serve as a valuable source to address various questions concerning the population level. We herein describe pathological findings in Eurasian otters found dead in Schleswig-Holstein, Germany, which were obtained using a special otter dissection protocol. To actually monitor population trends and the health of otters, the continuation of post-mortem investigations is essential.In times of massive biodiversity loss and ongoing environmental crises, it is extremely important to ensure long-term conservation efforts of threatened species like Eurasian otters (Lutra lutra). To gain insights into the status of Northern Germany’s otter population, 92 otters found dead in Schleswig-Holstein between 2015−2020 were collected and underwent detailed dissection with the aim to establish a monitoring program for this population. Examinations followed a protocol especially designed for otters, including various biological data assessments and extended sampling. The finding sites showed a clear concentration in the Continental region. Seasonal concentration differed among the years, yet peaks were seen from fall to winter. Overall, more males than females were found, although this differed among the years. The majority of otters that could be aged were between 1–3 years. Placental scars and pregnancy were recorded in only few females. Nutritional status was good in most cases. Infectious diseases found included Vagococcus lutrae, Toxoplasma gondii, and Emmonsia spp. A major cause of death was roadkill. Known sample bias in studies focusing on roadkill was considered in the finding interpretation. Continuation of the population health investigations is mandatory to analyze potential trends and to establish an actual monitoring program for Eurasian otters in Schleswig-Holstein.

Contributions from terrestrial and marine resources stabilize predator populations in a rapidly changing climate

AbstractClimate change has different and sometimes divergent effects on terrestrial and marine food webs, and in coastal ecosystems, these effects are tightly interlinked. Responses of opportunistic coastal predators and scavengers to climate change may thus be complex and potentially highly flexible, and can simultaneously serve as indicators of, and have profound impacts on, lower trophic levels. Gaining mechanistic understanding of these responses is therefore important, but often not feasible due to lack of long‐term data from marked individuals. Here, we used a Bayesian integrated population model (IPM) to elucidate the effects of arctic warming and concurrent changes in terrestrial and marine resource availability on population dynamics of the opportunistic arctic fox (Vulpes lagopus) in Svalbard. Joint analysis of four types of data (den survey, age‐at‐harvest, placental scars, mark‐recovery) revealed relatively stable population size and age structure over the last 22 yr (1997–2019) despite rapid environmental change linked to climate warming. This was related to the fact that terrestrial resources (reindeer carcasses, geese) became more abundant while the availability of marine resources (seal pups/carrion) decreased, and was driven by divergent trends in different vital rates (e.g., increased pregnancy rate but decreased pup survival). Balanced contributions of survival vs. reproduction and of immigration vs. local demography further stabilized population size. Our study thus sheds light on the mechanisms underlying population dynamics of opportunistic carnivores exploiting terrestrial and marine resources and suggests that exploitation of resources across different ecosystems can buffer predators against climate change. Additionally, it highlights the large potential of IPMs as tools to understand and predict the effects of environmental change on wildlife populations, even when data on marked individuals are sparse.

THE INFLUENCE OF DIFFERENT TYPES OF CHRONOTYPE ON SCAR FORMATION DURING THE USE OF PLACENTAL CRYOEXTRACT AT THE INTRAOPERATIVE STAGE

To define the individual features of the organization of circadian rhythms, the term "chronotype" was proposed, which is becoming increasingly popular in research in the field of medicine. According to the analysis of literature data, biological rhythm affects not only the mental state, obesity but the human condition as a whole. Biological rhythms are a manifestation of the fundamental properties of the organic world, provide the ability of man to adapt and survive in the environment. In this aspect, of particular interest is the functioning of the organism, taking into account its individual characteristics in terms of the organization of biorhythmic processes. The research was conducted on the basis of the Department of Maxillofacial Surgery on the basis of CE «Poltava M. V. Sklifosovskyi Regional Clinical Hospital of the Poltava regional council». A total of 24 patients participated in the study. To study the materials, we analyzed patients who were hospitalized for routine surgery for congenital neck cysts and tumors of the head and neck. Patients were interviewed during hospitalization, as well as a questionnaire to determine the chronotype. Patients were divided into the following 2 groups, namely: group 1, which in turn comprised 2 subgroups: 1.1 - Patients with morning chronotype; 1.2 - Patients with evening chronotype. The first subgroup (1.1 - with the morning chronotype) consisted of 7 subjects who underwent surgery in the morning. The second subgroup (1.2 - with evening chronotype) consisted of 9 patients who underwent surgery at about 15:00. In each of these subgroups during surgery, intradermal administration of the drug "Cryocel" was performed. - group 2 (control). The second control group consisted of 8 patients, all patients in this group were operated on according to the classical method without the use of additional preventive measures. On the 90th day of the clinical study, we could observe a significant difference in the comparison of postoperative scars, namely in patients with morning chronotype and in patients with evening chronotype it was 42%, the difference with control was 71% and the difference between the subgroup 2 and the control group was 50%. On the 180th day of the study, we observed a significant difference between the groups, in patients of subgroups 1 and 2, as compared to the control group, clinical data in the description of postoperative scars were better by 25%. When comparing subgroups 1 and 2, no difference was observed. Thus, on the 180th day when examining patients, the clinical picture was more favorable in subgroups 1 and 2. According to the data obtained, we can say that in patients who underwent surgery in the morning and injected with placental cryoextract, wound healing and scar formation on the 90th day was faster and better than in patients who underwent surgery at lunchtime, and patients who underwent surgery according to the classical method without the use of additional preventive measures.

Demographical and morphological differences among coyotes (Canis latrans) relative to sampling method

Collection methods can be biased, leading to misperceptions of population composition. We tested if collection method (footholds, snares, and shooting) gave different perceptions of demography or morphology of 3539 eastern coyotes (Canis latrans Say, 1823). We found no differences in sex ratios of animals among methods, but did find some evidence that younger, lighter, and smaller animals were more likely to be collected by footholds than with snares. Female reproductive histories (placental scars) did not differ among methods. In a subsample of 232 animals, we found no evidence of differences in helminth parasitism relative to collection method. Overall, our large sample for the non-parasite analyses facilitated finding statistical significance; the biological implications hinge on the precision required in estimating population composition and the focal characteristics being compared. For example, mass was 5.3% lower for coyotes caught with footholds versus snares and 10.4% lower for coyotes caught with footholds versus being shot, whereas linear trait measurements of coyotes caught with footholds were generally smaller by at most 4.5% compared with other methods (broadly consistent with linear versus volumetric measurements). Our study provides important baseline information for making inferences about populations of coyotes (and other species) sampled using only a single collection method.

Pregnancy-induced long-term uterine vascular remodeling in the rat

Despite the available research investigating uterine physiology during and immediately following pregnancy, including at the vascular and muscular levels, knowledge of the potential long-term timeline of such changes is limited. Thus, our study sought to investigate the potential long-term changes in uterine vasculature and horn length in the postpartum rat, following delivery and weaning. Female Long-Evans rats (n = 9–11 rats/group/timepoint) were divided into two groups: a pregnant group and an age-matched virgin control group. Rat weight, food consumption and vaginal impedance measurements were recorded throughout the experiment. Rats in the pregnant group were bred and pregnancy was confirmed using ultrasound imaging. The uterus and its vasculature were collected at various timepoints following weaning: 3 (week of weaning), 8–9 and 13 weeks postpartum, and at age-equivalent timepoints in the virgin group, and the diameters of the main uterine artery and vein, and lengths of the mesometrial segmental vessels (MSV) and uterine horns were recorded. The results indicated a significant difference between the previously-pregnant and virgin rats in both internal and external arterial diameters (but not arterial wall thickness), as well as the uterine horn length, 3 weeks postpartum, but not 8–9 and 13 weeks postpartum. Significant differences were observed in both venous diameter and MSV length at all timepoints measured. Placental scars were also observed in previously-pregnant rats at all timepoints measured. Our study highlights the long-term impact of pregnancy on the uterine vasculature and the necessity for consideration of such changes on subsequent pregnancies, as well as pregnancy-related vascular pathologies.

Modelled population growth based on reproduction differs from life tables based on age determination in Danish raccoon dogs (Nyctereutes procyonoides)

The population of raccoon dogs (Nyctereutes procyonoides) in Denmark has increased rapidly from 1995 when the first was recorded until today where 3291 raccoon dogs are trapped, shot by hunters or road killed. The aims of this study are to present the first data on reproduction and life tables of raccoon dogs in Denmark and to compare mortality from modelled life tables with game bag records and sampled raccoon dogs in different age groups. In this study, the uteri of 89 adult females (> 10 months) were examined for placental scars (PSC), and 561 individuals (289 males, 272 females) were aged using pulp cavity width and dental lines in canine teeth. The litter size of raccoon dogs in Denmark is to date the largest litter size recorded in the wild (mean ± SE) 10.8 ± 0.4, range 1–16 pubs and fecundity 8.4 ± 0.6 pubs. The percent-reproducing females are 78–83%, based on dark and all PSC, respectively. A significant difference was found between the proportion of individuals composing the different age groups based on age determination of individuals collected (Ntage) and the modelled number of individuals in age groups based on fecundity and different mortality rate (Ntmodel), X2 = 8, p < 0.05. The discrepancy between the relatively high reproduction and lifetables may be due to older and more experienced animals that avoid culling. A low population density in a newly founded Danish population of raccoon dogs, together with a milder climate where raccoon dogs can forage during the winter, may cause an exceptionally high reproduction in Danish raccoon dogs.

Difference in the factors of effect on reproductive rate of feral raccoon (Procyon lotor) between high- (2008-2010) and low- (2015-2017) density terms in Kanagawa Prefecture, Japan

Difference in the factors of effect on reproductive rate of feral raccoon (Procyon lotor) between high- (2008-2010) and low- (2015-2017) density terms in Kanagawa Prefecture, Japan

Formation and Diachronic Changes of Placental Scars in the House Shrew (Suncus murinus)

In the present study, diachronic changes in fresh and stained placental scars of postpartum house shrews (Suncus murinus) were studied and compared with the actual number of offspring. In non- stained fresh uteri, the placental scars were barely visible externally, except in some exceptional cases. In stained uteri, placental scars were observed in all specimens, even in the oldest animals evaluated (12 months postpartum). The study estimated the number of offspring and time of parturition using the degree of staining in the scars and the change in their forms. As the time postpartum increased, the stained placental scars became discoloured and shrank, making it difficult to distinguish between the scars from normal parturition and those that formed following halted development after implantation. Placental scars provided an invaluable method for estimating the female reproductive state in wild mammals. In captive house shrews, however, placental scars were barely detected in non- stained fresh uteri. Moreover, placental scars were observed in older animals at 12 months postpartum. It can be concluded that, it is not feasible to estimate the number of offspring or time of parturition based on placental scars in wild shrews, which are believed to undergo multiple parturitions a year.

鄱阳湖区黄毛鼠(Rattus losea)繁殖生态

PDF HTML阅读 XML下载 导出引用 引用提醒 鄱阳湖区黄毛鼠(Rattus losea)繁殖生态 DOI: 10.5846/stxb201708021384 作者: 作者单位: 江西省科学院生物资源研究所,江西省科学院生物资源研究所,中国科学院亚热带农业生态研究所,江西省科学院生物资源研究所,中国科学院亚热带农业生态研究所,江西省科学院生物资源研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 江西省自然科学基金项目（20151BAB204010）；江西省科技计划项目（20151BBG70065）；国家自然科学基金项目（41561056）；江西省科学院项目（2014-YYB-05，2014-XTPH1-05） Reproductive ecology of Rattus losea populations in the Poyang Lake region Author: Affiliation: Institute of Biological Resources,Jiangxi Academy of Sciences,Institute of Biological Resources,Jiangxi Academy of Sciences,Institute of Subtropical Agriculture,Chinese Academy of Sciences,Institute of Biological Resources,Jiangxi Academy of Sciences,Institute of Subtropical Agriculture,Chinese Academy of Sciences,Institute of Biological Resources,Jiangxi Academy of Sciences Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:2015-2016年对鄱阳湖区的滨湖农田和湖滩草洲的黄毛鼠种群繁殖进行了研究。研究结果表明，其种群雌雄比为81.36%，在不同的季节、生境和年龄组之间都有一定的差别，雌雄比在夏季较低，春、秋、冬季的雌雄比都超过了50.00%，其中冬季的达到了133.33%。农田和湖滩草洲上的雌雄比也都超过了50.00%，且农田的高于湖滩草洲的。在不同的年龄组之间，雌雄比最高的为幼体组140.00%，其次为成体90.20%。所有雌鼠全年的怀孕率为45.26%，平均胎仔数为6.74只，繁殖指数为1.36。夏和秋季的怀孕率都较高，冬季未捕获到怀孕鼠，仅捕获到有怀孕经历（有宫斑）的雌鼠。从繁殖指数看，春、秋季维持高峰水平，且秋峰高于春峰。雌性黄毛鼠总的参产率为71.58%，各季节间变化呈现单峰曲线，夏季最高，其次是秋季和春季，冬季停止怀孕。随着年龄的增长，平均胎仔数有明显增加的趋势，成体组胎仔数最高，而繁殖指数也是以成体组最高，说明成体组是种群中繁殖的主体。雄性黄毛鼠的睾丸下降率全年总计为81.36%，分四季平均为79.64%，春、夏、秋季都维持在较高水平，冬季最低。下位睾丸的大小季节性差异极显著（P < 0.01），春季与冬季相比，有显著性差异，说明开春后，雄性黄毛鼠在生殖潜能上已有明显变化。这些特征与雌鼠的繁殖高峰基本吻合。说明黄毛鼠主要在春、夏、秋季繁殖，繁殖盛期在春、秋季。从不同的年龄组看，幼体组个体不参与繁殖，亚成体组个体开始参与繁殖，繁殖主体是成体组个体。 Abstract:Rattus losea individuals were collected from beaches and farmland of the Poyang Lake region in 2015 to 2016. A total of 175 specimens were captured, and 171 animals were autopsied to determine their reproductive condition. Position and size of testes were noted in males. For females, the reproductive tract was examined for the tubal condition of the uterus, number and size of embryos, and placental scars. Specimens were assigned to three age classes based on carcass weight:juvenile (carcass weight ≤ 36 g), sub-adult (carcass weight from 36 to 55 g), and adult (carcass weight > 55 g). Males with testes that had dropped into the scrota and females for which the uterus was tubal were considered sexually mature. Females with embryos or visible uterine scars were considered reproductive animals. The total sex ratio (F/M) was 81.36%, but it varied in different seasons and among different age classes. The proportion of males was higher than that of females, except during summer, and the female-male ratio in spring, autumn, and winter was greater than 50.00%, reaching 133.33% in winter. The female-male ratio was also more than 50% in farmland and beaches, although it was higher in farmland. Among the different age groups, the ratio was the highest in juveniles (140.00%), followed by that of adults (90.20%). The total percentage of pregnancy in captured females was 45.26%. The average number of embryos in a litter was 6.74, and the index of reproduction for all females was 1.36. Rates of pregnancy were higher in summer and autumn, with no breeding in winter. The index of reproduction was higher in spring and autumn, and exhibited an obvious bimodal characteristic, of which the major peak was in autumn. It was shown that spring and autumn were the peak breeding periods for females. The total rate of reproductive in females was 71.58%. Seasonal variation showed a single peak curve, which was the highest in summer, followed by autumn and spring, with no pregnant females in winter. With increasing age, the average number of embryos in a litter increased significantly. Litter size and the reproductive index were highest in the adult group. The main group to reproduce was the adult class. For males, the rate of testes in scrota for all males was 81.36%, and the four seasons averaged 79.64%. Almost all captured males had scrotal testes in spring, summer, and autumn, whereas the rate of scrotal testes in winter (25.93%) was lower. The size of testes in scrota of mature males changed significantly among seasons (P < 0.01), and there was a significant difference between spring and winter. These data showed that the reproductive potential of males exhibited obvious changes after spring. Reproductive traits of males were similar to those of females by season and age class. As such, it could be concluded that the rat breeds during the spring to autumn, and stops breeding in winter. The most favorable breeding seasons of this species are spring and autumn, and the adult group is the main reproductive class. 参考文献 相似文献 引证文献

Does prey density predict characteristics of primiparity in a solitary and specialized predator, the Canada lynx (Lynx canadensis)?

Age at primiparity is a flexible life-history trait that purportedly responds to changing population dynamics and variable resource abundance. We examined placental scars in yearling Canada lynx (Lynx canadensis (Kerr, 1792)) from the island of Newfoundland and used pregnancy rates and litter sizes to indicate primiparity. We modelled these lynx productivity data with snowshoe hare (Lepus americanus Erxleben, 1777) population attributes using seven multiple a priori competing hypotheses. Hare abundance showed peak, decline, and increase phases, and densities based on capture–mark–recapture estimates ranged from 0.11 to 1.19 hares·ha−1. Overall, yearling pregnancy rate was 23.5% and the model with hare abundance fitted alone had the most support. However, surprisingly hare abundance explained little (6%) variation in yearling pregnancy rate. Mean (±SE) litter size was 3.51 ± 0.27. None of our covariate models provided unequivocal support for predicting yearling litter size. We speculate that individuals may exhibit behavioural plasticity such that they can dampen the impact of primary prey abundance on yearling pregnancy rate by exploiting alternate prey. Furthermore, intraspecific social interactions may provide additional insight into the determinants of pregnancy rate in yearling lynx.

Rural populations of the red fox Vulpes vulpes show little evidence of reproductive senescence

The ageing theory predicts fast and early senescence for fast-living species. We investigated whether the pattern of senescence of a medium-sized, fast-living and heavily-culled mammal, the red fox (Vulpes vulpes), fits this theoretical prediction. We used cross-sectional data from a large-scale culling experiment of red fox conducted over six years in five study sites located in two regions of France to explore the age-related variation in reproductive output. We used both placental scars and embryos counts from 755 vixens’ carcasses aged by the tooth cementum method (age range: 1–10), as proxies for litter size. Mean litter size per vixen was 4.7±1.4. Results from Generalized Additive Mixed Models revealed a significant variation of litter size with age. Litter size peaked at age 4 with 5.0±0.2 placental scars and decreased thereafter by 0.5 cubs per year. Interestingly, we found a different age-specific variation when counting embryos which reached a plateau at age 5–6 (5.5±0.2) and decreased slower than placental scars across older ages, pointing out embryo resorption as a potential physiological mechanism of reproductive senescence in the red fox. Contrary to our expectation, reproductive senescence is weak, occurs late in life and takes place at an age reached by less than 11.7% of the population such that very few females exhibit senescence in these heavily culled populations.

Reproductive characteristics of a coyote population before and during exploitation

ABSTRACTThe eastward expansion of coyotes (Canis latrans) has brought the species into ecosystems and landscapes different from those it historically occupied, yet little is known about the reproductive biology of coyotes in the southeastern United States or the effects of exploitation on reproduction in coyotes. Our objective was to quantify litter size, pregnancy rate, and fecundity in an essentially unexploited coyote population in South Carolina, USA and to evaluate the effect of exploitation on these parameters. We examined reproductive tracts from 235 female coyotes trapped during 2010–2012. Placental scars from coyotes trapped during 2010 indicated that prior to trapping (2009), pregnancy rates were zero for juveniles, 0.25 for yearlings, and 0.389 for adults. Litter size for adults during 2009 averaged 5.4 pups/female, resulting in fecundity of 2.1 pups/female. The number of coyotes trapped was similar among years, indicating that the population recovered following trapping each year, but it shifted toward a younger age structure during trapping. However, although pregnancy rate, litter size, and fecundity of adults all tended to increase from pre‐trapping (2009) through the last trapping period (2011–2012), differences were not significant for this or any other age class. Fecundity of the population did not significantly increase during the first year of trapping (2010) but was lower during the last trapping period (2011–2012; 0.56 ± 0.15 [95% CL]) than prior to trapping (0.90 ± 0.15 [95% CL]). Thus, we observed only weak evidence for compensatory reproduction in response to trapping pressure and conclude that the increase in the juvenile component of the population was attributable primarily to immigration from neighboring areas rather thanin situreproduction. This increased representation of juveniles in the population, which rarely bred, coupled with a concurrent decrease in adults, which accounted for 59.2% of breeding, explains the reduction in population fecundity. High immigration rates as indicated herein render coyote populations extremely difficult to control. © 2017 The Wildlife Society.

Is reproductive strategy of Alpine mountain hares adapted to different elevations?

In Lepus, litter size is inversely related to the duration of the reproductive season resulting in a consistent yearly production of around ten leverets per female. In high latitudes, animals have few litters with large litter sizes, whereas in low latitudes, several litters with small litter sizes are common per year. Knowledge on reproductive performance of Alpine mountain hares (Lepus timidus varronis) is scarce. In this study, we analysed 89 hares from Grisons, Switzerland, by examining placental scars and eye lens weight. The general aim of the survey was to examine the reproductive performance of female Alpine mountain hares. In particular, we focused on the question whether this subspecies adjusts the reproductive strategy in relation to elevation such as other Lepus species do in relation to latitude. All adults of our sample reproduced. 39% of the females littered twice and 61% three times a year with a median litter size of 3.00. We identified a significant effect of elevation on litter size, whereas the elevation did not influence the number of litters. We found no significant difference of yearly reproductive output across elevation range. Hence, some reproductive parameters seem to indicate that the Alpine mountain hare changes the reproductive strategy in relation to elevation similar to the mountain hares living further north do in relation to latitude.

Estimation of reproductive parameters and their annual variation in brown bears of Hokkaido, Japan

Abstract The reproductive tracts of 130 adult female brown bears (Ursus arctos) in Hokkaido, Japan, euthanized during 2010–2013 for conflict management, were examined for the presence and number of corpora lutea (CL) in the ovary and placental scars (PS) in the uterine horns. We scored PS on a 0–5 scale based on morphological features including their rim and color. They were characterized as representing either current-year parturition, as determined by accompanying cubs, or previous-year parturition, as determined by accompanying yearlings. In total, 128 females were divided into 3 reproductive categories: 44 females with current-year parturition, 39 with previous-year parturition, and 45 solitary females that had not given birth for >2 years. The estimated ovulation rate was 2.21 ± 0.55 (mean ± SD), the implantation rate was 1.91 ± 0.74, and the litter size was 1.54 ± 0.51. Implantation rates were lower than ovulation rates and changed annually during 2010–2013. Systematic observation of PS and CL allow...

The short-term impact of abundant fruit upon deer mouse (Peromyscus maniculatus), southern red-backed vole (Myodes gapperi), and woodland jumping mouse (Napaeozapus insignis) populations

Fruit has been identified as an important and potentially population-restricting food for southern red-backed voles (Myodes gapperi (Vigors, 1830)), deer mice (Peromyscus maniculatus (Wagner, 1845)), and woodland jumping mice (Napaeozapus insignis (Miller, 1891)). We added domestic dried strawberries (Fragaria × ananassa (Weston) Duchesne ex Rozier (pro sp.)) and European black currants (Ribes nigrum L.), which have native analogues and are preferred foods of these rodents, to white spruce (Picea glauca (Moench) Voss) plantations from May through August 2011 and 2012 to test fruit and fruit-based carbohydrate’s short-term (1–2 years) impact on these rodent populations. We used mark–recapture to estimate density, percentages of population that were juvenile and breeding female, mean home-range size, and body mass during spring and summer of both years, and fecundity via placental scars from euthanized females in summer 2012. Fruit enhancement had no apparent effect on our species’ fecundity, proportion of breeding females or juveniles during spring and summer of either year, nor were there differences among these metrics in spring 2012 following 2011 fruit additions. Overall, there were no impacts to the short-term adult population dynamics for any species during fruit addition. We are led to believe that short-term pulses of fruit and (or) fruit-based carbohydrate abundance do little to influence temperate forest small-mammal populations.