Factors affecting fertility of red deer (Cervus elaphus) females in north-eastern Poland

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dc.contributor.advisor Jędrzejewska, Bogumiła
dc.contributor.author Borowik, Tomasz
dc.date.accessioned 2014-11-17T12:38:14Z
dc.date.available 2014-11-17T12:38:14Z
dc.date.issued 2014-11-17
dc.identifier.uri https://depotuw.ceon.pl/handle/item/905
dc.description.abstract Reproduction of mammalian females plays a key role in the population dynamics. Reproductive performance, however, depends on the broad set of extrinsic (weather conditions, food availability, predation, parasites) and intrinsic (population density, age of an individual, body condition, prior reproductive activity) factors. The highest significance is attributed to food availability, which is the main determinant of females’ body condition and their readiness for reproduction. Forage supply, on the other hand, is strongly dependent on the habitat quality and weather conditions. The main aims of this study, conducted in Augustów, Knyszyn and Białowieża Forests (north-eastern Poland) in 2006-2011, were to quantify the reproductive parameters of red deer (Cervus elaphus) females and to determine the factors affecting their fertility. Furthermore, I aimed at assessing the role of the reproductive input in the observed population dynamics under the existing mortality level. Finally, I conducted meta-analysis of the published data to compare some reproduction parameters of deer females from NE Poland with the available literature on other European populations. Reproduction parameters, body condition and the age of red deer females were determined based on 541 samples (female reproductive tracks and jaws) collected in the surveyed woodlands of NE Poland. Fertility of females was assessed by macroscopic examination of ovaries and uteri, while their age was determined based on tooth cementum. Body condition was described by two indices: dressed body mass and percentage of mandible marrow fat. In addition, information on the lactation status of hinds was obtained. Red deer population density in the studied forests was estimated based on drive counts. Environmental factors, which expressed habitat productivity and weather conditions were calculated in GIS from the available data sets (Corine Land Cover 2006, MODIS, GSMap). Finally, the association between reproductive parameters and intrinsic and extrinsic factors was established by incorporating of the statistical techniques including: regression models, correlations, analysis of variance (ANOVA), and generalized linear models (GLMs). Compared to other European populations, red deer in NE Poland occurred at relatively low densities (3.6-6.8 ind./km2), and hinds exhibited high reproductive potential, which was reflected in the high fertility rate (85%), low age of the first reproduction (1.5-year-olds) and lack of reproductive senescence. A clear negative effect of the population density on the hind fertility rate was evidenced at biogeographic scale. The strength of density-dependence in female fertility rates decreased with females’ age. At the population level in the studied woodlands, the body condition and the fertility rate of yearling females was significantly lower compared to older age classes (p < 0.001). Pregnant females had significantly higher body mass and percentage of mandible marrow fat than non-pregnant hinds (p < 0.001). At individual level, probability of hinds to be fertile was affected by their age and body condition. The positive effect of the body mass declined with the mother’s age, while the opposite relationship was proved for the mandible fat content – its effect increased with the age of hinds. The probability of fertility in yearlings was positively associated with the body mass. The probability of fertility in adult females (2-19-year-olds) increased with the growing percentage of marrow fat, and the effect of this factor increased with the female’s age. Environmental factors (low temperature and abundant precipitation in summer) could have a negative, indirect effect on fertility through the body condition of females. The foetus sex ratio was male-biased (1:0.68). Age-specific differences in the body condition of pregnant females showed a tendency that females in better body condition had more males among foetuses, which supported the Trivers-Willard hypothesis. The mortality rate of offspring in the first 6 months of lives was high (41%) and positively associated with the mother’s age (p = 0.02). This could have been the first sign of the reproductive senescence in mothers. Life expectancy of females at birth was low (4.3 years), which was most probably caused by a high level of mortality enforced by wolf (Canis lupus) and lynx (Lynx lynx), other natural factors and hunting harvest. The mortality rate was stable across the female age classes. Younger age classes (1-3 years old females) had the highest contribution to reproduction (46%). On average, females were supposed to produce more male than female offspring during the course of their lives. The reproductive potential of females balanced the losses imposed by mortality factors. Hence, the population of red deer in NE Poland is supposed to be stable. Findings of this study are expected to have practical significance in the deer management and decision making regarding hunting bags.
dc.description.abstract Celem badań, przeprowadzonych w Puszczach Augustowskiej, Knyszyńskiej i Białowieskiej (północno-wschodnia Polska) w latach 2006-2011, było określenie parametrów rozrodczych samic jelenia szlachetnego (Cervus elaphus) oraz czynników kształtujących ich płodność. Parametry rozrodcze określono w oparciu o analizę narządów rozrodczych samic. Łącznie we wszystkich objętych badaniami kompleksach leśnych zebrano 541 prób. W porównaniu z innymi europejskimi populacjami, jelenie w badanych kompleksach leśnych występowały w niskich zagęszczeniach, łanie wykazywały duży potencjał rozrodczy, który był wyrażony wysokim poziomem płodności (85%), wczesnym przystępowaniem do rozrodu (1,5-roczne samice) oraz brakiem spadku płodności z wiekiem. W skali biogeograficznej wykazano, iż poziom płodności łań był ujemnie skorelowany z zagęszczeniem populacji. W północno-wschodniej Polsce prawdopodobieństwo płodności samic wzrastało z ich wiekiem i kondycją. Czynniki środowiskowe (niskie temperatury i obfite opady latem) mogły mieć pośredni, negatywny wpływ na płodność poprzez kondycję samic. Wśród płodów wykazano większy udział płodów męskich (1:0.68). Zależne od wieku różnice w kondycji fizycznej samic wykazywały tendencję, w której łanie w lepszej kondycji fizycznej miały większy udział płodów męskich, co potwierdzałoby hipotezę Triversa Willarda. Poziom śmiertelności cieląt w pierwszych 6 miesiącach życia był wysoki (41%) i wzrastał wraz z wiekiem samic. Oczekiwana długość życia nowo narodzonych samic wynosiła 4,3 roku. Wykazano zbliżony, niezależny od wieku, poziom śmiertelności samic. Młode samice (1-3-letnie) miały największy wkład w rozrodczość populacji (46%). W latach badań rozrodczość bilansowała ubytki powodowane przez śmiertelność, dlatego przewiduje się stabilizację badanej populacji jeleni. Uzyskane wyniki mogą mieć praktyczne zastosowanie w zarządzaniu populacjami jelenia i planowaniu wielkości odstrzałów łowieckich.
dc.language.iso en
dc.rights info:eu-repo/semantics/restrictedAccess
dc.subject red deer
dc.subject fertility
dc.subject reproduction
dc.subject females
dc.subject body condition
dc.subject jeleń szlachetny
dc.subject płodność
dc.subject rozrodczość
dc.subject samice
dc.subject kondycja
dc.title Factors affecting fertility of red deer (Cervus elaphus) females in north-eastern Poland
dc.title.alternative Czynniki kształtujące płodność samic jelenia (Cervus elaphus) w północno-wschodniej Polsce
dc.type info:eu-repo/semantics/doctoralThesis
dc.description.eperson Tomasz Borowik
dc.contributor.department Wydział Biologii
dc.date.defence 2014-12-01

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