Reproductive biology of the European badger (Meles meles) : Endocrinological insights into lifetime reproductive events, strategies and cub development in response to ecological factors
Keywords: Urinary Hormone Monitoring
European Badger
Oestradiol
Superfoetation
Post Reproductive Life Span
Climatic Factors
Social Factors
Reproductive Status
Sexual Size Dimorphism
Mating Strategies
Reproductive Cessation
Developmental Heterochrony
Anaesthetic Adverse Effects
Anaesthesia
Oestrone
Alternative Reproductive Strategies
Somatic Condition
Growth Patterns
Urine Metabolites
Seizures
Phenotipic Quality
Weather
External Genitalia Condition
Sex Steroids
Delayed Implantation
Oestrogen
Puberty
Testosterone

Knowledge of reproductive adaptions and physiological mechanisms are essential in wildlife conservation as they impact species survival. As markers of bodily functions, hormones mirror reproductive activity and reveal baseline information including reproductive cycles and strategies, lifetime reproductive events such as puberty and senescence, as well as responses to ecological factors, which are all profound factors of wildlife population growth. In this thesis, the reproductive biology of the European badger (Meles meles) is examined by utilising endocrinological measures with complementary somatic and ecological data. Research chapter I establishes endocinological mechanisms of the flexible delayed implantation and superfoetation mating strategy, where number of additional mating seasons varies with population density across badger geographical range. Research chapter II demonstrates that despite hormone levels and external genitalia morphology (EGM) showing similar seasonal patterns, EGM in males is a reliable indicator of reproductive status only during the mating season, while in females EGM is a less precise proxy. Research chapter III reveals that asynchronous timing in attaining minimum body size, required for sexual maturity, results in two heterochronous phenotypes (early- and late- developers) in male cubs (less evident in females), while Research chapter IV showcases the decline in sex-steroid levels and somatic condition with age, leading to a post-reproductive lifespan (PRLS), while also showing two reproductive phenotypes (high and low hormone levels) in older individuals of both sexes. Research chapter V demonstrates that sexual selection is unlikely to be the driving force for sexual size dimorphism in badgers, but social and environmental factors, as well as endocrinological mechanisms, affecting juvenile diverging growth patterns and end body sizes are likely the primary physiological process of this phenomenon. Research chapter VI illustrates that ecological changes can be reflected in hormone levels and the regulation of these changes differs between sexes, likely linked to their respective reproductive strategies. Research chapter VII establishes that urinary metabolite measurement may reliably assess endocrine function in badgers as a non-invasive technique, especially in males. Collectively, these research chapters give a comprehensive understanding of the badger’s reproductive processes and how it interacts with ecological factors.