The effects of energetic expenditure tactics and life-history variability on European badger (Meles meles) ecology

Wild animals have evolved a diverse range of energy-budgeting tactics to cope in situ with rapid environmental change. My thesis investigates these tactics and their underlying mechanisms in a population of wild European badgers (Meles meles): 1) over the course of an individual’s lifetime and 2) in response to fine-scale changes in energetic context. Chapter 1 derives a novel minimum number alive abundance estimator, incorporating variable capture efficiency to more accurately quantify changing social context for subsequent analyses. Chapter 2 exposes how changing population metrics and weather drive sex-specific life-history responses, producing diverse co-occurring paces-of-life and potentially contributing to substantial sex ratio skew at higher densities. Chapter 3 uncovers a threshold-bounded relationship between body condition and survival probability, whereby most badgers exhibit flexible somatic phenotypes within what I term an “energetic safe zone”; adverse weather and life-history risk factors can tip individuals over the threshold, but a minority of high-quality individuals exhibit high reproduction probability and lower mortality risk despite reduced body condition. Chapter 4 uses 3D printing to streamline production and reusability of bespoke multi-sensor collars, enabling simultaneous fine-scale quantification of overall dynamic body acceleration (ODBA, measuring mechanical energy expenditure) for multiple individuals. Chapter 5 applies this technology and finds season-specific fine-scale activity responses to prevailing weather conditions, according to individual energetic context; in particular, low body condition constrains energetic tactics. Chapter 6 combines ODBA with quantification of daily energy expenditure (DEE) using doubly-labelled water, demonstrating that individuals expend energy differently under the same conditions; ODBA/DEE, measuring proportional energy expenditure on activity, correlated negatively with next-season body condition. The range of energetic expenditure tactics sustained in this population support the existence of adaptive heterogeneity. I present an argument predicated on Jensen’s Inequality for the maintenance of this diversity, and reflect on implications for resilience to ongoing anthropogenic change.