Monitoring European badger (Meles meles) reproduction under evolving bovine tuberculosis management in Ireland

Abstract

Wildlife disease management often relies on altering population abundance and density to reduce the susceptible host population. Understanding the vital rates and ecology that influence wildlife population dynamics is important for assessing the outcomes of management policies. European badgers (Meles meles) in Ireland have historically been managed for bovine tuberculosis (TB) using culling, but are now being vaccinated instead. We used data from 6847 badgers submitted for postmortem examination from 2016 to 2018 to inform population monitoring of badgers under this management change. Female reproductive status varied strongly by month, and a considerable proportion (25–40%) of females had evidence of premature cessation of lactation. Teat lengths may offer a crude guideline for rapid antemortem assessment of probable reproductive status. Body weight for males and females declined throughout the capture period, and we report reference ranges for normal male and female body weight during each month. Increasing body weight was associated with an increased odds of pregnancy (OR 2.52, 95% CI 2.20–2.93, p < 0.001). Prior capturing at the sett where a badger was captured did not affect the odds of pregnancy (OR = 0.99, 95% CI 0.96–1.03, p = 0.77) or influence litter size (β = − 0.0012, SE = 0.014, p = 0.93). Assessing changes in badger reproduction will ensure that management is adapted for a badger population likely to expand and contribute to a successful TB eradication program in Ireland.