Faecal Glucocorticoid Metabolites and H/L Ratio are Related Markers of Stress in Semi-Captive Asian Timber Elephants

Animals are kept in captivity for various reasons, but species with a slower pace of lifemay adapt to captive environments less easily, leading to welfare concerns and the need to assessstress reliably in order to develop effective interventions. Our aim was to assess welfare of semicaptivetimber elephants from Myanmar by investigating the relationship between twophysiological markers of stress commonly used as proxies for welfare, faecal glucocorticoidmetabolite concentrations (FGM) and heterophil/lymphocyte ratios (H/L), and link these measuresto changes in body condition (determined by body weight). We further assessed how robustly thesetwo markers of stress performed in animals of different age or sex, or in different ecological contexts.We measured FGM concentrations and H/L ratios between 2016 and 2018 from 316 samples of 75females and 49 males ranging in age from 4 to 68. We found a positive and consistent link betweenFGMs and H/L ratios in Asian elephants, irrespective of their sex, age, or ecological context. Ourresults will help to inform managers of (semi-) captive elephants about using heterophil/lymphocyteratio data from blood smears on site as a potentially cheaper and faster alternative to determiningstress than measuring faecal glucocorticoid metabolite concentrations in the laboratory.