Animals are kept in captivity for various reasons, but species with a slower pace of life
may adapt to captive environments less easily, leading to welfare concerns and the need to assess
stress reliably in order to develop effective interventions. Our aim was to assess welfare of semicaptive
timber elephants from Myanmar by investigating the relationship between two
physiological markers of stress commonly used as proxies for welfare, faecal glucocorticoid
metabolite concentrations (FGM) and heterophil/lymphocyte ratios (H/L), and link these measures
to changes in body condition (determined by body weight). We further assessed how robustly these
two 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 75
females and 49 males ranging in age from 4 to 68. We found a positive and consistent link between
FGMs and H/L ratios in Asian elephants, irrespective of their sex, age, or ecological context. Our
results will help to inform managers of (semi-) captive elephants about using heterophil/lymphocyte
ratio data from blood smears on site as a potentially cheaper and faster alternative to determining
stress than measuring faecal glucocorticoid metabolite concentrations in the laboratory.