Non-invasive monitoring of a stress biomarker in captive and free-roaming tigers in South Africa

Abstract

The tiger (Panthera tigris) is among the most endangered apex predators in the world and is believed to be the second-most trafficked animal on Earth, after pangolins. In the last century their habitats have been reduced by 95% and their wild populations decimated. They continue to face threats such as habitat loss, persecution, and poaching and unless all of these, and more, are addressed, the future of wild tigers is not guaranteed. However, captive tiger populations seem to do relatively well, outnumbering their wild counterparts hugely. There are many different conservation efforts currently being undertaken, both in the wild and captivity, but all factors, both biological and anthropogenic, that affect their welfare require investigation. The data chapter of this dissertation focused on examining factors that impact the well-being of captive tigers in South Africa in regards to their adrenocortical stress response and how this compared to both captive and wild Indian tigers. Faecal glucocorticoid metabolite (fGCM) concentrations were measured at eight different study locations; five in South Africa and three in India. In South Africa, three sites were zoos, one was a pet tiger held in a backyard enclosure and one site was a reserve were the tigers were “re-wilded” and allowed to live with little interference from humans. Location, season, sex, and level of exposure to humans was investigated and then these results were compared to those of tigers living in their native country of India; both in the wild and captivity. The data showed no difference in fGCM concentrations between Indian and South African tigers, and while season and sex does not seem to play a role in altering fGCM concentrations, certain locations and higher levels of public exposure did lead to significantly higher fGCM concentrations. This data are the first to examine the adrenocortical stress response of captive and re-wilded tigers in South Africa with a direct comparison to wild and captive individuals in India. The feasibility of using fGCMs as a non-invasive method to monitor adrenocortical activity is demonstrated, as well as the value of understanding possible stressors that may impact the well-being of tigers in a captive, semi-wild, or wild setting.