An animal's antioxidant capacity is measured by its ability to quench reactive oxygen species (ROS). During everyday metabolism, antioxidants and ROS are in equilibrium with one another. In times of stress, an animal produces more ROS and therefore uses its antioxidant capacity more readily in order to maintain this equilibrium. When the production of ROS exceeds the antioxidant capacity, an animal will experience extensive oxidative stress, which can ultimately affect that animal's health. During experimental study of wild animals, it is often necessary to capture them for a short period of time. In order to obtain a measurement of the effects of short-term captivity on oxidative capacity in wild animals, a population of southern hairy-nosed wombats (Lasiorhinus latifrons) in Swan Reach, South Australia (34.57°S, 139.60°E), was studied. To assess the variation in antioxidant capacity, two assays, the ferric reducing ability of plasma and the trolox equivalent antioxidant capacity, were performed. A third assay, thiobarbituric acid reactive substances, was used to measure the effects of ROS. Measurements of the specific antioxidants uric acid, ascorbic acid, retinol, α-tocopherol, and superoxide dismutase were also performed. The biochemical parameters albumin, total protein, cholinesterase, creatinine, and urea were measured as indicators for health. Results showed a significant reduction in antioxidant capacity during the overnight period of captivity.