Plasma cortisol as an indicator of stress due to capture and translocation in wildlife species.

Plasma cortisol concentrations were determined by radioimmunoassay in 712 individual animals of 18 wildlife species after either physical or chemical restraint, tranquillisation or trauma, in order to define baseline values and to assess the possibility of using cortisol as an indicator of stress. The cortisol levels appeared to rise after capture in all the species examined except the Cape buffalo. On the basis of the plasma cortisol levels, chemical capture was less stressful than physical restraint. Animals which were tranquillised had lower than 'normal' cortisol levels, whereas animals that had suffered trauma or which died after they were captured had higher than normal cortisol levels.