Stress and its evaluation in wild herbivores

Internal or external stimulus that instigates a biological response in excess to normal is known as stress (Yaribeygi et al., 2017). Stressors are environmental factors that stimulate abnormal homeostatic, physiological and behavioural responses. Different stressors are anthropogenic activities; adverse climatic conditions like drought, sudden rain or wind, excessive fatigue due to predator or pain (Radostits et al., 2007). In response to stress, the corticotropin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH), and other stress mediators are released (Carrasco and Van de Kar, 2003). These hormones are metabolised by digestive enzymes in liver and gut and can be quantified by measuring faecal cortisol metabolite concentration (FCM). It is a non- invasive and cost- effective technique (Hadinger et al., 2015). This short review aims to discuss the different studies involving wild animals and evaluation of stress in wild animals.