Wild animals are dependent on seasonal changes in the quality and availability of food. The area in which they range plays a vital role in determining the quality of food found and thereby the body condition of the animal during the year (Poole 1989). Changes in body condition might have an influence on the behaviour of an animal, possibly by physiologically effects e.g. changes in circulating glucocorticoid concentrations. In rats for example it has been shown that a reduction in dietary energy causes an elevated level of urinary corticosterone (May, 1986). It has also been demonstrated that a reduction in body weight due to limited access to water and food causes elevated glucocorticoid levels in female elephants(Foley et al. 2001).

Generally speaking, an elevation of glucocorticoid levels is caused by release of corticotrophin-releasing hormone (CRH) from the hypothalamus. The CRH triggers the anterior pituitary to release adrenocorticotropic hormone (ACTH). ACTH, in turn, stimulates the adrenal gland to secrete glucocorticoids such as cortisol (Fieß, 1999). A possible explanation for the rise in circulating glucocorticoid concentrations might be that a diet low in energy represents a form of physiological stress (Foley et al., 2001). However, to properly understand the link between changes in circulating glucocorticoid concentrations and qualitative and quantitative changes in food intake, it is necessary to know more about the circumstances which trigger reduced feeding / dietary intake.