programs to increase nutrition, and this also increases the number of deer that can be sustained in a particular area. I am investigating whether these high density populations, where food sources are not limiting, are susceptible to elevated stress levels.

Stress is often overlooked as a significant cost to wildlife, even though it can cause substantial changes in the physiological profile of an individual. When an organism perceives a threat, the adrenal cortex secretes glucocorticoids. The stress response enables an animal to cope with a stressful situation by preparing energynecessary for the response and minimizing energy expenditure by other bodily tissues that are not needed for immediate survival. Chronic stress causes prolonged glucocorticoid activity which can have serious impacts on individuals. Prolonged stress continually diverts energy away from processes that are not required for immediate survival, such as growth, reproduction, and immune system responses. Although our understanding of the effects of stress on wildlife is still in its infancy, research to date suggests that there can be substantial physiological and/or long-term effects. Red deer (Cervus elaphus) maintained in high density, potentially stressful environments have been shown to have lower growth rates than those kept in low density, less stressful environments. Ozoga and Verme (1982) noted that as the population density of a supplementally-fed white-tailed deer herd increased, the productivity of yearling does decreased. They hypothesized that harassment by numerous males during the breeding season caused an energy deficiency in yearling does that led to lowered productivity. Stressful situations, such as fighting in mice (Mus musculus) and rats (Rattus norvegicus), have also been shown to impari immune system health. Although the stress response is an important survival mechanism that has evolved to improve an individual’s ability to cope with stressful events, prolonged (chronic) stress responses can potentially have detrimental consequences.

Recently, a new, non-invasive technique has been developed to monitor stress levels in free-ranging wildlife populations. This technique involves measuring stress hormones in voided feces, which are relatively easy to collect and can be obtained without disturbing the study animals. Glucocorticoids, hormones released during times of stress, are excreted in feces and urine in concentrations relative to concentrations that are circulating in the blood. By extracting these hormones, I can determine how stress levels fluctuate throughout the year and how they differ between populations.