East African pastoralists exploit livestock in a variety of different environments, all characterized by drastic seasonality. Pastoralists adjust to seasonality in food supply by temporally exploiting different species of livestock, by moving livestock and people, and by adjusting human population to available resources. This study is predicted on the hypotheses that (1) patterns of pastoral food procurement are aimed at achieving energy homeostasis under pressure of environmental variability and that (2) this goal of energy homeostasis requires different strategies in different ecosystems. These propositions will be tested by comparing food procurement patterns among three groups, the Rendille and Turkana of northern Kenya and the Borana of southern Ethiopia. The Rendille herd camels in a dry area, the Borana exploit cattle in mesic mountains, while the Turkana (in an intermediate environment) exploit five species of livestock. Dr. Kathleen A. Galvin will use field data and literature sources to assess the success of these human groups in maintaining energy balances on a seasonal basis despite fluctuations in food supply. A simulation model will be used to compare and integrate energetics data from these pastoral populations. The project will elucidate interactions between environment, human strategies and ecosystem energetics within the framework of systems ecology and ecological anthropology. The host institution for the one-year postdoctoral fellowship activity is Colorado State University.