Androgen Regulation of Avian Premigratory Hyperphagia and Fattening: From Eco-Physiology to Neuroendocrinology

In many high latitude-breeding avian species, reproductive and wintering seasons are separated by migratory periods that involve dramatic physiological and behavioral adjustments such as hyperphagia and fat deposition. The endocrine mechanisms responsible for these adjustments have been extensively studied, yet remain only partly understood. The currently available information indicates that food consumption and/or fattening can be experimentally modulated by multiple hormones including testosterone, prolactin, glucocorticoids, and opioids. These hormones may control migratory functions through mutual interactions rather than independently. Little is known, however, concerning the nature of these interactions and their relative importance in the control of annual cycles in natural conditions. This paper focuses on the role of gonadal androgens in the control of migratory functions, and it summarizes the information which is available on the physiological and behavioral interactions between these androgens and other hormones.