This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
Each autumn and spring a rush of wings fill the night skies as birds migrate between distinct locations for breeding and the other for over-winter survival. However, recent reports indicate that the numbers of migratory species are rapidly declining worldwide. Reasons for these declines have been attributed in general to global environmental change but few specifics are known. Even though bird migration has been appreciated for hundreds of years, little is understood of how environmental conditions influence regulation of the physiological and behavioral mechanisms of migration. Another enigma is that even though spring and autumn migrations appear similar in distance and terrain covered, the climatic conditions and physiological and behavioral states of migrants in the two seasons differ. The studies proposed are designed to determine the mechanisms of both spring and autumn migrations in a long-distance migrant, the Gambel's White-crowned Sparrow. Comparisons are drawn with a close relative and non-migrant, Nuttalls White-crown Sparrow. Intraspecific comparisons of this nature are rare and vital for determining the adaptations of migrants. Specifically, how do such factors such as photoperiod (day length) affect the behavior, physiology and biochemical changes required to migrate long distances (6000 km)? For example, migrants must increase appetite to achieve a temporary state of obesity and increase aerobic capacity and endurance of flight muscles, etc. to complete each migratory bout. Studies will test how the spring increase in day length affects feeding, fattening and skeletal and heart muscles. Comparisons will be run in autumn, when day length is declining. Results from these studies may provide intricate clues for determining how the environment affects migrants in order to slow or even prevent further loss of this remarkable adaptation.
