Fuel storage and use in migrant and resident birds

Migration is an endurance event that requires proper training and fuel. While human athletes that fail to eat optimally before endurance competitions may cost themselves a chance at medaling or qualifying for future events, wild animals that fail to fuel themselves properly before undertaking migrations risk far more consequential costs like missed breeding opportunities or death. Compared to proteins or carbohydrates, fat contains approximately eight times the energy per unit mass, making stored fat the most efficient fuel for migrating birds. Previous studies suggest that migrating birds alter their energy intake as well as their dietary composition and food preferences in preparation for migration, suggesting that they have both metabolic as well as behavioral control over the amount and composition of fat that they accumulate. We study migration-related fatty acid metabolism in the Common blackbird (Turdus merula) consisting of individuals from fully migratory, partially migratory, and resident populations across Europe.