How Migrants Get There: Migratory Performance and Orientation

L ong-distance migration is the process of trans- portation between widely separated areas, typically divided in cycles of energy accumulation (fueling) and movement toward the goal. These cycles are repeated until the goal is reached. At this level of analysis, migration is deceptively simple. In reality, however, migration is a complex process that offers an ideal study system for the evolutionary biologist, as it involves specific adaptations involving morphology and physiology for efficient energy accumulation and locomotion, and behavioral adaptations for optimal use of external factors (winds, currents, orientation cues). Together these adaptations define the migration syndrome (i.e., the suite of characters that helps the animal to migrate more effectively than a resident). The experimental and modeling toolkit available to study migration has expanded dramatically in recent years, involving cross-disciplinary approaches and methods such as molecular genetics, isotope analyses, magnetic resonance imaging, ultrasound, electromagnetic coils, and wind tunnels.