Incorporating energetics in the annual cycle of migratory animals

Judy Shamoun-Baranes

University of Amsterdam, The Netherlands

Seasonal migration is often considered energetically costly. Migration may require any combination of physiological, morphological and behavioural adaptations to sustain persistent and seasonally directional movements typical of migration. Yet migration is only a part of the annual cycle of an animal. Multi-sensor bio-logging data, annotated with environmental information create exciting opportunities for studying the daily energetics, activity and modes of locomotion of migratory animals throughout the annual cycle, rather than studying migration in isolation.  We can study when in the annual cycle and where in space energetic bottlenecks may arise and use the information to understand how locomotion and environment interact to shape the energetic costs of migratory lifestyles. I use our work on daily energy expenditure of Lesser Black Backed Gulls (Larus fuscus), omnivorous seabirds with diverse locomotion, foraging and migration strategies, to demonstrate the potential for this type of research. Within the constraints of the annual cycle, we found that daily activity patterns can vary significantly among individuals. Yet when aggregated among different migration strategies, annual energy expenditure is similar. Diverse challenges encountered in data collection and model development may be relevant across taxa. Finally, I hope to stimulate discussion on the added value of combining energetics and locomotion to better understand the adaptive capacity of migratory animals.