Developmental stage shapes the realized energy landscape for a flight specialist

Abstract

The heterogeneity of the physical environment determines the cost of transport for animals, shaping their energy landscape. Animals respond to this energy landscape by adjusting their distribution and movement to maximize gains and reduce movement costs. Much of our current knowledge about energy landscape dynamics focuses on factors external to the animal, particularly the spatio-temporal variations of the environment. However, an animal’s internal state can significantly impact its ability to perceive and utilize the available energy within the landscape, giving rise to an "individual energy landscape". Here we show that an individual’s energy landscape varies along the ontogenetic axis. Locomotor and cognitive capabilities of individuals change over time, especially during the early life stages. We investigate the development of the energy landscape during ontogeny in the Central European alpine population of the golden eagleAquila chrysaetos, a large predator that requires negotiating the physical environment to achieve energy-efficient soaring flight. We constructed weekly energy landscapes using environmental features for 55 juvenile golden eagles and demonstrate that energetic costs of traversing the landscape decreased as the birds aged. In fact, the potentially flyable area within the Alpine region increased 2,170-fold during their first three years of independence. Our work contributes to achieving a predictive understanding of animal movement behaviors by presenting ontogeny as a mechanism shaping the individual energy landscape.