An Instrumented Golden Eagle’s (Aquila chrysaetos) Long-Distance Flight Behavior

SIMPLE SUMMARY: All large birds have devised ways to save on the costly energy demands of flight. Geese, which form into a precise V formation, are a familiar example. Current measurements from GPS instrumentation attached to birds provide the exact location of the bird at every second of its flight. These measurements are transmitted during migration. An analysis of such data for a single 105 km (~70 mile) segment of a golden eagle’s flight illustrates how the bird makes use of atmospheric waves near 2000 m above the ground to repetitively climb 100s of meters while circling, followed by long glides to advance along its migratory route. From this height, in sixteen circling/gliding episodes, the eagle covers more than 100 km by harvesting atmospheric wave energy. Such details of a single bird’s 2 h segment of flight provide insight into how a soaring bird can cross continents and oceans, and even rise over the world’s highest mountains. ABSTRACT: One-second-processed three-dimensional position observations transmitted from an instrumented golden eagle were used to determine the detailed long-range flight behavior of the bird. Once elevated from the surface, the eagle systematically used atmospheric gravity waves, first to gain altitude, and then, in multiple sequential glides, to cover over 100 km with a minimum expenditure of its metabolic energy.