Differences in flight and heart muscle mass among geese, dabbling ducks, and diving ducks relative to habitat use

Abstract

Geese, dabbling ducks, and diving ducks differ in their ability to take off vertically when initiating flight. For three species of goose (N = 127), five species of dabbling ducks (N = 89), and eight species of diving ducks (N = 128), the masses of pectoralis, supracoracoideus, and heart muscles, and two indices of wing form (wing loading and aspect ratio) were measured. Differences in take-off ability among the groups were associated with differences in the mass, i.e., the potential power output, of the flight and heart muscles, and in wing form. Dabbling ducks had the greatest relative mass of flight muscles (p < 0.0001), lowest wing loading, and highest aspect ratio, and elevate almost vertically from the water's surface when taking off. Conversely, diving ducks had the smallest flight muscles, highest wing loading, and smallest aspect ratio, and begin flight by running over the surface of the water to gain sufficient forward velocity. Geese were intermediate between dabbling ducks and diving ducks for these three characteristics. Diving ducks however, had the largest heart mass of the three groups (p < 0.0024). Among diving ducks, heart size increased with the foraging depth of each species. It is suggested that heart size in diving ducks reflects a response to diving superimposed upon the demands for flight.