Wing- and Tail-flapping in Anhingas: a Possible Method for Drying in the Absence of Sun

Anhingas (Anhinga anhinga) commonly spread their wings and perch in the sun, ostensibly to dry wettable feathers (Bent 1922, Life histories of North American Petrels and Pelicans and their allies, Washington,U .S. Natl. Mus. Bull. 230). The flight feathers themselves appear not to become appreciably wet, but the body feathers absorb water that helps reduce the submerged bird’s buoyancy

ANN M. FRANCIS, The Auk 98: 834