Double-crested Cormorants such as this one may often be seen spreading their wings, and it’s generally assumed that the purpose is to get the wings dry. Unlike most other birds, cormorants’ feathers aren’t normally oiled up enough to repel water. Cormorants’ wings get wet. It’s thought that wet wings give the birds an advantage under water, where they do their hunting. They’re very fast and maneuverable, and eat whatever species is available.
However, the theory that cormorants spread their wings to dry them doesn’t convince everyone. Researchers have noticed that cormorants will stand and spread their wings on days without sun and even in the rain. There’s speculation that the real purpose is to stretch the flight muscles.
Cormorants do have the oil gland at the base of their wings near the tail, and they apply its secretions not only to their feathers but also to their legs and feet. Photographer Emilie Keas, who took the photo above, caught the bird accessing its preen gland, photo below left. She also got a picture of the bird running one of its flight feathers through its bill, below right.
These are very nice photos. Thank you, Emilie, for sharing.