“Like water off a duck’s back”, goes the common expression. When raindrops hit the “waterproof” feathers on a duck, they bead up and do not penetrate the feathers. How does this work?

Bird feathers aren’t naturally waterproof. But birds can make them water resistant by applying waxes from their preen glands. You may have watched a pet parrot grooming its own feathers – the bird will alternately rub its head against the base of its tail, and against its other feathers. It is depositing waxy, water-resistant oils found in the preen gland (at the tail base) onto the other feathers.

Birds also have a dusty powder in their feathers. This powder comes from special feathers called “powderdowns”, which are constantly disintegrating into waterproof powder. This powder adds to the water-resistant quality of feathers.

It is essential for birds like ducks to constantly preen their feathers to keep them in good shape, and to keep distributing these waterproof oils and powders.

Seabirds that dive underwater have particularly dense feathers, which also helps water from penetrating through the feathers to the bird’s body.