It’s obvious where that expression, “like water off a duck’s back” came from. Duck feathers shed water amazingly well — their plumage seems almost impenetrable.
No doubt part of staying warm in the chill winter temperatures and winds is staying dry, and duck plumage is intended to do just that. Not only are the feathers incredibly dense, laid down in overlapping layers in feather tracts, but they are coated with a waxy residue from a gland at the base of the ducks tail that waterproofs them.
But what about those bare feet, exposed to near freezing water temperatures and standing on cold rocks or ice or snow for hours on end? Feet don’t shed water, just the feathers.
This drake has just climbed out of the water, and is standing on ice, not something we would be comfortable doing (barefoot). What happens when we reach for ice cubes in the freezer with wet fingers? The ice sticks to our fingers and is difficult to remove without losing some skin in the process. So how do ducks keep their wet feet from sticking to the ice?
The secret is to maintain very cold toes that are the same temperature as the surface on which the duck stands or walks. This is achieved by having arterial blood going to the foot run in parallel with the vein that is bringing cold blood back from the foot — making a heat exchange unit that promotes cooling the extremities while preserving the warmth of the body core. Engineers have used this principle in the design of heaters and air conditioners, among many other uses.