Why do ducks have feathers?

Uh because "Ducks and geese rely on their remarkable plumage for many things, but especially to keep warm. ..."

Explanation:

Not my words lol <3

Ducks use their feathers to stay warm in the cold seasons. In the cold, wintry conditions feathers are a duck's first defense. Waterfowl have three types of feathers: contour, flight, and down. Contour feathers collectively serve as a protective outer shell. Each feather is composed of a central shaft with a continuous series of paired vanes that line up on opposite sides of the shaft. Tightly interlocking barbules line the edge of each vane and hold them together like Velcro. They overlap one another much like shingles on a roof, forming an almost impenetrable barrier to wind and moisture. Feathers are also held in place by specialized muscles just under the skin. Using these muscles waterfowl can fluff up their feathers and move them back into position at will.

we need to see the paragraphs in order to answer this.