Ducks are endowed wih an abundance of feathers, especially on the underside of their bodies. They can swim in very cold water and remain warm. Soft down feathers close to the skin are covered by larger outer feathers. Several times a day, ducks preen and oil these feathers. A feather conditioner is used from a hidden oil gland located on the top of the tail base. As the duck preens, they squeeze the oil gland with their bill and spread it onto the feathers. Contrary to popular belief, this oil does not "water proof" a duck nor it's ducklings. What does ? Click here to get the answer. If you see feathers missing or falling out they maybe molting  or visitThe ducks new clothes
Ducks have long pointed narrow wings-except muscovies, theirs are broad and rounded. Most domestic breeds can not fly. The following can fly: Muscovy, Call, East Indies, Mallards.
Muscovy has a 4 to 6 inch squarish tail. Other ducks have shorter pointed tails. Except for Muscovy, adult males have curled, C shaped, feathers on the top center of their tail.
Long and wide, the bill is used for collecting food from water, catching flying bugs and rooting out underground goodies. Nostrils are located near the head, this allows the duck to dabble (make mud pies) in shallow water and breath at the same time. Duck hens that have yellow or orange bills may turn darker, get streaks or spots when they begin to lay. Not to worry, I hear that is a sign of a high egg producer. The protrusion hanging over end of the bill is called a nail. This is used to nip roots and such as they dabble.
Don't be fooled by the size of the eyes. Ducks have excellent vision. Due to the location of their eyes they can see almost 365 degrees without moving their head. This way they keep a constant lookout for danger. Ducks can also see a hawk in the sky before you can.
FEET and LEGS
The webbed toes and short legs are not very fast on land. These skilled swimmers rather escape danger by way of water. Ducks legs are easily injured...it is advisable to catch or pick them up by the neck and body
The back should be long and straight. Some of the larger breed have a tendency toward arched backs. The humped back can be a problem since ducks with this fault have low fertility or are sterile. When selecting breeders, avoid ducks with excessive curved backs.
Ducks that are heavily feed and selected for large size and fast growth often develope a keel. This is a fold of skin that hangs from the front of the underbody and in some cases may run the entire length of the body and touch the ground as the bird walks. Well developed keel is a feature in Rouens and Aylesburies, it is not preferred on any other breed.