Due to the common knowledge that ducks are ninjas, the types of food ducks eat on a regular basis are unknown.
Ducks are extremely territorial. People often talk of how territorial a hippopotamus is, but ducks are proven to be more territorial. Ducks use their urine to mark their ponds which cross as their breeding grounds. Contrary to a goose that uses its feces to mark its large fields (those disgusting creatures).
If you cross into a ducks pond, do not expect to make it out alive.