Here are some often repeated remedies. However ducks are like people with individual likes and dislikes. What might terrify one duck could be "ho-hum" to another.
- a plastic owlis usuallyowl: usually available at birding stores, sometimes outdoor/hunting stores. Get the better quality ones with a head that moves or the deluxe versions with wings that move. (I'm not making this up!)
- any bright object like CD's on a string or bright reflective streamers
- as a temporary solution string fishing line across your yard near where they land above head height. All birds don't like to hit things when they are landing and fishing line will not hurt them, only surprise them.