>Maybe a shock collar(I know I'm going to get my fanny burnt
>for this)on low voltage that anytime he gets near them..give him alittle
>jolt.

   Or you could try one of those water guns (or hose) that has a big
powerful stream and squirt the dog when he starts to go after the
ducks.  When he gets so he is running the ducks, quickly give a command
such as "Get Back" or "Leave It", then a squirt with the water if he
doesn't listen.  (If you have kids they will love to help with this part of the
training.)  As we went along we tried not to actually squirt the dog but for a
stream of water landing on the ground in front of the dog's nose,
keeping the dog from making contact with the ducks.  I think
it was more the element of  surprise that backed the dog off.  Be sure to
praise the dog when he backs off.
    It only took Brandy (7 month old, English Shepherd) about a week and
a half of this treatment before she decided chasing the ducks, chickens, and
cats was not allowed here.  Once she figured it out we could trust her not to
bother them and had no more dead ducks.
      Marianne