Lee, excellent point and good advice. We made at least a dozen or more changes in every aspect we had control over. I went from 4 doz to 1 dozen decoys. Most use 2 to 3 doz plastic decoys. I use fully flocked black ducks and or mallards. Went from three robos to none. Changed blind locations, decoy spread pattern, calling - no calling. Probably should have tried only 2-3 decoys. Thought area too large to not use any since they had been coming in to rest not get food.
Most ducks were gadwall and I didn't have any gadwall decoys if that would have made a difference. On the other side of the dike were several thousand birds on rough open water that the mallards and pintails were drawn to.
We had watched these birds drop into our marsh the day
before.
Your point that it may have just been the wary ducks which had been beaten up for 2 weeks seems well founded.
Thanks for your input as it really helps to keep my sanity.