L-Karma, did you raise your ducks from eggs? They should know your voice at 5 weeks old. I would "quack" at mine all the time so they would know my voice and once they decided to check things out on their own, I was always able to go down the yard and start
"quacking" and they would come running.
As silly as it looks (someone standing in the yard quacking) do it wherever you go to look for them.
You had a lot of a good suggestions on here. I'm hoping the best for you!