I don't have ducks, but that's a great photo! We introduced our chicks to our Labradors as soon as we brought them home. The chicks were in a tote on the front porch, so every day, several times a day I'd stand there with the dogs and just talk to them and pet them while holding a chick so they could sniff them. Eventually they learned that these weren't for eating, and they never bother the chickens. It's important to spend time doing these things.
My ducks are my favorites. I let them out of their run when I am in the yard. They run down to the stream for a quick swim and then follow me every where. They are always on my feet and I trip over them. It's actually endearing.