I adopted 3 abandoned 1-year-old adult ducks 6 years ago. They were very scared of me, and when they saw me they would run in the other direction and huddle against the furthest wall.
Within months I tamed them to come when I called, eat from my hands, and follow me. One would even jump up into my lap. She didn't want me to touch her, she just wanted to stand on me. All three actively enjoyed being near me. If they saw a scary hawk fly over they ran to my feet. As time has passed they have become more and more comfortable.
I can touch them a little bit now, but they don't enjoy it so I don't do it unless I need to for a medical reason. My ducks also feel stressed being separated from their flock members so I don't do that, either, unless I need to for vet visits.
I'm happy to share more about how I helped my ducks become tamed.