Even Mallards that are bought from feed store or hatchery have never been in the wild[their parents] they are just as domesticated as a pekin or runner. so they need to be taken care of just like any animals that have never been in the wild. What breed do you have? I have Muscovy and all but my oldest drake have been raised right here. My drake was a dumptee in our river and we adopted him, he is 9yrs old. he would have never lived that long if we had left him to fend for himself on the river. matter of fact the other ducks that were with him are all gone. Good to hear it wasn't something you wanted to do. please let us know how your duckling gets along.
