They quickly became too big and aggressive for him so we moved them out and some more tiny mallards in. This continued on for a while. Shortly after the arrival of the common merganser, a wood duck was admitted. He was found alone in someone's yard, but had no apparent injuries. He was newly hatched.
Wood ducks are a difficult species to keep alive.
First, they need siblings. When they are raised alone they get depressed and die. Second, they are escape artists and they can climb. Lastly, they have slightly different nutritional needs than mallards, so keeping them with the mallards can be tricky. Since the merganser was eating meal worms and small minnows right out of our hands at that point, we decided to put the wood duck and the merganser together.