The best thing for the duckling is a wild animal rehab center. They will raise it with other mallards, and when it's old enough to care for itself, they will release them as a group.

Sorry, but it's illegal to take in a wild bird.

I wouldn't hon. The wild duckling might carry a disease your domestics don't have any resistance to. I killed off a bunch of my brother's homing pigeons bringing a wild pigeon to live with them. I STILL feel horrid about it.

By bred I mean the ones you buy at a farm store during the season. We have our own flock, and we recently found a baby mallard. There was no sign of its mother or any other ducks. Right now he's got a stuffed animal and a mirror. Im afraid this wont be enough. He's the same size as the ones in the store, a bit bigger. Can we get another mallard for company?