Hey, I am just checking--I have a wild Mallard that was attacked as a baby by a neighborhood dog while mama took the ducklings for a stroll. She has grown up and her primary flight feathers are coming in--when she is fully feathered, I am planning to release her back into a nearby park. I hope your advice would be different for me since she is a wild duck and can fly? She definitely does not love people--I am planning to have her start spending her days foraging in the backyard before I turn her loose. I just don't think she will be happy with us, (although we are getting a few domestic ducks soon) and I have done research and found that it isn't legal to keep her anyway as she is not a hatchery Mallard.
I actually believe that the law prohibits keeping animals taken from the wild as soon as they do no longer need human care.
Giving her time to adjust to outside conditions is a good idea. When you release her, look for other mallards, they will be helpful as guides in the new environment. What were her life conditions so far? Did she have plenty of water to swim and bathe?