NM, I found out all I need to know from my friend. Thanks!
Edited by goldfinches - 4/15/16 at 8:45pm
There is something called the Migratory Bird Act that you need to know about - only people licensed to do so (if I understand correctly) can legally keep migratory birds, and I believe Mallards are in that category.
So, you may need to find a waterfowl rehabber in your area...