Can ducks and pheasants be raised together?

The weirdest thing happened the other day. A wild baby mallard (about a week old) wandered onto my driveway. The mother was no where to be found. So I took the duckling and gave him a home. It has been 2 days now and he (or she?) is doing great. I would like to get the little guy a buddy or 2 but all my local feed stores are out of ducklings. I was wondering if I could buy a couple pheasant/ chicken chicks about the same age and raise them together. Would this cause a problem? Please fill me in on any experience or info that any of you may have. I feel bad for the little duckling as he gets lonely when I leave him. Thanks in advance for the help!