Concerned about the little one & cherries!!

One of our little ducks doesn't seem to be growing as quickly as the others. We believe that it is a female since she doesn't have the yellow markings on her head (we assume the markings mean male...we could be wrong). Anyway, yesterday, I was headed to let the ducks out. I frequently count the babies (who aren't babies anymore!) to make sure no one got away. I counted 5. Where was the other? She was sitting in the box with the Mamma (who's sitting on eggs). I let the ducks out and all left, including the Mamma, except for our little one. She did end up coming out and wandering around. When it came time for us to leave the house, we chased the ducks back into their pen, but I only counted 5. The little one was sitting under the slide of the swing set (in the shade). I only figured out where because of the loud peeping. She is much easier to catch than the others.
One of her eyes looks kinda funny. Since we are certainly not duck experts, we are really not sure what to think of it. She certainly is slower and smaller. At the moment, we have her separated from the rest to take a break, but I don't think we'll leave it that way. Not sure about duckie depression, but I would guess that it happens and isn't healthy (like humans.).
Some websites suggest getting "toys" for the duckies to play with...um...haven't done that yet.

OH! OH! Who needs TV when you have live entertainment in the backyard?!! We ate fruit for dinner tonight and had a few cherries and apple wedges left over. Not enough to bother saving so I took them out to our "pond pals." I said, "I've got apples and cherries. If you want 'em, you gotta come and get 'em." And I knelt down outside of the pen and held out the fruit in my hand. Three of the young ducks (gotta stop calling them babies, cause they are too big to be babies!) were very interested. They ate those cherries right of the ends of my fingers. Actually, they mostly just grabbed them, dropped them, and the nice Mamma duck would eat them. The little guys ate quite a bit, but she was always there to catch what didn't make it "down the hatch."
Daffy, our drake...not to bright. Of course he wouldn't come near us (Bill got to share the joy), but we'd try to be nice and throw them toward him. He'd back away, scared. Then the babies, er...young ducks...would gobble them up. Sigh. When he did get one once, he was just too slow, dropped it and the others ate it up. Oh well. We tried to be nice to him...even though he's a meanie.

A note about feeding duckies from your hand...try to convince them to nibble the FOOD from your HAND, not nibble your FINGERS as FOOD!!! It doesn't HURT at the first little slip. Kinda feels funny. But the start chomping down harder the more times they end up nipping your finger instead of a cherry!!! Still not incredible painful, but certainly not pleasant.