Last summer Mack and I gave a home to two ducks that were rescued as tiny babies (right after Easter) by an employee's sister.  The ducks had apparently been turned out when they were no longer cute little duckings and had been mauled by something.  The duck that turned out to be the male, now named Chester, was in pretty bad shape with a badly damaged leg.  When they became too large to keep in town, we gave them a new home.  We tried turning them loose in our pond, but they simply couldn't cope with the tough life and competition so we put them in a special pen--it has a grassy run with 36 inch poultry wire and an enclosed area about 16' by 4'.  We shut them in the enclosed portion of the pen every night to protect them from predators. 
About seven weeks ago the female, Gemma, started sitting on a nest of beautiful eggs.  After a month one little yellow ducking emerged.  It looked like a yellow cotton ball with eyes, a beak, and two little legs.  We called him Squeak after the squeaks in the song about Rubber Ducky from Sesame Street.  Squeak has been growing fast and incredibly full of energy.  He also knows no fear.  When I go in the pen to feed him and put fresh water in his little pool, he is so excited he comes running full tilt at me--sometimes even running into my legs.  Extra care is essential to keep from stepping on him.
This morning when I went out to the pen, Squeak didn't come running; he wasn't even visible.  I called him and was looking franitcally into his pen when he finally emerged.  He was all bloody and his little eyes were puffy and half closed.  If he had been a teenage boy, I would have said he had gotten drunk and in a very bad fight--but Squeak is a duck and was locked in a pen we thought impregnable with his mother and father.  I couldn't believe it so I started examining the enclosed portion of the pen closely looking for a hole or space a raccoon or mink could have squeezed through.  Nothing!  But, while I was looking Chester grabbed Squeak by the neck and started bashing little Squeak's neck and head onto the ground all the while trying to stomp him.  I couldn't believe it.  What could Squeak have done?  Is he a little male and is Chester trying to get rid of competition?  Is Squeak a female and was Chester trying to breed her?  It just didn't make sense.  Our roosters and ganders are such good fathers.  They don't even care if the babies are theirs.  If it is a baby they take care of it.  What is wrong with Chester?  Mack rushed in and got Chester out of the big pen.  He is now totally locked out and on his own.  When we left, Mommy duck was resting beside Squeak trying to protect and encourage him.  She was even plucking down off her belly and covering the bloody spots.  She had him arranged so he could sip water without getting up.  He seemed to be getting the best of care.  We hope he will be fine and that he hasn't suffered any permanent damage.  And as for Chester, I don't know!!!!
The picture below is of Squeak (before the attack) and his mommy.