how old does a duckling have to be?????

Fully feathered is my general rule.

 

And I would add - please monitor closely especially at first. Drakes can sometimes be too, too aggressive, and I feel it is our job to protect every member of the flock.

 

Our ducklings come off the nest and we have several drakes with our hens but they have not harmed the ducklings. They don't bother ducklings raised inside when we put them out either. The drakes will hang out and watch over the hens on nests but they will try to get some action when she comes off the nest to eat and drink. I have not seen a drake chase after a duck with her ducklings, though.

I have read that people with different duck breeds can have some overly aggressive drakes that have attacked ducklings when they hatch. If you have an aggressive drake you will need to protect your ducklings. I have not had this issue with all my years of raising ducks but it does happen.