How to relax your baby ducks and keep them happy?

If you have a few of them. They will group up together and comfort one another. Put them is a enclosed container such as a tall box with no top. Giving them plenty of room to move. Cover the top with a breathable fabric to keep the light out. Just as people cover their bird cages at night. Doing this many times throughout the day will allow them to calm down and relax and within a few days they will become acustomed to the noise, smells etc. and they should be easier to deal with.
Hope that helps.
+5

They like heat such as a light, make sure it's not to hot. Plenty of water to play in and drink. And always keep them together. A cage that no other animals can get in.

Besides a large enough bowl of FRESH water DAILY (that they cannot drown in,food,clean dry area,A MIRROW is the key!!If u only have 2 ducks or so they will become attached to you and will cry when u leave the room.A full length mirrow on floor horazontally will keep them content.NOW I CAN SLEEP!!Hope this helps someone!

No mommy duck? Find some video or audio online and play mommy duck sounds to them? (I really have no idea but this could work.)

The more sheltered and quite their surroundings, the better. If they are pets, they should be kept away from other animals until they are fully able to seek shelter on their own. It's not much different from baby kittens, except you probably want to keep human contact to a minimum. Is their Mom around? If not, consult your veterinarian.

Feed them duck food