What do you use to brood your ducklings in? The first 2 or 3 weeks, I use a large cardboard box. I do have a large wire pen Im thinking of putting them in when they are 3 weeks old. It has 1/4" hardwire cloth over all the sides. Here are my new ducklings that hatched yesterday night. 9 out of 12 hatched. What was strange was that out of my mixed color call ducks, I got gray and white ducklings.