As you can see there's lots of differing opinions out there. All I know is what I've been doing for quite a few years has worked well for me. I've raised a lot of ducklings to a healthy adulthood. The only duckling I've ever lost is one that wedged itself in between a concrete block and the side of the pen they were in. I don't hatch my call ducklings......I let the hens set and then when they hatch I take them away.