Is this normal poop for a duckling?

[Duck_Mama]

I'm a first time duck owner and Im worried they are not getting proper nutrition or something might be wrong with them. Two of my pekins are balding which has been worrying me, I don't know If it's normal. One has diarrhea and the other has poop that looks like this. I feed them duck feed and dried worms from tractor supply. They were eating lettuce and kale, but I stopped feeding them the greens over the past 3-4 days. I love these little guys and I want to make sure they are healthy.