Runner Duckling Q

[RunnersinMD]

My ducklings hatched Sunday and Monday, so one in two days ago. One of the ducklings had a really hard time getting out of his shell and is clearly not as strong as everybody else. I was cleaning out their brooder and lifted him out and realized he had a red underbelly , is this normal? I honestly didn’t think he was going to make it through the night, and he seems significantly better than yesterday… But he still definitely is behind the others.