Mother duck singling out one duckling.

[Chloevr]

My Runner duck has 6 beautiful babies.
She keeps picking on one baby. It’s not hurt or weak. She does not attack it with force but keeps pecking it.

I did catch the little baby and he sees very strong and not hurt.

What could cause this?
Daddy is doing a fantastic job and walks with the last duckling hatched. It’s a little slow still and he stay by its side.

 

[Miss Lydia]

I don't know what would be the cause since it seems to be healthy and strong.[Hard to know what goes on in the mind of a mama duck] About all you can do is keep an eye on how mama is interacting with it and if things do start to get worse take it and maybe another for company and then try later to integrate them back into the whole flock when they are older and larger.
That is sweet dad is helping out.

 

[JeremyCarlsten]

I keep about two dozen ducks and I've seen this happen a few times. Usually the mom is picking on the one that either hatched last or is just slightly "different" to her — could be something we can't even see, like a smell difference if it took longer to hatch or was in a different spot in the nest.

As long as the pecking is just light corrections and not drawing blood or preventing the duckling from eating/drinking, I'd keep a close eye on it but not intervene yet. In my experience, most duck moms settle down about it within a week or so once all the babies are moving at the same speed and smelling like the group.

If it gets worse, blood or not letting it eat/drink then I'd intervene