We Watched An Adult Duck Kill A Baby Duck...why Did She/he Do That?

Perhaps it was not her duckling or the duckling was ill. Sometimes they kill the smallest one to give a chance to the bigger ones.

I also think that the baby may have been sick. I think that a lot of animals in nature kill babies if they are sick or weak.

All barnyard animal's are capable of this. One of my oldest best cochin hen's killed a baby polish chick that got thru behind some wire away from it's mother.Turkeys and geese are the worst for killing baby duck's, chicks etc.It's sad but it happen's.