Motherly Love?

Maybe one of my fellow blippers can explain what is going on here.
Of the original seven signets and both parents, there are now only five signets and the mother left. As you can see four of the signets are healthy and virtually independent. However the fifth one is much smaller and while I was walking round the pond, it was being chased round and round the central island by the mother swan. It was quite uncomfortable to watch and the small signet seemed to be in distress. Is this normal behaviour? Is the mother just trying to force the runt of the group to move on?