More than likely, the mother swan was trying to protect the cygnets and went toward the threat and left the cygnets in an area that they could readily escape. Swans teach their cygnets to dive when in trouble and meet in another area of the pond where mom can catch up and lose the threat. The mother was actually protecting her cygnets and trying to remove the threat, even if it meant leaving the cygnets and drawing the threat away from the area, i.e. separating the family. The Regal Swan