More than likely, the parents are starting to chase the cygnets from the area to prepare for the migration and upcoming nesting season. If you have a local swan sanctuary in your area, you might check to see if they may have reported capturing sick or injured cygnets in your area. You might also check with the RSPCA to see if they may have any reports of cygnets being rescued.

If not, then more than likely they are beginning to fly. In any case, by alerting the RSPCA or the swan sanctuary/wildlife facility, they may come out and check on the family to insure that the remaining family members are not sick or injured. The Regal Swan