We have lived on Little Wolf Lake in Jackson Count Michigan for 7 years. Each year the same pair (i think it is the same pair) have made a nest and produced 5 to 7 cygnets. The old cobb fiercly protects his territory and drives off all other swan invaders. This year has been differt. We have seen up to 17 adult birds gather on the lake. The Cobb tried in vain to move them out of the lake and it appears that there will be more than one pair this year. The lake level is at a 40 year high according to our life long at the lake neighbor. Is there some behavior that would account for this change?