Usually, swans mate for life, however, there are some exceptions. We have had heard from noted swan specialists that male swans will sometimes nest with two females at the same time, but will spend most of the time with their preferred mate. This second nesting may be aberrant behavior or may mean that one or both of the original swan mates are infertile and the second mate insures the perpetuation of the species/flock/genetic line. Usually, successful production of cygnets assists in the mates staying together.

In any case, it is likely that one of the female swans will be responsible for caring for the cygnets on her own. This is not to mean that the male may not visit the second nest upon hatching, but in most cases, the female is the one that is primary caregiver of the cygnets while the male affords protection to the nesting territory. The Regal Swan