During mating/nesting season, swans have an increase in sex hormones. This is especially true of the males. In your case, the male may be taken off the pond until the testosterone levels normalize. Taking the male off the pond until hormones level is a way to protect him from getting hurt during fights with other swans or waterfowl. It also keeps him from chasing residents and possibly getting hurt from a human that doesn't want to be chased. In any case, the female will do just fine raising the cygnets on her own or until the male is returned. The Regal Swan