What are the symptoms? How many swans do you have and are these the only two that have been affected? Could the swans be affected by the recent terrible snowstorm which may be affecting their food source, rendering them sick, etc.? Was a necropsy conducted on the black swan?

If you can capture the male and any other swans, you should get him and the other swans to a veterinarian to see what might be causing the symptoms and if the possible cause can be treated and prevented in the other swans. If you can get a necropsy conducted, a better idea of what is occurring can be rendered.

Without knowing any specific symptoms, we really are at a disadvantage of advising you of what needs to be done other than a capture and visit to the veterinarian. Good luck. Please let us know how this situation turns out. The Regal Swan