More than likely the predator was not an owl. It was either a fox, coyote or bobcat. We had the same thing happen to a pair of swans at a facility that we act as consultants.

It is very difficult to protect swans in an environment such as yours. Once predators find out that the swans are easy prey, you will have a hard time protecting them short of penning them the rest of their lives. Unfortunately for you, our recommendation would be to find the female a nice home so she can be repaired with another male and live her life out in a safe habitat. The only other alternative is to fence your entire pond (set from the pond about 100 feet with electric wire on the top and bottom of the fence (ensuring that the swans cannot contact the fencing). Even then, a large bobcat or other cat species such as a panther could easily spring over the fencing. Good luck. Please let us know how this situation is resolved. The Regal Swan