I am looking to build a new swan habitat for my 3 year old pair of black swans. I would like to build them really nice and safe home. We live in an area with bobcats, mountain lions, bears, raccoons, foxes and coyotes. Possibly other predators I have not been made aware of such as ferrets.

Can you recommend a good size for both the pen and the pond with the island in the center? Should I seed grass (what kind) or put in sod? Should I build a natural marsh land for natural filtration or go with a filtration system (if so type)?

I plan to have an automatic filling unit so it will always have adequate water.