Any non-abrasive surface such as grass, straw, sand, soil, etc. would help in the prevention of bumblefoot. Avoid hard and abrasive substrates such as gravel, concrete, asphalt, etc.

If you are planning on having a water feature such as a man-made river, etc., straw and other such material will affect your filtration system by falling into the water and clogging your filters. It will be bad enough with the number of swan feathers in such a man-made water feature.

Therefore, if you can use fine sand or soil, the swans will have a soft surface to walk upon and the filtration system should be able to handle the sand/soil. The Regal Swan