What do you mean by natural barriers? If you are speaking about bushes, trees, etc., yes swans need these items around the pond for shade and shelter. They will crawl under bushes for shade, to get away from people and even use the bushes for nesting. However, if the bushes are readily available to other animals, specifically, predators, then they are not a good thing because it will be too late for the swans to see a predator coming and they may not be able to escape thick brush.

As far as man-made shelters, swans typically sit for extended time periods in the straight sun and do not like items above their heads such as housing. If you can provide the swans with ample aquatic vegetation such as pickeral weed, lemon grass, etc., these items will not only provide shelter but will also provide a nutrient rich vegetative food source for the swans. The Regal Swan