In 1987, 21 Swans were released in our area. We have discovered five pairs in our travels. Some are in potholes far from "Nowhere" ..some are in ponds very near the road. None of the Swans that we have viewed have identification neckbands..so I surmise that these are all wild swans versus released swans.
A Swan mainly eats submerged plants like water celery. I have noticed that one Swan..usually the largest..has a real dirty head. Now this is only my theory ...but it makes sense to me. Take the case of Sven..he is hard to photograph because he always has his head underwater. I am positive that Sophie tells him " Sven, you need to get me food cause I need to lay eggs soon. I will keep watch and you will rip plants out of the muck ALL day long for me to eat." Remember this is only my theory.. :)