Is his mate still around?How can you be sure this is the same bird? Both of these questions could possibly answer why he is not making sounds. Not being mating season could be another reason.

Not having a substantial portion of the webbing is not necessarily a detrimental injury. We have seen this type of injury caused by a soft shelled turtle and the swan has had a great life and is still alive 13 years later. As long as the swan can still enter and exit water it should be just fine. If you still have concerns, it would not hurt to get the swan to an experienced waterfowl veterinarian for a checkup with blood tests to ensure that there is no throat or neck injury or infection. The Regal Swan