We're not really sure what a tail wag in a swan means. Some researchers think that it is stress while others think that it is similar to a dog's wagging tail in that the swan is showing some sort of greeting. If he is snorting and wagging the tail, we have seen this behavior and it appears to be a form of a greeting.

If you can feed him lettuce along with the bread as well as cracked corn and layer pellets, he will have an adequate supplemental diet in addition to what he eats on his own. The Regal Swan