Thanks for the additional info. You basically have a juvenile swan with hormones that have run amok. Usually, swans start to mate at 3, but because he was such a young bird at 2 when he began mating, he really had no idea what was occurring. Now, you have Dr. Jekyll and Mr. Hyde. If you separate him from the female, he may not accept her or the cygnets once he is released back onto the pond.

If the male swan is okay until the other swan or you enter his territory then this is the trigger to the misbehavior. Is there any way that you can keep the other swan from accessing the nesting habitat?

As far as his chasing you, this is normal, but if he is too defensive then it is not good. To stop him from coming out of the water and going after you, you will need to perform a time-out scenario for the swan. First, remember he is only protecting his family, so you do not want to hurt him, just discipline him without getting hurt yourself by the swinging wings.

You and another person need to approach the pond with a white sheet or blanket. As soon as he comes out of the water towards you, gently throw the blanket over him until he sits down and you can control his wings. Gently grab his neck while controlling the wings and keep him near you for approximately 5 minutes speaking to him softly and gently petting him. Then, release him. If he comes back towards you, repeat the process, keep doing this until he gets the idea that chasing the keeper is not acceptable. The idea of the sheet or blanket is that you are the bigger (white) swan and you own the pond, not him. Keep the sheet with you for several days waving the sheet at him if he begins to come out of the water. Repeat the process if he comes out of the water. He is going to get the picture real quick and will not leave the water for you.

More than likely, this showing of who owns the pond will keep him from you and by keeping the other swan from the pond, things should settle down. Usually, the hormones return to normal in about 2 weeks and then you will have Mr. Docile again until next nesting season. Please let us know who this situation progresses. The Regal Swan