The male Black Swan is ready to mate this year so he is acting normally. It usually takes 2-3 years before swans mature and now your child has become an adult. Keep the species separated, especially during mating and nesting season. The male swans can easily injure if not kill each other and the cygnets. Typically, the Australian Black Swans are more defensive than other species. See if the behavior calms down. You can also minimize his aggressiveness by becoming the bigger swan. If he charges you, stand your ground. Do Not back down. Gently grab him (you may need someone to help you). Be careful so you nor the swan gets hurt. After capturing him, tell him no and snugly hold him. Place him in time out for approximately 20-30 minutes in a safe garage, barn or bathroom. You want him safe from a predator or from hurting himself. Then, place him back in the pond. It will only take 2-3 timeouts before he avoids you like the plague and decides to stop engaging you. Please let us know how this situation progresses. The Regal Swan