If they are a darker color, they are all probably royal mutes as opposed to polish mute cygnets which are white in color. This genetic coloring does not pose a danger to any of the swans and even though the cygnets may appear royal in color, they still will have the polish mute gene (leucistic coloring) and can produce either coloring once they produce cygnets.

As long as you can capture the cygnets and get them to the veterinarian and return them in a reasonable time (2-3 hours), the parents should take them back with no problem. If you keep them from the parents for extended periods of time, then the parents can reject them. This is why it is important that you make an appointment with the veterinarian beforehand so that he/she knows that the cygnets are on the way and no delay occurs. The Regal Swan