If the aggressive behavior only exists when you are around, this may mean that they somehow feel threatened by you and they are associating you with the cygnet. If they see you pick it up, etc., they may be trying to put the cygnet out of its misery of being taken by a predator (you). Can you release the cygnet away from the group so that it enters the water with you out of sight, yet you can still quickly intervene if necessary? If so, observe the cygnet and see if the birds better assimilate without you.

Also, the larger pen will work if the cygnet needs to be separated.

Please let us know how this situation progresses.The Regal Swan
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