Ask the Swan Specialist
Date: 2 August 2013
The cygnet is probably leucistic (lighter color) and the parents now think that it is a rival. This is what occurs once all cygnets turn white and are chased from the habitat to find a mate and eventually establish their own family and habitat. However, because the cygnet is only 2-3 months of age it may not survive due to predators and the inability to protect itself without its parents. There could also be something else wrong and the parents know. It is for these reasons that we would suggest rescuing the young bird if the parents create larger and longer distance and time from it or more signs of aggression.
There is a wildlife rehabilitation center in Manhatten that you may want to contact. Be careful about which facility you take it to as the state NY DEP promotes the non care and even killing of the Mute Swans because they deem them as non-native although there are individuals and entities which believe that they are native due to migration patterns. The Regal Swan