First, the smaller one may not be a female. It may be a male and the male parent swan is seeing a rival and wants the younger bird removed from the habitat. This same behavior will probably occur once mating season begins and the last remaining cygnet will be told to leave the habitat and find another pond and a mate. This may have been what occurred in the beginning. The younger bird may not have been able to fly as well as the others, the parents wanted to migrate and now everyone is stuck in your pond instead of migrating.

Second, there may have been something wrong with the younger bird. If it cannot keep up, is sick or injured, the parents will either try to banish it so that predators cannot follow it to the rest of the family. The male swan may also try to kill it to put it out of its misery if there is something wrong with it.

Third, if all swans do not leave the area before the pond completely freezes, you will need to effect another immediate emergency rescue. The swans can drown or freeze to death if they get caught between the ice and cannot get out of the water. They will not have any aquatic vegetation for a food source and can starve. They will need to be fed supplementally. However, you have to be careful not to throw the food near banks or areas where the swans can be attacked by predators. Predators such as foxes, bobcat, wolves, coyotes will go onto the ice and attack the birds, especially during winter as their food sources are also being depleted. A trapped bird is an easy target.

If the swans do not fly away, the best thing to do is to effect a capture, take them somewhere they can spend the winter until the pond warms over and they can spend the night in the pond free from predators and the possibility of freezing. Once springtime appears, the swans will probably fly to another area or at least have a fighting chance with a warmer pond. The Regal Swan