The eggs should remain in the nest until at least 1 week after the other eggs have hatched. The mother swan will either abandon the eggs or pitch them from the nest if they are duds. The worst thing that could be done is disturb them in the event that a new hatchling occurs. This would mean that the mother would not take the young cygnet back and you would have to raise the birds until adulthood which is not a good thing for either you or the bird. The raising of a cygnet until adulthood is extremely difficult and time consuming. The Regal Swan