There's a swan nest in our back yard. The swans laid 7 eggs. 5 Eggs hatched within 2 days. 1 egg disappeared. Do parents discard bad eggs? And really my questions is, its been 4 days since the last egg hatched and there is one egg left in the nest. The female has come back to sit on the egg at night so far every night but leaves with the babies during the day.

Might that egg still hatch??? I think that I keep seeing the egg stir a little bit... am I seeing things? or might it be moving slightly?