Mother swan knows best. If she has rolled the eggs out, then they are bad. Bad eggs will rot in the nest and that is a messy explosion she cannot afford. Her attention is totally on the eggs that will be viable.

Once the eggs are rolled out of the nest, they will not survive as they will be too cold at night and too warm in the day. The mother's weight and body heat regulate the temperature of the egg. Without her sitting directly on the egg, the egg will not survive. The Regal Swan