Yes, swans will discard bad eggs and will stop sitting once they know that the eggs are not viable. As long as she is sitting on the egg, it could hatch. However, if she leaves the nest for any significant period of time during the day, then the chances decrease because the egg will lose warmth which is critical in hatching and the survival of the hatchling.

Additionally, if the egg hatches without the mother sitting on the egg, she may abandon the nest and the cygnet because it can't keep up with the older brood and/or she will leave to take care of the older cygnets and not return to the nest. If the egg hatches and the mother does not take care of the cygnet, it will die without intervention. Meaning, if you do not want nature to take its course and you decide to intervene, you will need to get the cygnet to a wildlife rehabilitation center or raise the young bird yourself.

However, if you live in Michigan, Illinois, Indiana, and other states that view the Mute Swans as an invasive species (which they are not), your state wildlife agency will have the young bird killed anyway. Wildlife agencies, especially Minnesota, Wisconsin, and Michigan are doing everything they can to kill all Mute Swans, their cygnets and destroy all nests and eggs.

The reasoning is that if the wildlife agencies depict the Mute Swans as being non-native, invasive, aggressive and all of the other bad publicity and misrepresentations, taxpayers will buy into their killing plan. Actually, the Mute Swans are an indicator species alerting to problems in the environment and their benefit is supported by international swan and wetland habitat specialists as well as current research.

However, wildlife agencies keep killing the Mute Swans because they want to remove them from wetland habitats and introduce the larger Trumpeter Swans for Trophy Waterfowl hunting purposes. So, it is all about getting more money for larger waterfowl from hunters. You can contact your local state senator and assemblyperson, but we doubt that it will do any good as this killing is and has been continuing with no scientific research. You can follow our fight on the Regal Swan Foundation's Facebook page. The Regal Swan