If there is something wrong with the cygnet, the mother will abandon it. Nature will sacrifice one for the rest of the family/flock. If it was a runt, it could not keep up, again the mother is not going to wait on one because a predator could be led to the family.

The cygnet may not survive even with your care. It should be fed a mixture of poultry layer pellets and cracked corn. There are no guarantees that the mother will take the cygnet back from a separation more than a few hours. You can try, but very few swans will take a cygnet back after being separated. So, be ready for a rescue. If the cygnet is abandoned, you will need to find, a wildlife facility to give it a home. This is going to be a challenge in Virginia as your state and many others deem the Mute Swans as non native and invasive (both intentional misrepresentations by state and wildlife agencies) so that they can kill the Mute Swans, open up habitats to introduce the larger Trumpeter Swans for Trophy Waterfowl hunting purposes. So, in Virginia, some wildlife facilities, veterinarians and other state licensed entities will euthanize the Mute Swans and their cygnets so they do not lose their licenses. If you cannot find a wildlife facility, you might try a waterfowl sanctuary or a poultry farm that might have some pet geese or ducks to raise the young bird. Once raised in captivity at such a young age, the bird will need to be pinioned, between 1-3 weeks of age (rendered unable to fly. Then, it must remain in a very protective captive setting. Humans cannot teach it how to be a swan, recognize or escape from predators. As tough as it is, with your state DNR officials stance on Mute Swans, it may be better to let nature take its course if the mother abandons it unless you are prepared to raise and provide it a permanent home. The Regal Swan