Incubation usually lasts between 30-45 days from the date of the last egg being laid. Female swans will usually not sit on eggs that are infertile or have little chance of hatching. So, she knows something that we don't know. Give it a couple more weeks (about 2). If she still has not moved from the nest, you might want to check to see if there are indeed eggs or cygnets and if not, you might want to remove the eggs so that she will leave the nest.

As far as snapping turtles, there isn't much that you can do about this problem now that the nest is in the middle of the lake. If cygnets hatch and you can collect them and the parents, you will need to place them in a penned area (half in the water and half out of the water with a feeder in the pen). Place poultry chicken fencing on the bottom of the pen and secure the poultry fencing around the perimeter of the pen. This will keep the turtles from digging under the penned area and getting to the cygnets. If you choose to pen the family, you must also find a safe secure area for the pen so that other predators, i.e., foxes, coyotes, bobcats, etc., cannot dig or crawl over into the fencing and have an instant easy meal. The Regal Swan