A Bad Egg?

On my trip around a lake in Lakeland on Easter (while hunting ducks), I saw many of the swans had built large nests and were sitting on them already. But I stumbled across one nest that had no swan on or even near it. But at the center of the nest was a single, large, slightly bluish egg the size of your fist. I don't know if mommy and daddy swan had just wandered off for a moment or if they'd given up on the idea of parenthood. I don't know how long an egg like this can survive without the warmth of the parent to keep it alive. The temperature outside was pretty warm, but somehow I think there's more to it than just ambient temperature. But anyway, here's a picture of a swan egg. You aren't likely to see that on too many blogs!