So glad to find this site. We are seeing a similar situation and it is breaking our hearts. The mom has been on this nest since March 31. At that time there were at least three eggs. A month later there was one egg and now we have seen no eggs at all. The nest is becoming smaller and smaller each day. It was a work of art that both swans could fit on a month ago or so. Her mate stays close by fishing usually. She rarely leaves the nest. She is panting a lot. We have written to a wildlife rehab contact in the area and they tell us to let nature take its course. Thank you for any advice.