Without a necropsy (an autopsy for animals), we could only theorize how the young cygnet died. There are several possibilities:

1. The parent killed the bird by accidently stepping on it or trying to remove it from climbing on the parent's back. Some mother swans, and especially male swans do not allow the cygnets on their back although the riding on the back is a trademark attribute of swans and some ducks.

2. Herons could kill the cygnet, but usually some type of trauma does occur and the herons will eat the young.

3. Another type of predator in the area such as turtles, hawks, etc. Again, some trauma would be noted.

4. Egg sac peritonitis in which the egg sac does not fully dissolve and peritonitis of the abdominal cavity occurs. Usually, there is no sign of this occurring, very spontaneous and you would only know if you picked-up the cygnet and could feel that it was running a very high temperature.

5. Poisoning by eating something it should not have eaten is a good possibility. What insecticide, pesticide or fungicide or other chemicals are used on the ornamental corn? Is there mold on the corn and how old was it? Any of these could cause the swan to get sick or die.

6. Accidental drowning. If the young cannot get out of the water to try and stay dry, or it has been raining, or temperatures drop at night and because of lack of feathers, the bird can catch a cold and get so sick that it gets pneumonia and dies.

So, any number of events could have caused the cygnet's death. The Regal Swan