All,
Thank you for the serious replies. I am hoping that you all are right and they are simply hidden but I am not hopeful. The pond does not have snappers and we have not seen a water snake in quite a few years. It is possible a fox or raccoon got them. I will keep an eye out.
Here's a pic today of the ducklings that I have. They are sure growing up fast. However, the sad note is that there are only seven today. Sorry pic is too big I will have to resize it. Will come soon.