Where are the eggs?

On St Patrick's Day the local trio of Muscovy ducks deposited 11 eggs in a nest right next to one of my down spouts. Very cool, I thought, since I love to see the babies when they hatch.
Over the next several days the total swelled to 30! At first the two Momma ducks seemed to be paying very little attention to them & were hardly ever sitting on them, so I was wondering if I was going to end up with a pile of smelly eggs after a while.
Then one morning about a week later I came out and saw two of the eggs lying several feet away from the nest...one demolished and empty of contents, the other was cracked open and losing the filling on the ground. After that, the Momma's started sitting on the rest of the remaining eggs most of the time, although they would still get off, usually taking turns while one wandered off to the pond for a while.

In the mean time, my yard has turned into local wildlife central...spotting a wild rabbit a couple of times, and a snake skin of a decent size, followed the next day by seeing the black snake it probably came from, and he looked about 3 feet long, but not very thick. In other words I don't think he was large enough to be stealing rather large duck eggs! I never did see what might have gotten the first 2 eggs and after a few days even the shells had disappeared.

Most of the time when I go out to give some bread to the sitting Momma's I can still see a lot of eggs on the nest, but I noticed yesterday while they were standing a few feet from the nest, taking advantage of the shade, that one of the eggs in the nest was damaged, so I took a closer look. Now there are only 20 eggs in the nest! No sign of any shells anywhere around the yard, so it's a mystery to me where the other 8 went! Some folks around here have suggested that I harvest the eggs & eat them, but I'd rather not! Hope that isn't what is happening to them.

I read on line that this breed of duck has a 35 day gestation period, so I guess I'll find out later this month how many little ducklings have survived for me to be their honorary Granny. Then I just have to hope that the grouchy couple across the pond doesn't start killing them off like they did a couple of other batches that have hatched in the last couple of years!