Another broken egg

The mystery deepened today when Topsie found another broken egg.  This too was a duck egg similar to the one we uncovered the previous day.  It was located closer to the pond, and it too had been cracked open and emptied of its contents. We noticed similarities in both cases.  For one, both eggs appear to have been broken in a similar fashion with an opening or hole having been made in the top of each egg.  The other thing we noticed is that around both eggs shallow holes had been dug in the earth.  Despite these clues, we have yet to solve this mystery.

This too was a duck egg