My two ducks just started laying eggs last week. I have two drakes and two ducks(hen) but I have many size variations to the eggs. On duck lays green sharp oval eggs (the three in bottom left corner) and the other lays pink regular shaped but giant eggs but all 4 very in size. The egg that is buy it's self is a chicken egg for reference. shouldn't one ducks eggs be constant in size or should I expect this every time they lay eggs?