I have 23 duckies, only 7 are old enough to lay eggs... Out of my 7 older ones, 2 are males and the rest female. And over winter they all started laying eggs. They all pushed their eggs into piles but only one of my females would lay on her eggs. after about four days she stopped. Then when spring came they all stopped laying again, and then started again about a month ago, yet again there are a billion eggs some in piles some not and yet again no one is sitting on them this time. Is there anything that would cause them not to try and hatch them?