May I suggest this. She got the clear tarps up just before the storm hit. Neither Nature, the cocks nor hens know she was going to put the tarps up so they would not have had time to affect fertility, IMHO s0 the premise put forth by TheDragonLady seems to carry.You got your plastic up just before the snow storms hit, right? You don't think the fertile eggs are because of the warmer temps inside their "greenhouses?" Still, not challenging, just thinking out loud.