Have 6 eggs in the bator right now, 5 of which are in lock down. Before locking down I checked all the eggs and they are all looking great in all the right departments but one of them has an itty bitty air sac. The egg is in lock down, day 25, and the air sac looks comparable to something you would see in week 2. I never paid much mind because the duckling was developing just fine from the looks of things but now I'm worried. This is my first run with eggs that my own ducks laid, mama (Bleeker) is a Blue Swedish and the dad is a Splash/Silver Swedish (Juno). Needless to that their name stuck even though there was some sex confusion when their names were administered. It is also her first big run with laying eggs. She wasn't much for brooding, but she lays like a mother, lol and our drake seems to be more than viable. The air sac issue, could it be related to the age of the parents? I can't recall their ages but I do know they were bought as day olds from Privett hatchery stock (Splash drake) and Dunlap Hatchery (Blue hen/duck) back in mid March.