I have 4 mallards 3 females & 1 male, their 22 weeks old, 1 of my females starting laying eggs last week, I've gotten 1 egg a day from her my other 2 females haven't started laying yet, is this normal??? They all stay together when they are outside during the day & at night they are in their pen. I'm a very protective mom I know where their at, at all times so I would assume I would see eggs when I walk around the yard when their outside. I feed them DuMour grower/finisher from Tractor Supply. Any ideas, are my 2 females just late bloomers?????