i am waiting on birds going down on 2nd round.then i take 1 of the eggs out and replace with plastic and end up with single reared yb.s. reason is before yb,s are ready to leave nest training starts and if i loose any in training i can swap yb,s about. it worked for me before and think it will work again . and all yb,s will have to compleate yb program things you do on your first year back