Fun facts for anyone still reading:

Budgies can see into the UV spectrum, and glass blocks UV, so keeping birds indoors is a bit like putting a colour filter over all your windows would be for humans. So try to open the windows when the weather allows, using a mesh screen or something to stop your birds flying out.

Budgies' sex chromosomes are opposite from mammals. So the males have two of the same, XX, and females have XY, but I think they use V and W, too lazy to look it up.