I think your female is a normal mauve budgie and your male is a normal light green budgie. They are both american budgies. Your female's cere change colours depending on breeding condition, it goes from white and light bluish tinge to a tan till it reaches a crusty dark brown colour which will indicate she is ready to breed.
I don't think there is something wrong, it's normal for them to lose weight during breeding and the females also pull some of their feathers for nesting and keeping the eggs warm. As long as the parents are having a good diet adequate for breeding, lots of good seeds, veggies, calcium, eggfood, then things should be fine.
I currently have a breeding pair with 3 chicks and both parents lost a bit of weight, especially my male, but in his case it was good for him because he was on the plus size and now he is more fit and not too skinny.
My female has been displaying the white cere for over a week now and there is nothing wrong with that, she keeps feeding her young as usual.
Dad is a Normal Yellowface mutant 2 Skyblue and mom is a Normal Mauve. All their chicks should be Cobalts anyway.
The mother looks stressed, and perhaps losing feathers due to a moult?
Changing of her cere colour back to blue means she has gone out of breeding condition, as in her body is no longer supporting her hormonally to go through with the process of breeding smoothly.
It will turn brown again when she will want to start laying eggs.
Details about my budgie?
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