baby 4 weeks old

Hello, my name is Estela, my cockatiels and I are new parents to two babies they are about 4 weeks, but he is totally bold except for the top part, I dont see any feathers coming from the top of its head, and he does not walk much. Do you think the parents are plucking? is it bad nutrition...

I was given a baby that is supposedly 8 weeks but I bought a scale today and she only weighs 75 grams they were telling me to feed her twice a day but she is crying all the time I feel like an idiot she is such a whiner, she cries all day and whimpers unless I cover he in her bin and as soon she...