One of my budgies, Coconut, has been raising a pair of chicks for the past few weeks. Lately I've been finding the chicks on the aviary floor, I guess it's almost time for them to leave the box and become independent, but they still can't fly very well so I put them back inside the box. However, this morning when I checked the aviary, one chick (pictured below) was on the aviary floor, and the other was dead inside the box.
The surviving chick doesn't look too good because Coconut's chicks seem to have less down feathers than usual, and a few weeks ago, the chicks were attacked and had several feathers pulled out. Judging from the condition the dead chick was in, my guess is that Coconut killed the chick. It is possible that another budgie could have done it, but Coconut is very protective of her box and usually chases away any females that go near her box.
Coconut has raised many clutches of chicks, but so far none have reached adulthood because Coconut seems to kill her own chicks just as they are about ready to leave the box. In fact, a few weeks ago, Coconut killed Crystal, another female budgie, who entered her box. Perhaps when the chicks grow up and develop their adult feathers, Coconut sees them as intruders and attacks them. Or maybe Coconut gets sick of the chicks constantly begging for food, I don't know.
I don't really know what to do, when the surviving chick ends up on the aviary floor, I put it back in the box since it doesn't know how to feed itself yet and it can get cold on the floor, but I worry that Coconut might kill it if I put it back in the box. I hope the chick will be okay >.<