[dancelady]

I meant to turn off the heat register under the cage -- not the whole house! Just flick the register thing closed and that will help. It won't make much of a difference to the other birds -- they can live in a slightly colder temp.

I don't believe that there is anything that could make two birds die at once, other than heat. If there was, it would affect the other birds.

I would just turn off that register, maybe move the cage a bit, and don't put anyone else in that lower cage. I don't think a necropsy will tell anything other than heat exhaustion. You also have to consider moving the cage upward on a stand or something to raise it -- if you want to use that lower cage portion. I am an engineer so I can attest to the problem with heat. Also the cleaner you used and the area where the cage was broken didn't do it, because the metal would have resulted in a severe poisoning trauma which they didn't have.