Why are my budgies dying

by David
(Adelaide, AU)

I have 4 budgies die on my the first pair, I had for two week which I purchased from a pet store, one night the was a lighting storm and a large clap above my home and the next morning the were die so I naturally thought the thunder shocked them to death, the cage is not a normal size the cage measure 3mx2m and has a small bush growing inside the cage.

On of the budgie I had one week early to the second one. I replaced the tow that died because of my son with another two were purchased from a differnt pet shop and lived for 2 weeks these birds were both males and in the last two day I have interjuice a female into the cage and I tonight have found the two males dead, one in the shelter box and the other was on the ground, the previous pair were the same one in the box and the other on the ground. So far the female is still alive, this time I clean out the shelter box and put grass for comfort, think the might be something in the box that could be kill them.
I really would like your option
thank you