Hi,
I’m very sorry for your losses. The deaths may or may not be related. There are many reasons a bird might die. It could seem sudden, but the quaker may have been sick and you just didn’t realize it. They are good at hiding signs of illness.
As for the cockatiels, it is possible they were sick when you bought them. It is stressful for a bird to go to a new home. Sometimes this stress can cause an underlying illness to take over and the bird can die. Again, they may have been hiding signs of illness before they died.
That being said, if these were sudden deaths, the cause is usually something airborne. Birds have a complicated respiratory system and just about anything with a strong fragrance or fumes can kill a bird. Some common household hazards are non-stick cookware with Teflon, cleaning products, scented candles, plug in air fresheners or room sprays, smoke from burned food, & again anything with a strong smell. Another concern would be carbon monoxide. Birds would die at lower levels than what affects people, but it would still not be good for people if you have a carbon monoxide problem. The best thing to do is have your home tested for carbon monoxide and then try to think about anything that could have poisoned the birds. It is enough of a concern that I wouldn’t bring another bird into the home until you are absolutely sure there isn’t something airborne that is causing these deaths.
Take care,
Brenda