We just have the 2, Adrian and Rocky, that we got in early December 2021. I was a bit concerned when someone had posted (elsewhere) that Rocky looked to be an English, and was purported to be issues with health as The are more bred for looks. But then an English Budgie in this thread lived to be 16,
@JLcribber which sounds better.
I think proper eating and enough sleep will play an important role in lifespan. Our Toy Fox Terriers are senior dogs and Little Bear is 15 and still going strong. MUCH love as all 4 sleep in bed with us, BUT they all do take a lot of naps during the day. Good diet, but not TOO much of it, IE too overweight, or too much fat taxing o the liver, along with decent amounts of Vitamin A, as well as minor nutrients and calcium.
One thing that I think gets overlooked is "US" our mouth and saliva has gram negative bacteria in it that is toxic to the point of being deadly to the parrots. I read that recently. Kissing them, sharing food "our of our mouth" I feel can be a possible gateway for a bacterial infection that they struggle to fend off. Now here is the thing I did read....that the bacteria is pretty much made safe once it dries, but it is the wet saliva, or mucous (nose) that poses the most threat. So a sneeze on your shirt, and it's dry, will not likely have any effect on a Budgie. Sneezing direclty on them probably will.
Genetics, weight, exercise, sleep, balance nutrition, and most of all love and affection will, I believe, create a scenario for a longer happier life. You do the best you can, and learn all you can, .... what more can we ask for?