I have only seen two of mine die so far. Both within the last week or so:
Houdini - Winter White Male - approx. 2.5 years old - Old age?
Lemmiwinks - Winter White Male - approx. 2.5 years old - Died from tumors/old age
I think they were both the same litter. A third one,
Spazz, was in the same litter too. He is still very healthy and still going strong (unusually active considering his age actually). I also have a fourth Winter White,
Marilyn, a female I got from a nearby store. She was tagged as a Winter White, but she might be a Campbells hybrid. She looks kinda haggard, but otherwise seems fine. Pretty active. She is around the same age as the other three.
I don't know for sure what killed Houdini. I know for sure Lemmiwinks had tumors though.