Originally Posted by Suncoast Herpetological

Heather as your colony matures and ages, it is not all that uncommon. The method that most breeders (myself included) use to brumate is a gradual drop in temperature down to a specific target temp and then they maintain that temp for a fixed period. At the end of brumation you gradually raise the temp back to normal. This really does not mimic natural brumation in that in the wild, there are temp spikes all during the brumation season. Usually the reason for losing an animal is less than optimal body weight or simple age.

I currently brumate about 400 animals and I usually lose one or two of the old ones to brumation each season. I firmly believe that it constitutes a natural death that probably would have occurred in the wild as well from the stress of brumation.