My herd produced a lot of infertiles this year...and I can only speculate why. It may be that the males should be brought out of hibernation ahead of the females, a successful breeder I know says this greatly increased his herds fertility. Curiously, others don't hibernate at all yet have high fertility. Some of my animals are different phenotype, I wonder if this might mean incompatable breeders, perhaps different subspecies or from widley varied area/altitude? I have heard eggs above ground are usually infertile. My herd buries them, but I still have quite a few failing to hatch...and I lay awake at night wondering why? There's always next season! Multiple males improves fertility in many reptiles, and I have 3 cantankerous males. Good luck, Vic