cresteds actually aren't temperature sex dependent. mine incubate at 76-78 degrees (78 is about as high as you want it to get) and i get a good mix--last season i actually came out with more females than males. last year i bought 2 hatchlings from someone who incubated in the low 60s and the eggs hatched at day 120. both turned out to be males. i knew it didn't really mean anything when i got them but i figured i'd take the chance.