Yes, Mathew is correct regarding the brumation, versus the hibernation period. However, this tends to be more of an individual tegu difference. The gradients temps from Arg. to Columbia vary by approx. 5-7 degrees at both ends of the spectrum. Golds do cycle as other tegus do and perhaps those not brumated/cycled are not acclimated well-enough. As any tegu though babies should never be acclimated. I wait until they are 1 yr of age to deter any ill-effects physically.
South American regions, for the most part, are reversed climatically from our regions. Being their winters are our summers, etc. Most gold tegus are farmed raised from southern Arg., Paraguay, and northern columbian "imports" though the later are not too frequent, if any any longer.
This also holds true for paraguyan Reds and B&W's. When people first obtained these species they are not use to, or knowledgable on this biological clock difference and the taxing the tegus go through in regulating to our schedules. In the wild, golds, as most tegus, brumate during our summer (their winter) and breed late fall (ours). Yet most CB tegus in the US are bred late spring/early summer with births being anywhere from late June to late September into October.
Thanks for the discussions!
Take it easy!!!
Greg