Hibernating your tegu
I’ve been seeing a lot of messages with people talking about their tegus preparing for hibernation, or people looking at inducing it. There are a few things that I think tegu keepers should be aware of in order to hibernate their animals with the least chance of complications. What tegus will do in the wild is a lot different than what they will do in captivity, and a lot of these differences, when not taken into account, can lead to lethal consequences in improperly prepared animals. Furthermore, different species do different things during the winter season. The following information really only applies to Tupinambis rufescens , Tupinambis merianae and Tupinambis duseni.
First warning, food. I’ve heard of many that just stop feeding their animal and immediately chilling them for hibernation. Or, on the other hand, captive tegus will usually continue eating until dropping temperatures are too cold to allow proper functioning. This is highly dangerous, and likely will lead to the death of the animal (unfortunately, I know this from empirical evidence, not theory). Digestive enzymes do not work properly at lower temperatures, and food retained in the gut will spoil and rot before it is properly digested, leading to the death of the animal. In the wild, tegus undergo spontaneous aphagia (they stop eating) approximately two months before fully entering hibernation. They don’t stop all at once, but cut down on the amount of food and frequency of eating for the first month, and basically stop eating all together for the second month. During this time, the average daily body temperature (which is roughly equal to their burrow temperature, not their active body temperature) drops from around 30° C to about 17°C (at a decreasing rate of 1°C for every 3 days for the first month, 1°C for every 2 days of the second month) while photoperiod decreases roughly at a rate of 1 minute every 2 days.
The deepest period of hibernation roughly lasts only about 1 month, with an average burrow temperature of 17°C. The arousal period is not sudden, but faster than the entrance period. Temperature increases at roughly 1°C per day, but photoperiod increasing at the same rate it decreased, at roughly 1 minute per 2 days.
Second warning, burrow humidity. It appears the main reason wild tegus hibernate isn’t so much temperature, but water availability. Winter is the driest season of the year in South America, and without water, besides dehydration, there’s no food available either. The burrows that they retreat to are generally much more humid than ambient. Your dormant tegus will lose a lot of water simply through breathing, so it is a good idea to keep the relative humidity of their burrow quite high.
During the hibernation period, a lot of keepers offer food. I highly do NOT recommend this, as stated above, if temperatures are not high enough, this can lead to serious complications. However, at the same time, most keepers are likely unable to get the animals’ burrow temperatures down that low, and therefore what their animals are doing is likely not fully hibernating. If you see a lot of activity from your animals during the period of hibernation (ie. Going in and out of the burrows daily), it is probably safe to feed them a little. If activity is only sporadic (once every few days or so), it is best not to feed them. Always, however, have fresh water available.
Tupinambis teguixin , Tupinambis quadrilineatus, Tupinambis palustris and Tupinambis longilineus are not true hibernators and therefore do not need as much manipulated husbandry, or radical changes. A slight reduction in temperature (maybe roughly down to 25°C), lowering of humidity, and decrease in food frequency and quantity should be all that is needed to simulate their winter period.
Thanks for this Tupinambis.
A couple of questions to follow on.
Providing that the animals are properly prepared, i.e. have empty stomachs and are kept well hydrated etc, do you see any problem with hibernation at a lower temp than 17C/62F ? (I have merianae from Agama Int.).
Also, working on the premise that I can control whether hibernation occurs or not, by manipulating daylength and temps, do you think I should hibernate my tegus?
Basically; I would like to go for it if there is a fair chance that they might breed next year?
They are around 15 - 16 months old now, the male is currently about 3 feet and the female 2 1/2 feet in length.
If I don't hibernate, they should be at/approaching adult size by late spring/summer 2006, but if I do, they may be a bit on the small size ....
It may be that I'd be better trying to keep them going this winter, ready to hibernate next, and trying to breed in 2007?
Thanks for your help
They can certainly go lower, I've done so in the lab. However, I wouldn't want to push it lower than maybe 10 degrees C.
Whether you should or not depends on your point of view. It is part of their natural cycle, and it certainly helps induce breeding. On the other hand, it is certainly easier and less "worrying" to just keep them active all year round (I don't want to make it sound like hibernation is dangerous at all times, just that when done improperly it certainly be - and I'll further admit, I'm very conservative/strict when it comes to hibernating my animals, you don't want to know how many I've killed in my research figuring these things out by trial and error :oops: ). There is one thing that I think many keepers overlook, though - hibernators live longer than all-year-round active lizards (provided the hibernation didn't harm them).
Whether yours will successfully breed or not is kind of hard to say. Males seem to have to reach not only a relatively decent size, but some evidence also claim a certain age. Yours would just be roughly reaching the age threshold. Females, on the other hand, seem to predominantly require a minimum size level be reached before they will breed. That's roughly 1.5-2 kg's. The thing to keep in mind is mainly if the female is ready, as it is hardest on her. After breeding, she'll be depleting her fat reserves to provide nutrition to the eggs, and sequestering a LOT of calcium from her own bones to provide shells for the eggs. The process is rather so profound and quick, it can be shocking. I've seen it go from where on one day the female looks full of health, all firm and well shaped, full of eggs, overnight lays the eggs, and the next morning the female looks like Thanatos is calling, not only has the abdomen "collapsed" from lack of filling volume (the eggs) but other sites of fat deposition (the tail, a bit in the hind legs, around the neck) also "sink in". If you think your female is nice and plump, I'd say give it a try. If, on the other hand, you think your female is either not massive enough or simply looks to thin, I'd avoid breeding her.
Thanks Tupinambis. With regard to hibernation, I'll see how my animals progress over the next few weeks. I'm not too worried about it because I've done this with quite a few species before, but not tegus....
Thanks for the tips about breeding weight/condition in females. Its always good to have a guide weight....
I am not educated on the subject, but doesn't it get cold in Argentina in the winter, at least enough to get snow? I know that when Bert was choosing bloodlines, he was aiming for the heartiest and most cold tolerant of the species and his winter temps in Alamaba get down below 0 degrees Celsius.
Originally Posted by tupinambis
Maybe he can shed some light on how they stay alive all winter long, cause he leaves all of them outside to hibernate.. Hmmm.
OKay... i just got an email back from Bert and he said that the ground temps always stay around 10-15c in the winter time, but they can take drops to 1c for short periods of time.
I guess this winter, i will need to bury a thermometer in the ground and find out how low they will need to be in the ground, in order to maintain good temps, since i will be laying mesh under the surface, to keep them from digging themselves out of the retainer. This is all a big ol learning experience for me.. having fun though..
Correction: the ground where he has his tegus only gets down to 10-15. That is NOT a universal law. It changes depending on latitude, longitude, duration of sub-freezing temperatures, water content of soil, angle of incidence of the sun, etc, etc, etc, etc. NEVER assume that because someone else in your country is able to leave theirs outdoors all winter that it will be safe to do so in your area as well, always check first. I'd advise you to get a digital thermometer with Min/Max memory as I'm pretty sure you aren't going to want to be up around the time that minimum temperatures are usually reached. Or even better, if you can afford a temperature data logger such as an iButton (although I abhore the company that produces these) then you can get an even better idea of the temperature profile that your tegus would experience in your area.
So I'm getting my tegu soon, and I'm wondering two things, first, winter doesn't occour the same months here as it does in Argentina so do the hibernation periods here matter? Like would you put your tegu in hibernation during winter here, even if its indoors? Also, if you don't put your tegu into hibernation the first year, can you do so later on, or would this mess up its internal clock? Thanks
It would be best to hibernate the animal in regards to the hemisphere where it currently inhabits. It is unclear what cues the animals use for hibernation, some appear to be uncontrollable (ie. atmospheric pressure, angle of incidence of light, etc.) and if you tried to hibernate outside of the actual time (ie. tried to maintain the hibernation schedule of South America upon an animal living in North America) it would likely cause some problems.
If you don't hibernate it the first year, you can still hibernate it later years.
If you DON'T hibernate, that will screw up the internal clocks (for hibernating species, that is).
What if a Tegu was purchased while in the first 2 months of hibernation, can I bring him out? What would happen if I put him under normal conditions?