# Roadkill: Breeding and Hibernation



## nepoez (Mar 8, 2017)

Hi Roadkill, and anyone else who knows things!

I haven't been here in a while because I left the country for 2 years. Now I'm back and have a new cage built(will build even more later) I'm getting back into tegus. I currently have a colombian but I plan to breed Salvador(or black n white, red ,etc) tegus as a hobby but have heard of some conflicting info regarding breeding and hibernation.

As a pet owner I don't want a pet that's sleeping 7 months a year. What's the point. So I want to know if I can prevent hibernation in a healthy way. I heard if the enclosure has no exposure to real sun light they will not hibernate. If that's the case, I will do that. But then I also heard if they don't hibernate they will not be able to breed. Does anyone have any input on these claims?

Ideally I want to be able to breed them, but still have a pet all year round. So if this is not possible I will not bother with my plan.


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## Roadkill (Mar 9, 2017)

I'm afraid that what you're looking for is a clear cut, black and white answer when really there isn't one.

Tegus are clearly not obligative hibernators (meaning a type of hibernator that will enter the hibernation state regardless of environmental cues, governed pretty much exclusively by genetics - if this were indeed the case, pet tegus in the northern hemisphere would still hibernate in synchrony with South American seasons) and so are influenced by zeitgebers; external, environmental cues that cause modifications to their physiology. The problem is there really hasn't been any thorough, definitive studies to determine what they may be and the extent to which they cause the hibernation response. From my own research, I can tell that contrary to what most people seem to think, the initial physiological changes (in wild tegus) start taking place well before we see any real outward expression. My interpretation of this is that about the only thing that could be causing an influence at that particular time is a change in photoperiod. Now here is where I always stress my point, and most seem to always get the wrong message: what I think they are responding primarily to is the CHANGE in photoperiod (and most hobbyists interpret this as meaning a short photoperiod - which is wrong) - I don't think they're hibernating/preparing to hibernate because the photoperiod during peak winter is 11hrs of daylight (or shorter, depends on the geographic location), I think the initial zeitgeber to influence a change towards hibernation is that CHANGE, of the days now getting shorter in duration (where I was doing my studies that initial change was something like 15 seconds shorter each day - it doesn't sound like much but again that's if your focusing on the measure of the length of the photoperiod as opposed to the fact that the photoperiod is changing and doing so by getting less). However, this being said, it has to be realized that sunlight is an extremely complex signal. I've only indicated 2 possible variables (length of photoperiod, change of length of photoperiod) when there could be many (intensity, angle of incidence, length of thermal window, time of adequate thermal potential, etc.) - it may be any single one of these variables, it may be several, it may be a relation between several, we really don't know. This is where the idea of restricting real sunlight comes in - if you can completely prevent them getting any real sunlight cycle exposure, this is probably cutting off their most powerful environmental signal. This being said, I still think temperature is another large factor, but not the strongest factor and not an independent factor. However, once again, I stress we really don't know that well, and while playing with these to try to prevent hibernation is likely to increase the odds of preventing your tegu from entering hibernation, I cannot guarantee 100% it will be successful.

Now, one of the things hibernation does for them is help reset their circannual rhythms, primarily their hormone cycles. It's their hormone cycles that govern whether they will successfully breed. I've heard people claim they bred their tegus without them hibernating, so it appears it can be done. However, my experiences in this matter would tell me to use caution in the fact that very few people have any inkling what hibernation in tegus actually is. Whether these tegus were or were not hibernating is up to interpretation. I would say, though, that by not hibernating you reduce your likelihood to successfully breed. I wouldn't argue that it's impossible to breed them without hibernating first, just that it makes things less likely.

However, this also raises another question which you hint at; can one inhibit hibernation in a healthy way. Again, there is no definitive evidence one way or another. We know that hibernation is a state of depressed metabolism, they slow down their physiology, so theoretically it makes sense that those tegus that hibernate successfully should live longer (think of hibernation as pausing their time clock for awhile and that each tegu only has a set amount of time they can live). Again, I have nothing to back this up concretely but I do have some anecdotal "evidence". Asking around, it seems common among tegu hobbyists that the average lifespan for Salvator tegus is around the 10-15 year mark. Just recently there was a post where someone had mentioned their tegu was 14 years old and showing the need for special care due to geriatric rundown. Now, I'm not exactly a specialist in animal longevity, but my formal training is in comparative physiology, and looking at the trends across other reptiles, this strikes me as premature. An animal that's an ectotherm, that hibernates, and reaches a size that tegus do to my eye should be living quite a bit longer than that. I honestly think most tegus die an early death because most people don't realize their husbandry is actually deadly, they mistakenly think they're treating their tegus very well. I see a lot of overfeeding, unbalanced diets, lack of exercise, and little hibernation - leaving out the hibernation, the rest of that is a well known recipe for heart disease and otherwise just general poor health in humans. To this claim I have a little shred of evidence - in my collection I have a tegu surrendered to me from my old lab. Now, if this guy was one of my original (ie.first batch I ever worked with in that research setting) tegus, that places him at 18 years old. Even if he's from the most recent clutch we worked with, he'd still be 13-14 years - and he's going strong, no sign of geriatric deterioration at all. This in spite of the fact that until he was retired he had a life of "abuse" (I don't mean to sound like he was beaten and deliberately caused harm, but he was a research animal, he underwent numerous surgeries, and it's very clear that all the years he wasn't under my care he got a bad diet because his front limbs are malformed and exhibit reduced motion). The years under my care I CAN claim a much more balanced diet, routine fasting periods, and annual hibernation. From what I see, my routines work. Having said all this, I will be the first to say that not hibernating them properly is also hazardous to their healthy (in fact, can be outright deadly).


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## nepoez (Mar 9, 2017)

Thanks Roadkill for your detailed reply. I really appreciate that. I assure you that I read every word and your time is not wasted. I'm a slow learner but I'm here to learn so please bare with me as I will probably have more questions as time passes on. Assuming I stick with this path I am planning I am also going to share what my observations are so people who are curious about this topic will have some data available to them. Hopefully you will be here for a while!

A few years ago I had kept my tegu hatchling(Salvador) in the basement. The basement had no windows, temps are 75-90 ambient depending on which side of the cage and basking is up to 135 depending which spots, humidity is 75%-90% depending on when I water the place. The cage is 8x4x4. With Soil/Sand/Clay substrate over 1 feet deep. The environment is consistent all year round. He did not hibernate at all, he would get up and roam the cage for about 5 hours non-stop. So that's very active. But I had to leave the country so I had no way of telling if this was just a 1-off thing that he skipped his first winter hibernation, or if it's due to the lack of CHANGE in environment. Too bad I could not keep it longer to get a better indication.

Right now, besides the colombian. I also have a red which I bought in OCT/NOV 2016. It did have exposure to sunlight because my brother in-law kept it for me while I was away, it is currently hibernating and had not come out at all. If he isn't dead already and comes out, he will be in my environment with no exposure to real sunlight. I will let you know what happens the next few winters. If he hibernates or not in my environment with no real sunlight. It would be interesting to see him not hibernate for a few years, then one year I uncover the windows and see if he hibernates.

Now, if he does hibernate even in my environment, I do plan to keep my environment constant still. I don't plan to lower temps, turn off light etc. Do you think that is a bad thing to do for a hibernating tegu?





Roadkill said:


> I'm afraid that what you're looking for is a clear cut, black and white answer when really there isn't one.
> 
> Tegus are clearly not obligative hibernators (meaning a type of hibernator that will enter the hibernation state regardless of environmental cues, governed pretty much exclusively by genetics - if this were indeed the case, pet tegus in the northern hemisphere would still hibernate in synchrony with South American seasons) and so are influenced by zeitgebers; external, environmental cues that cause modifications to their physiology. The problem is there really hasn't been any thorough, definitive studies to determine what they may be and the extent to which they cause the hibernation response. From my own research, I can tell that contrary to what most people seem to think, the initial physiological changes (in wild tegus) start taking place well before we see any real outward expression. My interpretation of this is that about the only thing that could be causing an influence at that particular time is a change in photoperiod. Now here is where I always stress my point, and most seem to always get the wrong message: what I think they are responding primarily to is the CHANGE in photoperiod (and most hobbyists interpret this as meaning a short photoperiod - which is wrong) - I don't think they're hibernating/preparing to hibernate because the photoperiod during peak winter is 11hrs of daylight (or shorter, depends on the geographic location), I think the initial zeitgeber to influence a change towards hibernation is that CHANGE, of the days now getting shorter in duration (where I was doing my studies that initial change was something like 15 seconds shorter each day - it doesn't sound like much but again that's if your focusing on the measure of the length of the photoperiod as opposed to the fact that the photoperiod is changing and doing so by getting less). However, this being said, it has to be realized that sunlight is an extremely complex signal. I've only indicated 2 possible variables (length of photoperiod, change of length of photoperiod) when there could be many (intensity, angle of incidence, length of thermal window, time of adequate thermal potential, etc.) - it may be any single one of these variables, it may be several, it may be a relation between several, we really don't know. This is where the idea of restricting real sunlight comes in - if you can completely prevent them getting any real sunlight cycle exposure, this is probably cutting off their most powerful environmental signal. This being said, I still think temperature is another large factor, but not the strongest factor and not an independent factor. However, once again, I stress we really don't know that well, and while playing with these to try to prevent hibernation is likely to increase the odds of preventing your tegu from entering hibernation, I cannot guarantee 100% it will be successful.
> 
> ...


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