# Can I brumate my blue tegu?



## TR3S (Jul 6, 2021)

Hi, good day! I'm new here. Been keeping my tegus for over a year now and I'm planning to breed my male blue tegu to a red.

Based on what I read online, blue tegus doesn't need to brumate if you want to breed them, because they are naturally found near the equator where the temperature doesn't go down as low. I just set his, day light timer from 12 hours a day to 8 hours a day for three months.

However, I brumated my red tegu for three months. I live in a tropical country so I used a makeshift "brumator" using a peltier cooler with heat sinks and fans, the cooling chamber stayed below 20*°*C (68*°*F) throughout the entire duration.

Last March, I tried to introduce them and left them together for around a week. I can see that the female was interested in breeding, she was dragging her cloaca all around the enclosure, yet the blue male doesn't show any interest in breeding. In April, I tried to place the male again in the red's enclosure, but now both doesn't show any signs of breeding behavior. Last month, around first week of May, I tried to introduce them again, but this time the male is pursuing the female, and sadly the female shows no interest. But I'm still hoping that there was a successful lock, there were times I saw the blue is on top of the red, but haven't saw an actual copulation. Now, the female does not look gravid or showing any signs of nest building.

It seems that their "breeding season" are not matched; that's why I plan to brumate both my blue and red with the hopes that I can successfully breed them next year.

So with all that said, should I brumate my blue tegu? Is it safe for a blue tegu to brumate at the same temperature as the reds?

Thank you in advance!


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## Roadkill (Jul 6, 2021)

Pretty much everything about blue tegus is fiction. People have from the beginnings made up stories about them....but NO ONE has ever verified if any of them are actually true. The closest was a breeder who had records from exactly where they imported them from in Brasil....except they were known to be an introduced pest there. So everything about them not brumating, being from the equatorial region, etc., etc., is made up, mere assumption (heck, had one guy tell me last month they were in fact high altitude Argentina....people just can't seem to stop themselves from making up stories about them). Considering the difficulty you are having, I'd recommend you try brumating your tegus at the same time, however I would recommend a slow, gradual reduction in photoperiod over a sudden change. From my research, it's the continual changing of photoperiod, more than the photoperiod itself, that induces the changes towards brumation.


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## TR3S (Jul 7, 2021)

Wow! Thanks for the info


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## Debita (Jul 16, 2021)

Hey @Roadkill.....My adult male (B/W) was semi-brumating for a few months at the beginning of the year, and has now gone deep under for at least a month. Any ideas why his clock is off, or whether I should do anything about it?


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## Roadkill (Jul 21, 2021)

There could very well be a number of varying, unrelated things that could be at play here. For one, he may not have been brumating at all: certain illnesses will express as tegus being less active, losing appetite, and spending a lot of time sleeping. The display given....looks a lot, to the less experienced, to be....brumation. So...how does the average hobbyist go about determining if it is brumation vs an illness?

But let's go with that it was brumating. We see a lot of people say brumation is governed by an internal clock, that we cannot do anything to inhibit or induce it, it will happen on its own and there's nothing we can do about it. Well, in comparative physiology research, there are two basic forms of hibernation/brumation: obligative and facultative. Obligate hibernators/brumators ARE entirely governed by an internal clock, no outside signals can influence this, they go dormant at basically same time every year. And this is what a lot of hobbyists think is what happens with tegus...but it's not because if this were the case, ALL tegus would still brumate on their native South American seasonal cycle. We'd see them active during our northern hemisphere winter, dormant during our summers. Facultative hibernators/brumators on the other hand, are those animals who's dormant period is regulated and influenced by external signals (the scientific name for these is zeitgebers). Something clearly influences their cycles so that they adjust their dormant period to align with their new environment's winter season. Therefore, tegus are facultative brumators. Having said this, this doesn't mean as soon as you move a tegu from one hemisphere to another that they will immediately adjust to their new seasonal cycle. I've seen many cases of imported tegus maintaining their native seasonal cycling for a year or two, so this implies that there IS something of an internal clock, that contributes to a latency in response so that their brumation timing seems out of whack.

So, if we have very young tegus who are possibly expressing brumation in an off-season manner, I would take this as evidence that these are not likely "locally sourced" animals. If it's in an older tegu, one that has been on regular cycles prior, then I would suspect either illness or something has disturbed their internal clock to put them out of synch.


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## Debita (Jul 22, 2021)

So, from what you're telling me, it sounds like my 4 yr old is just finally settling into his routine, after being removed from his environment in the everglades in Florida. (I got him at a year old from Rodney Irwin at Tegus Only.) He's so deep down right now that I really don't want to interrupt him because this is the first time he's actually brumated, by definition. Mostly, he's just gone down for a maximum of 10 days and he did that this last winter. I increased his daylight hours and temps and he did the opposite - burrowed in and emerges only for water. His eyes are clear and weight looks good.

I think I'll leave him be, but should I change his lights and temps back to be shorter and colder? Do I entertain it, or try to pull him out of it by disrupting it? 

Thanks for the insight - that was a lot of info.


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## Roadkill (Jul 24, 2021)

This may be an all together different thing, though. Tegus are also well known for avoiding thermally inappropriate conditions: not only brumating to avoid the cold and resource restricted winter, but hunkering down and burying when things get too hot. I'm not saying for certain this is what happening in your situation, but it may be part of it. We see a LOT of information, here and elsewhere on the internet, from various breeders, hobbyists, etc., on things like what the basking temperature should be, sometimes what an evening temperature should be....but I rarely see anyone aside from myself state what should be obvious: what temperature is your tegu? Tegus are not passive physical black bodies that, like a thermal cork, bob around without influence in their thermal environment. They have some volition in their thermal regulatory ability, but very little ability to do anything for dealing with the extremes other than avoid them. Tegus appear to like to function around the same body temperatures as a standard mammal. If they're more on the negative end, they will spend more time basking. And while they may like to achieve a body temperature of ~35-37degrees C...those temperatures are close to the upper lethal limit of nearly ALL vertebrates: 40-41 degrees Celsius. Their body temperature goes any higher than this and they are going to die. And here's a little tidbit a lot of info that few hobbyists grasp: tegus and other reptiles display what is called a hysteresis with regards to warming and cooling - a disparity in the rates of each (they warm at a rate faster than they cool off). 

Here's a basic hysteresis curve (it's actually for elastic properties, but let's say in place of Tension we put Temperature, in place of Force we put Rate)





One way to look at this is it helps them to remain warm longer and avoid losing heat. Now most of such curves are empirically derived by measuring the respective parameters during a warming and cooling cycle, and the two points reside where the limits of the cycle were reached (so the drawn lines would represent the "path" experienced by the animals as they were warmed and cooled). However, very interestingly a particular study decided to look not at the whole animal but at particular components of them (such as the blood, arguably a very large reservoir of thermal energy in an animal), and at a dynamic system without the neurological control, and found that in reptiles this hysteresis expanded beyond the boundaries measured with the whole living animal. So what am I getting at here? This gives us 2 conclusions: much of this warming and cooling dynamic is an intrinsic thermal property of the tissue and does not reflect physiology or control (ie. it's going to happen whether the animal likes it or not, it's sort of beyond their control) and that while reptiles take advantage of this differential cooling and warming, it can also work against them. When we compare with the hysteresis of intact animals, particularly at their upper thermal limit (which I've guessingly put in as the blue dot in the diagram) we see something we didn't expect - their own tissues will continue to readily upload heat against the animal's "desire", it can actually push them into lethal limits (sure, this makes sense with higher temperatures, but it also means that at temperatures near their upper limit it can drive them there too). So if a tegu's enclosure is mostly in that upper thermal range....they're going to do what they can to avoid it once they're in that range. This is why when I'm often helping hobbyists troubleshoot what's going on with their pets and the enclosures they keep them in that I've given up using the proverbial temp gun and use a thermal imaging camera so that they can see and better understand the whole thermal environment. We want our reptiles to get warm and function properly, but part of that functioning properly is guaranteeing they have cold zones to escape to in order to behaviourally thermoregulate (sure, many people do measure a cold region in their enclosure...but is it actually large enough to accommodate the whole animal?). People may not realize it, but this is one of the greater reasons tegus need such large enclosures, so as to provide a complex enough thermal environment.


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## Debita (Jul 26, 2021)

OK - so given that info....I'm thinking that I'm doing well with his ability to thermoregulate, because he has a large warm (4X7.5') enclosure that is connected via a tunnel to a completely separate enclosure (a 5x3' - that has no heat in it at all) where he is pretty much subject to our room temp - somewhere in the low 70's. He goes over there off and on, and burrows in occasionally, but opts to mostly live in a wooden hide that's in the warm enclosure. That's where he's been brumating (I assume it's brumation) for about 1.5 months now. He comes out for water, peeks at me and goes back under after about 10 mins. Some days I don't see him at all, but he looks good. This is the first time he's done this behavior in the 3 years I've owned him. He's had little to no brumation prior to this.

Would you encourage activity, or leave him to his sleep in the hopes that this has been a long time coming and is a good thing despite the timing of it?

Again, thanks for your time.


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## Roadkill (Jul 26, 2021)

Forgive me but I'm going to assume you don't have the fortune to have much in the way of equipment to gauge metabolism in your tegu (while I'm a nerd and have an oxygen gas analyzer, CO2 gas analyzer, polygraph with amplifiers and filters for nerve, heart, and muscle recordings, sitting around at home....I wouldn't expect anyone else to...) but in your situation I'd still want to check something to make sure this wasn't a health issue. If possible, monitor its body temperature as often as you can (top of the head and side of the belly would be good locations) and while I can understand you not wanting to disturb it that often in case it is brumation, I'd want to weigh it on about a weekly basis. I'd have to dig up some old data to be sure but I'd think anything more than about a 1-2% drop in body mass/week would be an indication that this is not likely brumation.


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## Debita (Jul 30, 2021)

Good advice - thank you so much.


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