# night time lows.



## Anyfoot (Dec 10, 2017)

One aspect of tortoising I've neglected to look at is lower temperatures at night. 
I just don't bother with a drop in temps with my redfoots or homeana. Maybe this is an area I need to look at. 
For my radiated I've got temps dropping at night. 
For the last few weeks I've been watching the weather in Madagascar(Toliara). Basically at this time of year it's around 86f/91f and 60/70% in the day and 75/80f and 80/90% at night. 
I'm curios of what impact having night time lows has on our tortoises. 
Also would the micro climates that the babies live in be more stable through day and night?


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## CharlieM (Dec 10, 2017)

I’ve used a temp gun in the early morning and my tortoises that dig into the mulch substrate under a hide are 10-15 degrees warmer than the nighttime low. My tortoises can go into a hide under a covered and enclosed area. If I add a tarp over the entire enclosure the tortoises stay even warmer. The ground holds heat during the rare and brief cold snaps we have in Florida.


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## Markw84 (Dec 10, 2017)

Anyfoot said:


> One aspect of tortoising I've neglected to look at is lower temperatures at night.
> I just don't bother with a drop in temps with my redfoots or homeana. Maybe this is an area I need to look at.
> For my radiated I've got temps dropping at night.
> For the last few weeks I've been watching the weather in Madagascar(Toliara). Basically at this time of year it's around 86f/91f and 60/70% in the day and 75/80f and 80/90% at night.
> ...


Craig,

The best data I've seen on this can be extrapolated from extensive studies made for passive heating/cooling systems using the thermal mass underground to more efficiently stabilize systems. Also lots of good agricultural reports on ground temps worldwide that I've read.

It has been established that the ground temperature just 0.5m below surface is quite stable even with very wide daily air temperature swings. At just 1m deep the temperature averages =/- 2° of the daily average air temperature. There is a lag of just over a month as the seasons and average day temperature changes. At just 0.2m below surface, the ground temp stays within about 5° of the daily average. So with your figures above, with a high of 88° and low of 77° we would see an average daily temp of about 83°. A tortoise in a shallow pallet under a bush would probably experience pretty stable temps overnight in the range of 80°-83°.

I've looked at data for areas for radiata, pardalis, sulcata, and platynota in the past. All are amazingly similar in what the average ground temps would stay. There is a difference in the width of air temp high/low swings, but the average temperatures and therefore ground temperatures are interestingly in the same ranges.

If you think about it... We have found almost all tortoise species eggs are best incubated at a quite narrow temperature band. And that would indicate optimal temperature for best metabolic function!!


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## Tom (Dec 10, 2017)

Markw84 said:


> Craig,
> 
> The best data I've seen on this can be extrapolated from extensive studies made for passive heating/cooling systems using the thermal mass underground to more efficiently stabilize systems. Also lots of good agricultural reports on ground temps worldwide that I've read.
> 
> ...



You remember how when you were a little kid and a beloved family member (Mom, Dad, Grandparent, Aunt, Uncle, etc…) would read you your favorite bedtime story. Remember how good that felt?

That is how I feel about the story above. I just love it every time I read it.

When the cynics ask: "Why do you keep them 80 degrees at night? Its not 80 degrees in the wild every night…" I just remind myself of my favorite tortoise bedtime story where Mark explains the concept of ground temps vs. weather station readings from 2 meters above the ground in open areas with no kind of cover.


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## Tom (Dec 10, 2017)

Anyfoot said:


> One aspect of tortoising I've neglected to look at is lower temperatures at night.
> I just don't bother with a drop in temps with my redfoots or homeana. Maybe this is an area I need to look at.
> For my radiated I've got temps dropping at night.
> For the last few weeks I've been watching the weather in Madagascar(Toliara). Basically at this time of year it's around 86f/91f and 60/70% in the day and 75/80f and 80/90% at night.
> ...



I don't know RFs, but from what I have read of other people's experiences, they thrive without a big drop in night temps.

For all my tropical species (Sulcatas, leopards, stars, pancakes…) I always have a night drop, but usually not below 80 for little ones. In summer, I let ambient creep into the mid 90s in my enclosures, and in winter ambient will creep into the mid 80s during the day. At night, year round, temps drop to about 79 at night. I don't have a lot of radiata hatchling experience, but I just baby sat some for a month, and this worked well for them too.

I recently got to tour the facility of a friend who breeds radiata, and he told me that he lets the adults drop down in to the mid 60s at night and has been doing it that way for years.

To me, discussions of drops in night temps are most relevant in discussions of species that would experience these significant drops in the wild. Basically any species from a temperate Mediterranean climate. Testudo, Gopherus, SA leopards and Chersina. When indoors, I let Testudo species hatchlings drop into the high 60s or low 70s. Daytime ambient for them will be around 80 in winter and sometimes low 90s in summer. I like them to experience the seasonal variations that their species would be adapted to dealing with in the wild.

This discussion always seems to gravitate toward talking about what night temps tortoises can survive. People will come on to the thread and relate stories about how cold they let their tortoises get and how they are fine. There is no doubt that tortoises can survive some pretty cold temperatures. Even tropical species like sulcatas can survive cold temps. But my question is always: What temps are _optimal_ for a given species, vs. what temps are survivable. It is a tough question to debate. If I keep mine one way, and they all seem fine, but another guy keeps his differently and they all seem fine, who is "right"? How do we measure this? Are mine more "fine" than his? Or vice versa? What is his definition of "fine" vs. mine?

Speaking only about sulcatas and leopards, I kept them much cooler at night in years past, and they all survived and seemed fine. As I studied more and more about their lives in the wild, I decided I didn't think they should be so cool at night, and I made a change in how I housed and heated them at night. They had always been "fine" for all those cold years, but when I started keeping them warmer at night I saw a huge change for the better. Appetite and activity were much better. Growth and reproduction improved. I liked the results I was getting. Everyone I know who used to keep their sulcatas colder at night, but switches to warmer nights, loves the results. No one I've come across ever wants to go back to the cold way. The only people I hear saying that they think its fine to let them be cold are people who don't want to spend the time, money or effort to keep them warmer, and have no idea what the difference is because they've never tried it.

Speaking about russians and CA desert torts, I found a big difference in their behavior, appetite and overall health when I started keeping them a little warmer too. We tend to have large temp swings from day to night here. 80 degree sunny days, are frequently followed by nights in the low 40s to high 30s. My tortoises did okay in their shelters where night temps would drop into the 50s during these cold nights, but they were usually lethargic and slow to get started the next day, with low appetite. Too many cold nights in a row, and they would stop eating entirely. I'm talking about spring and fall, not winter when they want to hibernate. I started heating their night boxes a little bit, keeping temps in the low to mid 60s, instead of low 50s, and I saw a huge improvement in their behavior and appetite. They still got a night temp drop, just not as much of a drop, and they did "better".


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## Anyfoot (Dec 11, 2017)

Interesting. 

So we know that weather stations don't give out the reading we tortoise enthusiasts require for babies, for example their humidity readings are air humidity reading which are probably way off the micro climate reading we are after for baby tortoises. What it does give us are the extreme temps that occurs within that region, so we can get an average temp to work with. As for humidity, is it safe to assume the higher readings that weather stations give out are a good starting point. 
For example in Bahia(SA) during the day at this time of yr the air humidity is around 40% and at night 80/90%. We all know that the micro climates are going to be way above the 40% air humidity readings and I would have said 80% would have been a good starting point. 

What I'm trying to work out is in most parts of the world there are higher temps and lower humidity in the day than at night according to weather station readings. But these readings are kind of irrelevant with our microclimates. 
In temperate climates where there can be bigger swings in temps for longer periods it's a different ball game. 
So assuming the micro climates are more stable than weather station readings, I mean it's not going to be 92f down in the undergrowth in deep deep shade in the day and equally probably doesn't drop to 75f at night. You would expect this micro climate to be let's say 80/85f constantly within a tropical climate. Obviously humidity is higher down in the undergrowth than air readings. 

Its all coming back around to my obsession on how they grow. We've all established that warm and humid is the best climate for smooth growth, But fir example does a baby Leo venture out into the sun in the day when it's 95/100f and not even 19% humidity. (Look at Juba weather readings) If they do venture into this hot dry climate in the day, how long for, is it 1hr just to warm up,but do they need to warm up if micro climates are more constant anyway. 
Maybe they do come out in day, but there's no growth whilst they are active and growth commences at night when at rest in the warm humid climate. Or maybe they just stay in the warm humid micro climate for months, years maybe, but then where's D3 come from, has to be diet at the earlier months, years.


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## Tom (Dec 11, 2017)

I don't know if we know when growth occurs. I don't know.

I'm reminded of a TTPG presentation where the speaker related his experience looking for cuora in the vietnamese jungle. He said it was so hot and humid at 6 feet off the ground where they were walking and standing that a person could barely breathe or move. Temps were near 100 degrees F. He really emphasized how stifling it was and that walking just a few feet made them fell like heat stroke was eminent. He got down on hands and knees and was searching through the under brush and it felt cooler. He put his thermometer down there in some of the thicker brush near the bases of the trees and found temps in the high 60s. How is that even possible? Daytime temps were near 100 and night temps were in the 80s. But he had pics of the digital readout on his thermometer...


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## Anyfoot (Dec 11, 2017)

Could it be Precipitation(dew) from each morning keeping temps down at ground level.


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## Markw84 (Dec 11, 2017)

I don't think it is an issue of what part of the day growth is occurring most. It would make sense that when core body temp is close to optimal, and nutritious food has been consumed - that is when growth is occurring.

(Here's my current theory on this...) However, pyramiding is when the newly formed keratin that is being formed at the expanding growth seams is dried too much and cannot rehydrate. As it dries, keratin hardens and becomes stiff and non-permeable. We all see the new growth seams with our tortoises. The keratin there is softer. Next time you bathe your tortoise watch as the carapace dries on one with an active growth seam. You can actually see the scute dry off and the seam remain wetter longer. As this occurs, the seam will look much darker and visibly wetter than the rest of the scute. That new keratin acts differently. It takes on water more readily. In this stage, keratin swells with hydration. The growing seam needs to remain long enough in this state to allow that seam to fill in evenly for smooth growth. If it dries prematurely, the top of the keratin at the seam will no longer take on moisture when available and remain stiff. Additional swelling occurs only at the bottom of the seam and pushes downward. So the seam grows lower than the previous seam. = pyramiding.

Day time humidity is lower than night time because we always refer to 'relative' humidity. The warmer the air, the more moisture it can hold. So the same amount of water molecules present in the air will result in a higher relative humidity the lower the temperature. Once temperatures go low enough - you reach the "dew point". that is where the amount of water molecules in the air is the maximum amount air can hold at that temperature = 100% humidity. Dew will form as water precipitates from the air. Any surface that is just a tiny bit cooler than air temperature at this stage will become wet with "dew". That is why you see morning dew - the ground is slower to heat than the air as the sun comes up. The air temp is still at or near dew point, so the air releases water onto the cooler surface = dew. The more the temperature differential, the more "dew" and the farther from dew point (lower relative humidity) is required to still precipitate moisture from the air. A cold drink on the table forms moisture on the side of the glass even in very low humidity when the differential between glass temperature and air temperature is great. The insides of our tortoise enclosures form condensation as the air temperature of our enclosure is warmer than the glass window cooled by the room temperature.

In areas where tortoises live, and in times of the year when they are most active and growing, dew point is reached most every morning. With high humidity, that condensation effect occurs with small temperature differentials throughout most of the evening and mornings. So not only do our tortoise keep their shell moist burrowing in under brush, leaf litter, and into burrows, but they also emerge from these protected places and their shells are cooler than air temperature throughout the warmer parts of the day. So although relative humidity has dropped some (But not much in their part of the world) that differential between their shell temperature and air temperature will cause moisture to form on their shells. Keeping that new keratin layer hydrated. (As warm blooded animals, we never notice that effect ourselves. But an ectotherm lives with that temperature differential.) That is very different than the environment we provide for our tortoises in captivity. Unless we provide a humid chamber, our homes and areas most of us live are far too dry (relative humidity) and the air is indeed too desiccating on that keratin growth.

Just look at how your skin feels if you've ever visited the tropics. Our skin (keratin) does not even need lotion applied to keep it from getting dry and scaly looking! While at home, without lotion, I can start looking fairly reptilian!!

So I don't think we need to look at when growth occurs on a daily basis. Instead, it is that period when the new keratin expanding and we see active growth seams, when our tortoises are exposed to pyramiding. In captivity, that is year-round. In the wild, that is the times of year when the way they live in their environment takes care of hydration.


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## Tom (Dec 11, 2017)

Anyfoot said:


> Could it be Precipitation(dew) from each morning keeping temps down at ground level.



You mean in the tropical rain forest jungles of Vietnam? Its certainly wet down in the brush. I don't know how much evaporative cooling there would be with humidity already so high.

I'm reminded of a job I did in New Orleans in June a few years ago… Daytime highs were 100-105 night time lows were mid 90s. Fahrenheit. The lows. Mid 90s. Humidity was 95-100%. Anyway… We were filming nights and my dog had to wear a bunch of special effects make-up, so every night after filming I had to bathe him. One morning as the sun was coming up, I did his usual bath, dried him off and I draped the towel over a barbed wire fence to dry. Weather was sunny, 100+ degrees and no rain or clouds at all. We went back to the hotel and slept, then came back in the early evening for another night of filming. I went to retrieve the towel and it was still sopping wet after sitting in the sun all day. It was right where I left it and no one had touched it or gotten it wet. The water just couldn't evaporate out of the towel, even in full sun all day, because there was already so much water already in the air. I would imagine the air in the shadows of the canopy of the Vietnamese tropical rainforest would be even worse.


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## Anyfoot (Dec 11, 2017)

When we go on holiday to Mainland Spain, Spanish islands or Greek islands during July August or September time its blazing hot 30/40c and dry during the day, when the sun goes down it cools to a 25/30c and you sweat like a pig. The humidity is off the scale, it's literally like sticking your head in the vivarium, harder to breath. Mind you mines probably exaggerated with beer . 
Point is, even in the med it is super humid at night and up to sunrise. What I don't know is what is it like outside the 3 months I've mentioned.


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## Anyfoot (Dec 11, 2017)

From what your both saying, night time lows are more important than we think, because the very nature of lower temps at night increase humidity as long as there is moisture in the air in the first place, this in turn creates dew droplets on the carapace.


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## Markw84 (Dec 11, 2017)

Anyfoot said:


> From what your both saying, night time lows are more important than we think, because the very nature of lower temps at night increase humidity as long as there is moisture in the air in the first place, this in turn creates dew droplets on the carapace.


In my enclosures, the daytime temperature creeps into the 90°'s with the ballasts from the fluorescents and the basking floods heating the enclosure. At night, with the lights off the temp drops to 80° where the CHE holds it. The humidity then goes down to 80% daytime, and up to 95% at night as the temperature "cools". However, since our enclosures keep the tortoise at a stable temperature equal to the enclosure temperature, the effects I am referring to above are not in play. So I don't feel a night drop in our enclosures is at all that necessary. Because of the uniform temperatures we are providing, uniform, high humidity is important.

"In the wild" is a different story. The night drop to dew point is a way tortoises' shells can remain rehydrated with the drier daytimes. We work with a totally different set up parameters in our enclosures.

And it is not just the dew formation. The high humidity that is maintained while the tortoise is growing and "exposed" is important. Without visible drops of dew forming, the hydration effect still can be great as a cooler shell absorbs some moisture from the air. A tortoise emerging from hiding in the morning will be colder than air temperature. My platynota are most active at sunset and a few hours beyond. They retreat to their hides with their shells cooler than the air temps of their hides. In the wild, these are mechanisms that creates conditions that simply looking at temperatures and humidity from a weather station does not show. Nor does simply throwing a thermometer or hygrometer in a burrow or pallet show results that take these factors into account.


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## Anyfoot (Dec 11, 2017)

Mark. 

I agree weather stations are at best a starting point, and are just not a true reflection of our baby tortoise needs.
Take your point with night lows, our entire enclosures need to be that point where dew develops, hence, high humidity. 

I've plenty to think about again. 

Mark. There's one thing I need to get straight, and that is how dew comes about. I thought dew formed when 2 object of different temps clashed. So for example my warm tortoise wanders around its enclosure at 91f, when it goes to sleep in foliage at 79f it gradually cools down to 79f. The nightime low kicks in to 82f which is still higher than 79f where the tort is sat in foliage. So as 82f air meets 79f foliage there is Dew. My torts come out of the foliage with droplets on the carapace. That's either because the temp difference between air and foliage(and tort) is keeping the foliage moist with dew or it's because my foliage is still moist from when I first set it up 2 wks ago. I'm not spraying the foliage. Either my foliage will dry out or night time lows will keep topping it up with dew.


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## zovick (Dec 12, 2017)

Anyfoot said:


> Mark.
> 
> I agree weather stations are at best a starting point, and are just not a true reflection of our baby tortoise needs.
> Take your point with night lows, our entire enclosures need to be that point where dew develops, hence, high humidity.
> ...



Are any of you fellows familiar with the 2016 study by Heinrich and Heinrich published in the Journal of Exotic Pet Medicine which states that a daily heating and cooling cycle is required by chelonians to prevent pyramiding? Here is the final part of their article:

"CONCLUSION Chelonians are dependent on heating and cooling cycles for optimal metabolism and subsequent growth. Application of nocturnal heat increases growth rate and CSP incaptive-raised leopard and spurred tortoises. When designing captive environments, one must consider various species’ natural and phylogenetic histories. Although all nutritional and environmental variables need to be evaluated, heat cycles are of paramount importance for proper growth rate and shell formation. CSP may be reduced and ultimately eliminated as evolutionary requirements of a specific species are applied I in a captive setting."

Note that CSP above means Carapacial Scute Pyramiding.

Anyone wanting to read the entire study may email me for a copy of the article. [email protected]


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## Markw84 (Dec 12, 2017)

zovick said:


> Are any of you fellows familiar with the 2016 study by Heinrich and Heinrich published in the Journal of Exotic Pet Medicine which states that a daily heating and cooling cycle is required by chelonians to prevent pyramiding? Here is the final part of their article:
> 
> "CONCLUSION Chelonians are dependent on heating and cooling cycles for optimal metabolism and subsequent growth. Application of nocturnal heat increases growth rate and CSP incaptive-raised leopard and spurred tortoises. When designing captive environments, one must consider various species’ natural and phylogenetic histories. Although all nutritional and environmental variables need to be evaluated, heat cycles are of paramount importance for proper growth rate and shell formation. CSP may be reduced and ultimately eliminated as evolutionary requirements of a specific species are applied I in a captive setting."
> 
> ...


Thanks for the input here, Bill. I really value any experience and learnings you can share.

Yes, I am very familiar with this study and have studied it and their techniques quite a bit in the past. I do not agree with their conclusions and their research has several variables that were absolutely not controlled in the way they set up their experiment and study. One of the biggest is what I mention in the post above - that a drop in temperature automatically brings a rise in relative humidity. They kept all tortoises in an open top enclosure. The heating provided for the "night heat" group was therefore rather desiccating all night, while the "night drop" group had no desiccating IR exposure all night and an increase in humidity. They do not account for that, nor even seem aware of that in their study. Their results did not eliminate pyramiding. All tortoises pyramided in both groups. The night drop groups just experienced a bit less pyramiding. In my opinion, that was a result of the above effects. Their conclusion is pure conjecture and none of the results of their experiment support that conclusion.

Additionally, we/I have plenty of cases of smooth tortoises grown without night drop, but consistent humidity. They did not grow any smooth tortoises with their techniques. I was interested because it was a similar experiment to what I did with several of my sulcata groups about 20 years ago trying to figure out this pyramiding thing.


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## Tom (Dec 12, 2017)

zovick said:


> Are any of you fellows familiar with the 2016 study by Heinrich and Heinrich published in the Journal of Exotic Pet Medicine which states that a daily heating and cooling cycle is required by chelonians to prevent pyramiding? Here is the final part of their article:
> 
> "CONCLUSION Chelonians are dependent on heating and cooling cycles for optimal metabolism and subsequent growth. Application of nocturnal heat increases growth rate and CSP incaptive-raised leopard and spurred tortoises. When designing captive environments, one must consider various species’ natural and phylogenetic histories. Although all nutritional and environmental variables need to be evaluated, heat cycles are of paramount importance for proper growth rate and shell formation. CSP may be reduced and ultimately eliminated as evolutionary requirements of a specific species are applied I in a captive setting."
> 
> ...



Like Mark, I am also appreciative of every post you take the time to type up here. I read all of them with great interest.

I am not familiar with that study, but from reading what you and Mark have written about it, I see the same problem with this study as I do with so many others and with the people who argue against the style of tropical tortoise keeping that I advocate. My first hand results completely refute their conclusions and assertions, and so do the results of all the people all over the world who are duplicating this grand experiment. Also, the experiment in your post, and the people who argue these points with me, have never raised a tortoise the way I'm raising them, yet I have raised tortoises many times the way "they" typically advocate. I know what the results will be with "their" method, but they don't know what the results will be with "my" method because they have never done it. Makes it difficult to have a meaningful discussion when one party is completely ignorant of half the material being discussed.


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## Baoh (Dec 12, 2017)

Nighttime temperature lows/drops are a natural thing in any wild environment and with greater or lesser fluctuations at different points in a year for the same geographic area. It has benefits already mentioned. If eliminated, there often needs to be compensation in terms of maintaining smoother growth. Since the animals evolved over ages in that environmental situation, there may be other benefits aside from cosmetic effects and those hypothetical benefits could be lost if eliminating the drops (we do not know what we do not know).

With babies of jungle and near-jungle species, I tend to avoid real night drops for the first year or two. Of course, by the second year (for me), they are subadults. For adults of jungle and near-jungle species, I let them experience a night drop for practical reasons.

For more temperate species, a night drop is the way I have taken and would take it.

You are not necessarily incorrect to avoid a night drop. You are not necessarily correct to avoid a night drop.

As for lows in terms of tolerance, this will depend on a bunch of things. Species. Subspecies or locality. History of exposures allowed (huge, huge factor). There are few good reasons to explore an animal's limits of tolerance. That is more for knowledge-gathering than anything of benefit to the animal, although it is valuable to other animals in future applications or considerations. However, the rise of over-coddled animals is something interesting. Animals which experience an accidental 50-60-degree night and suddenly are weakened and experience rapid illness are a shame to see. Animals which are allowed to experience gradual exposures tend not to react like that. There is a tempering process that can be achieved if done with some intelligence (or luck for some that do not plan it, but that does not necessarily end well often). Hardened animals are more safe when an unforeseen event occurs. You have no express need to explore this, but there is a benefit. It is also cool to observe it. An excellent example that has been showcased here is Len's male sulcata (Walker). I have countless personal examples. The principles apply to any species of tortoise, although the extent varies with species and individual. It is not all-or-nothing.


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## Markw84 (Dec 12, 2017)

Baoh said:


> Nighttime temperature lows/drops are a natural thing in any wild environment .



@Baoh I do enjoy your posts and try to read every one I see to try to pick up and learn something. I value your expertise and experience.

I do have a question about the part of your post you started with and I included above. That is what I feel is misleading. It is so often, as here, simply stated as a simple fact and then used to justify night drops. Where I see this the most is with sulcatas to justify not, or minimally heating them at night in captivity.

Do you have some basis for fact that I am unaware of? My point in the posts above is that tortoises do not live where weather stations are positioned - above the ground. In the particular case of the sulcata, they live in burrows that are normally 2 - 8 meters deep. There are no night drops there. All the studies on ground temperatures show variations in daily temperatures become almost negligible at 0.25 m and below. I really find value in this discussion because I do believe it is a root of a lot of older misconceptions about how to keep tortoises.

To suppory my point, I will show just one of the dozens of charts I have on actual data for daily temperature values at depth. This is from a study done on the Island of Cyprus. It looks at one day that went from an air temperature of a low of 14°C (57°F) to a high of 32.5°C (90°F). So a mild day in the terms of our sulcatas but a temperature swing of comparable value. At 4" deep the temperature pretty much followed the air temperature with a lag of a few hours. That is in the open, unshaded soil. Not under a bush or any cover. However, even there, at 0.25 m (10") deep, the temperature only varied over the whole day from 22°C (71.5°F) to a high of 23.5°C (74.3°F) At a depth of just 1 meter, the variation over the course of the day is well under 1°C



248
And the temperature at depth always stays within a few degrees of the daily average temperature. In Cyprus this day it was 22°C (71.6°F) If we look at average temperatures in the Sudan, for example, where some of your tortoises come from, we see the following ranges year-round if we look at data from Galgani, Sudan which is near some of the remaining G sulcata populations in the wild:




So in their wild habitat, overnight low average never dips below 72°F throughout the year, and the daily average temperature (which ground temps follow) never dips below 85°F all year.

From this I can conclude pretty reasonably that retreating to a burrow, a wild sulcata never experiences a nightly temperature drop, and never endures temperatures below 80°F in their native range.


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## Baoh (Dec 12, 2017)

> Do you have some basis for fact that I am unaware of?



Well, there were all of the times I visited areas where I have found a number of species _in situ_ and where I found them during the day was of a temperature higher than where I found them at night. I have found tortoises in Europe, Central/South America, and Asia. The US, too, if we count Gopherus in this. I have yet to visit a place where the nighttime temperature of the tortoise at an activity nadir was equal to its daytime temperature at its activity apex unless it was completely buried for brumation.



> In the particular case of the sulcata, they live in burrows that are normally 2 - 8 meters deep. There are no night drops there. All the studies on ground temperatures show variations in daily temperatures become almost negligible at 0.25 m and below.



Would you mind linking me to a study by an actual researcher that has measured sulcata burrow temperatures and showed zero delta between diurnal apex and nocturnal nadir with statistically significant data sampling? I assume, for your position, that you would use that kind of data. Were the studies you are referencing based on probes inserted into the ground and allowed to equilibrate while buried with substrate making contact on all sides or in an otherwise enclosed space (to know the ground temperatures since you mentioned ground temperatures)? Or were the studies done in open-air sulcata burrows? My sulcatas do not bury themselves in the ground material when they retire to their burrows excavated from the ground material, so a buried probe lacks equivalence to an unburied sulcata and that is only in the context of the burrow.

When my sulcatas reside in burrows, they do not reside within them for 24 hours per day. If mine only lived in their burrows and never emerged for active periods, I would assume there was something wrong with them. When they are out and active, their burrow temperature is not the daily high temperature that the animals experience. My burrows are around two feet wide and air flows into and out of them. There is even a low howl like a seashell when the wind really picks up before or during storms. That the air is warmer in the day and cooler in the night is sped up some when wind is higher. Like a cave, the temperatures are muted, but have fluctuations. It is a tube. Not a capsule. My sulcata burrows experience daily highs and lows on a more narrow range of temperatures than the surface highs and lows, but my sulcata tortoises themselves are exposed outside of the burrow to highs much higher than the lows they are exposed to within the burrow at the nighttime low. But again, my sulcatas do not sit in their burrows for 24 hours per day, so I would not be one to use the burrow temperature range to extrapolate to the animal's temperature range. Nor would I use data from a buried probe to speak for a burrow experiencing air exchange because I would not want to come across as intellectually dishonest on the matter. The burrow temps have a delta that is greater than zero. The animals are exposed to a delta that is much greater still compared to their burrows. I am not breeding and raising burrows. I am breeding and raising sulcatas.



> To suppory my point, I will show just one of the dozens of charts I have on actual data for daily temperature values at depth. This is from a study done on the Island of Cyprus. It looks at one day that went from an air temperature of a low of 14°C (57°F) to a high of 32.5°C (90°F). So a mild day in the terms of our sulcatas but a temperature swing of comparable value. At 4" deep the temperature pretty much followed the air temperature with a lag of a few hours. That is in the open, unshaded soil. Not under a bush or any cover. However, even there, at 0.25 m (10") deep, the temperature only varied over the whole day from 22°C (71.5°F) to a high of 23.5°C (74.3°F) At a depth of just 1 meter, the variation over the course of the day is well under 1°C



Does this study's methodology have the probe placement performed in a sulcata burrow? Or is it a buried probe? If it is a buried probe and the species to be discussed are not buried beneath substrate to that depth, how does it support your point? Speaking of Cyprus (and Greece; I have been to both), when I have been there and observed the multiple species of tortoises _in situ_, their shells were rather warm to the touch in the daytime while active and somewhat cool to the touch at night while tucked into underbrush. Some with condensate on their shells during the early mornings at daybreak. Even going by my hand, that does not represent a delta of zero. These were primarily summertime visits. Spring and autumn seasonal variations combined with basking behaviors could make for an even larger delta for the animal's temperature within a day. In Greece, this involved a variety of terrains. Mountains. Valleys. Agriculturally developed areas. Undeveloped chaparral-like scrublands. Pine forests. Deciduous forests with springs or rivers (both seasonal and persistent). Three species in the Testudo genus in aggregate when dealing with exeriences combined from both countries.



> And the temperature at depth always stays within a few degrees of the daily average temperature.



With what probe placement methodology? Buried or with access to direct air exchange? If with access to direct air exchange, over what dimensions?



> So in their wild habitat, overnight low average never dips below 72°F throughout the year, and the daily average temperature (which ground temps follow) never dips below 85°F all year.
> 
> From this I can conclude pretty reasonably that retreating to a burrow, a wild sulcata never experiences a nightly temperature drop, and never endures temperatures below 80°F in their native range.



Even if you are talking about buried (substrate-encased) probes (apples) and not sulcata burrows (oranges) with air exchange or the actual sulcata tortoises (pears?) themselves, that is not the full range of exposures the animal experiences within its full day. You are taking data twice removed and making a conclusion based on measurements that were not taken of the very thing you are concluding on. A buried probe is not a burrow space. A burrow space is not a tortoise. A tortoise at night in a burrow is not the same temperature as it is during the day outside of that burrow. If I buried a tortoise completely at a particular depth to replicate a probe reading, that in no way represents what the tortoise would experience without me doing so.

And that is only speaking to sulcata tortoises since you decided to focus on that species. Other species experience a night drop as well. Their lowest resting temperatures at night are not the same as their highest active temperatures during the day unless you want to somehow reasonably conclude otherwise with measurements taken of the tortoises themselves. That delta or difference is the night drop. A leopard tortoise under the cover of brush and grass during the lowest temperature of a night is experiencing a night drop relative to if it stayed in that position while in the shade of the same brush and grass during the highest temperature of that day (which is still not the highest temperature it experiences while active during the day with direct exposure to sunlight). When a South African pardalis is observed having frost on its shell before dawn breaks, that is probably at a lower temperature than what the animal experiences at noon on the same day. That, too, is a night drop. When I have found redfoot and yellow foot tortoises during the day and then again at night, the temperatures were not the same at the level of the tortoises at those different times of day. Also a night drop.

As before.



> Nighttime temperature lows/drops are a natural thing in any wild environment and with greater or lesser fluctuations at different points in a year for the same geographic area.



At least for tortoises not brumating. Not talking about buried probes that do not represent active tortoises in a day/night cycle.


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## Anyfoot (Dec 12, 2017)

Baoh said:


> Well, there were all of the times I visited areas where I have found a number of species _in situ_ and where I found them during the day was of a temperature higher than where I found them at night. I have found tortoises in Europe, Central/South America, and Asia. The US, too, if we count Gopherus in this. I have yet to visit a place where the nighttime temperature of the tortoise at an activity nadir was equal to its daytime temperature at its activity apex unless it was completely buried for brumation.
> 
> 
> 
> ...


Would all the information of this post apply to a 4 month old tortoise that is hidden away most part(day and night)or are we saying a 4 month old is also active during the hotter day sun then retreats to cooler safety at night to give a night time low?

If a tortoise was hidden in the under growth where the temperatures are more stable throughout a 24hr period but above this micro climate the air exchange temperature varied through the 24 hr period, how would this effect dew in the microclimate where the tortoise hides?


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## Baoh (Dec 13, 2017)

Anyfoot said:


> Would all the information of this post apply to a 4 month old tortoise that is hidden away most part(day and night)or are we saying a 4 month old is also active during the hotter day sun then retreats to cooler safety at night to give a night time low?
> 
> If a tortoise was hidden in the under growth where the temperatures are more stable throughout a 24hr period but above this micro climate the air exchange temperature varied through the 24 hr period, how would this effect dew in the microclimate where the tortoise hides?



It may be a mix of both. A smaller tortoise will retreat earlier in general and tends to stay under cover more, although I have found bolder hatchlings out during hotter and brighter periods, too. I think there are multiple survival strategies at play with that. Staying hidden leads to reduced frequency of predation and desiccation (strategy one). Venturing out leads to greater food consumption and a higher metabolic rate to spur faster growth (strategy two). Strategy one's main benefit is improved survival rate. Strategy two probably has two benefits. A) Reduced time to a larger size reduces the number of predators that can make a meal out of you. B) Reduced time to a larger size increases your ability to outcompete "hiding" babies if there is a goal of spreading genetic material. Strategy 1 is to reach the finish line more reliably. Strategy 2B is to cross the finish line before others and direct the flow of the subsequent generations. Cosmetic benefits are probably a side effect. You could also argue a 1B exists in a time of relative famine where staying tucked in, eating less, and growing slower leads to survival where a bolder baby is burning energy. Hard to say. I sometimes wonder if there is a health or longevity benefit that has evolved from being subjected to a night drop. It might trigger an endocrine cascade that is beneficial, for example, that we do not know of. Kind of like how female fertility is variable with size and age. Size being primary. Age has some secondary benefit from what I observe. If I get a female carbonaria to large adult size in three years, she may not start to produce mature follicles until the fifth year while others in her situation do start at three. Meanwhile, I might have a female take seven years to eke out growth to a bare minimum reproductive size and she may then immediately produce upon reaching that minimum size. In the first case, there is size outpacing seasoning. In the second case, there is seasoning occurring in pace with size. I do not know why some females in the first case go right away while others have to season more. Just like I do not know if some benefit to symbiotic microorganisms might occur during the night drop. Or if there are bodily/cellular enzymes whose optima are set better for the lower temperature of the night for some function they serve during that portion of the day. I cannot say if any of these have any relation to a night drop, but these hypothetical examples are possibilities that fall under what I mean when I say we do not know what we do not know. For some of my projects with keystone animals, I move them forward swiftly. In the context of a concept like the Hayflick Limit, I may be spending the "bank" of cellular division earlier to get to a size milestone faster. Maybe and maybe not, but few things come without trade-offs. I suspect I am sacrificing the years of life that would have been spent growing out that animal to a given size. Say I get a female to ten inches in three years and her identical twin to ten inches in ten years and they have a lifespan of something like seventy years (for the sake of argument; these numbers are pulled out of the cloaca and are only meant to be for the concept discussion). It would not blow my mind to discover that supergrown female 1 lives for 63ish years and her more casually grown sister lives for 70ish years. With the way reptiles grow and live, this may not be the case, but I am also not too arrogant to state it will not be the case. A night drop, in this scenario, might stretch out the years. Unknown unknowns. Will this alter my plan for my more swiftly grown keystone animals? No, but I accept it is a possibility without hesitation rather than try to make myself feel better about it. I do not want to cherrypick this and that to start inductively feeding a narrative I want to support (this is too common).

A dew point should be easier to achieve in a cooler area of undergrowth. That means condensate more easily forms on the surface of the shell at the lower temperature and the condensate can then directly hydrate (and therefore lower tension of) the keratin. That flexible keratin will then not place as much tension on the underlying bone at acute angles and the force that is present is more diffuse. The bone should then grow in a more planar fashion and pyramiding should be reduced or minimized. The growth during periods of relaxation and "tightening" (as well as starts and stops) will result in annuli. More growth per relaxed phase should have wider annuli of fewer number. More relaxation/tightening cycles in a span of time should result in greater numbers of annuli of smaller widths. Fewer cycles with less extensive growth per cycle would mean narrower annuli, but at lower accumulation rate. Harder starts and stops, from what I see, lead to deeper grooves between annuli and this seems exacerbated if the beginning of the new growth phase lines up with the tightened portion (where keratin tension is high and that groove occurs from a more acute angle of pull).


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## Anyfoot (Dec 13, 2017)

@Baoh. 
Can you shed any light on when tortoises actually grow. I was reading something a while back about bone growth. One of the things I read was that mammals grow when at rest (sleeping) and not during active times. So basically the energy at rest is used to grow and energy at active times is used for the actual activity. Whether this is true or not I'm not sure, I struggle to trust anything I read on the open Internet 
If it is true would that also apply to ectotherm animals providing they were above a certain temperature. 
So for example, a baby tortoise is hidden in the dense moist foliage with its carapace moist and relaxed whilst asleep and is growing (growing in moist conditions). 
During some parts of the day it's active out in the sun with the carapace dry and tight but it's not growing because the energy is expended into activities not growth. 
If there is any possibility of that being correct then basically a tort sleeping whilst dry would grow and pyramid. So sleeping in the sun or under a basking light or in bone dry foliage would all contribute to pyramiding. This would also answer why babies may venture into the suns heat and not pyramid. 
It's all relivent to night time lows to, because we need the low to create dew in the wild is what I'm thinking.


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## Baoh (Dec 13, 2017)

Anyfoot said:


> @Baoh.
> Can you shed any light on when tortoises actually grow. I was reading something a while back about bone growth. One of the things I read was that mammals grow when at rest (sleeping) and not during active times. So basically the energy at rest is used to grow and energy at active times is used for the actual activity. Whether this is true or not I'm not sure, I struggle to trust anything I read on the open Internet
> If it is true would that also apply to ectotherm animals providing they were above a certain temperature.
> So for example, a baby tortoise is hidden in the dense moist foliage with its carapace moist and relaxed whilst asleep and is growing (growing in moist conditions).
> ...



They grow both while awake and asleep. So do humans, but that is a little different since human anabolism is not dependent on our immediate external environment's temperature (within reason). There is a nighttime growth hormone secretory pulse in mammals, but that is not a temperature-driven phenomenon in humans. Growth will be faster at rest than while active simply due to the allocation of Calories being less divided. With ectotherms, anabolism will be higher while warmer. Sleeping and warmer will grow faster than sleeping and cooler. Having a cooler nighttime period should lead to smoother growth to a degree compared to a warmer nighttime period *_if_* no compensatory keratin flexibility is induced while warmer. Many keepers keep tortoises warmer than they would experience naturally at night, but the provision of a humidity boost and the more supple state of the keratin compensates for that (mostly). That really only lets us observe the pyramiding part. If there are some unknown compromises (or benefits...or nothing at all), I am not sure anyone has studied them.

I think the warm-versus-cool nighttime sleeping condition and its effect on pyramiding (without compensation) has been studied.

Something in relation to growth and temperature was examined in developing chelonian embryos before. A low incubation temperature causes a greater difficulty in both maintaining the tissues and expanding them, whereas the warmer temperatures allow easier maintenance and growth. This assume adequate Calories (yolk for embryos). One thing to consider that feeds back into something I mentioned is endocrine pulses and cascades. I have not looked into chelonian growth hormone pulses if that information is even available. I remember the peptide sequence for sea turtles being worked out, but little else last time I looked.

As for babies, they do get up a bit after morning warmth sets in. In Testudo in the summer, that goes until maybe 10-11am (usually no longer and it seems to cut off by 10am more often than not with the little ones). There is then the second period of activity as the Sun is lower in the sky again until they retire by dusk for the cooler night and the dew it brings (plus they tend to dig in slightly in rootstock and other little sheltered areas). I have found exceptional babies and small juveniles walking along in the blazing sunlight out in the open at 1-3pm (asking for death, little fellows), but this is not the norm.


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## Markw84 (Dec 13, 2017)

@Baoh 

The discussion is: if I provide a stable ambient temperature of 80° in captivity for my tortoise, and certainly provide a daytime basking area of about 95°-100°, would the nighttime ambient be better if we allowed it to drop below 80°?

It is exactly the statements that "when I see tortoises in the wild, they are certainly warmer in the daytime than they are at night" and the reliance on weather data of air temperatures in their natural range that I believe is misleading. From that we ASSUME things as wrong as "sulcatas are an arid species, coming from an arid habitat and should be kept dry and not humid in captivity". Anyone observing a sulcata in the wild would certainly agree with that. But where we are observing them in the wild, is not where they live the vast majority of their lives.

Knowing the temperature of the extensive thermal mass surrounding an uninsulated, narrow tunnel in the ground is far more telling than air temperatures or what we observe when we find them above ground -when they spend about 95% of their time in their borrows. That is what they seek out to maintain their lives in an environment they have found ways to endure. I know of no one who has spent more time studying sulcatas in their natural range than Bernard Devaux and Thomas Diagne. Thomas's comments to @Tom in visiting a sulcata enclosure in Arizona, was that he was amazed at how differently sulcatas act here as opposed to in the wild. He couldn't believe how much time the tortoises were out! In Africa he says they rarely are seen. To find them you look for burrows. They spend at least 95 of their time in those burrows, rarely coming out. It seems that indeed they use those burrows to not only find more humidity, but to keep their bodies at a stable temperature as much as possible. In their native range, for the reasons I laid out above, I believe they have found that stable temp of around 80° in that burrow. Not night drop, no daytime rise. The use the sun and daytime "outside" temperatures to heat their body to a more active level for foraging and seeking a mate. But always retreat to that stable climate of their burrow as temps climb to 115° + or dip to the low 70°'s in a cold night. They do not endure or experience a night drop. In our areas, with a much more temperate climate, the tortoise does not have to spend as much time hiding from conditions that will overheat it. So staying at a comfortable temperature does not require a burrow. Here, it is the night that is more of a problem and all our tortoises are very good about finding their night boxes as temperatures drop. Totally different than in the wild where it is the heat that is the main threat. Here, where we are keeping them, they have to learn how to deal with *cool* temperatures. Our tortoises become so active throughout the day as it is no longer a problem for them to keep their bodies at their preferred temperatures when the sun is out and it is anywhere from 70°-100°. Just move in the sun, or move to the shade. 80°-85° body temp - no problem. But when it cloudy and 60°, or at night and 60° suddenly our tortoise act like a wild sulcata, and retreat to the burrow seeking a way to maintain that body temp. How many people endlessly ask about how their sulcata slows down in winter and barely comes out, eats far less. But heat their night box, their "burrow" to 80° and see how they act. Much more active, and needing to seek out the burrow much less until their thermal mass is overcome by the ambient air. So are they seeking out, or "do better" with a night drop? I see no evidence of that anywhere.

You discount the value of knowing ground temperatures in trying to figure out what our tortoises really need or 'prefer'. Yet I find value in this information. Looking at the chart I posted above, you can see according to that data it is about 10" deep where temperature stabilizes and becomes almost totally resistant to daily swings. I don't believe it is coincidental that the sulcata is the only tortoise that digs a body pit prior to digging the egg chamber. They are in this way getting the top of the nest chamber, and the topmost eggs, below 10". According to my conclusions above, at that level, the nest chamber is now able to maintain a steady 82°-90° throughout the times of year eggs would be in the ground. Using the same data, we can see that if they dug nests any shallower, the eggs would cook and die. We see going deeper, those temperatures are maintained. Would I rather see lots of great data from someone sticking a data logger in actual nests and recording and then publishing the results. YES! But we don't have that. But understanding basic thermodynamics, heat transferring processes for soil and actual ground temperatures - and then combining that with what we have found is actually working in incubators - we can draw some pretty convincing conclusions.

I would love to see some actual data from a data logger in a burrow. But would it have the accuracy of the data that has been developed by companies investing 100's of million of dollars in developing the most efficient heating and cooling system for adverse climate areas around the world? What tortoise field researcher has those types of resources to invest in state of the art equipment and monitoring? You would also have to account for the movement of the tortoise and the fact that the tortoise is actually blocking the burrow with it's body where only 20% or so is even exposed to the "open" side of the tunnel. But I would even discount that as the amount of thermal exchange from any air that could make its way into a single-opening tunnel is negligible. Also, the way a tortoise constantly scratches at the soil as it enters its burrow (or night box) and settles in - exposing fresh, and more moist, soil. Those actions would produce different readings than a data logger laying in a burrow. Perhaps someone can attach a data logger just under the rear margin of the carapace?? That would be interesting!!!

But we do not have that data. We have been keeping sulcatas in numbers for about 3 decades now and still only recite weather station statistics, and anecdotal stories of how we felt and how it seemed when we found a tortoise that we happened to catch in the rare times it was out and about. We have done a lot now to see the results of husbandry practices. They grow faster, smoother, and are much more active when kept humid. That has caused us to rethink the "dry" conditions that exist in the wild and indeed find evidence they find ways to avoid dry and stay much more humid in the wild than any weather data suggests. (or stories of how hot and dry it was when someone found one in the wild!) We find the same is true when we keep them at 80° with basking area provided. We see them slow down and not eat as well, and reproduction is less as temperatures drop below that level. So now I look and see that all the data supports that indeed ground temperatures fall exactly within those ranges we find works in captivity best. Not weather station data, but ground temperatures. And that same data, combined with the way the tortoises actually lives is telling us there is no night drop below 80°.

I focused on sulcatas because it becomes a futile case of varying scenarios to shift from species to species while trying to make the point. But if we do see that the conclusions about this do apply, then it is a better set of values than weather station data alone - to then apply to the different species. We can look at average ground temperature in their native ranges. We can use that to mitigate the weather station data. We would need to apply if they burrow, or make pallets, or hide under leaf litter, or logs, or in crevices - those would have varying effects on how much the thermal mass of the earth overcomes the heating power of the air that is able to get to the hide. We can also look at burmating species and average air temperature data - apply that to known ground temperature constants and see when and at what temperature brumation is actually maintained.

My main contention - tortoises have developed ways to stay much warmer than any weather station data suggest, or the evidence we see when we catch them out and about may suggest. And when that information alone is used to justify why it's advisable to give your tortoise a night drop - I respectfully disagree!


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## Baoh (Dec 13, 2017)

> The discussion is: if I provide a stable ambient temperature of 80° in captivity for my tortoise, and certainly provide a daytime basking area of about 95°-100°, would the nighttime ambient be better if we allowed it to drop below 80°?



No, the original post is as follows.



> One aspect of tortoising I've neglected to look at is lower temperatures at night.
> I just don't bother with a drop in temps with my redfoots or homeana. Maybe this is an area I need to look at.
> For my radiated I've got temps dropping at night.
> For the last few weeks I've been watching the weather in Madagascar(Toliara). Basically at this time of year it's around 86f/91f and 60/70% in the day and 75/80f and 80/90% at night.
> ...



I have addressed the elements of the original post. It leads the discussion and then it can sprout tangents during the course of responses. You are now trying to reframe that within goal posts of your own choosing.



> It is exactly the statements that "when I see tortoises in the wild, they are certainly warmer in the daytime than they are at night" and the reliance on weather data of air temperatures in their natural range that I believe is misleading. From that we ASSUME things as wrong as "sulcatas are an arid species, coming from an arid habitat and should be kept dry and not humid in captivity". Anyone observing a sulcata in the wild would certainly agree with that. But where we are observing them in the wild, is not where they live the vast majority of their lives.



I did not assume any of that. Nor did I rely on weather data of air temperature readings from weather stations in their natural range.

As for being misleading, you seem to be focused on using data from ground temperatures that do not represent burrow temperatures (caves "breathe" and so do burrows) to then represent burrow temperatures and by proxy represent the animals' temperatures. It is like trying to speak to precipitation exposure in the burrow based on rainfall on the surface. If I did that, I would be intellectually dishonest. If I used values from a probe buried in the ground to speak for a burrow as fact and then tried to say that the buried probe's environmental condition is what animals not buried are experiencing, I would be intellectually dishonest.



> So are they seeking out, or "do better" with a night drop?



Not sure if anyone has said the tortoises are expressly seeking out a night drop for the sake of a night drop itself. Rather, they are exposed to one incidentally through a combination of hiding behavior and nighttime temperature cycles (which someone does not want to believe exist) and it is possible that this could serve one or more benefits to the biology of the tortoises. No overly hard conclusions on specious data (which is exactly what using ground data here is doing; this tends to be looked upon poorly by any ethically-minded scientist). No rushing to close a case that is incomplete.



> You discount the value of knowing ground temperatures in trying to figure out what our tortoises really need or 'prefer'. Yet I find value in this information. Looking at the chart I posted above, you can see according to that data it is about 10" deep where temperature stabilizes and becomes almost totally resistant to daily swings. I don't believe it is coincidental that the sulcata is the only tortoise that digs a body pit prior to digging the egg chamber. They are in this way getting the top of the nest chamber, and the topmost eggs, below 10". According to my conclusions above, at that level, the nest chamber is now able to maintain a steady 82°-90° throughout the times of year eggs would be in the ground. Using the same data, we can see that if they dug nests any shallower, the eggs would cook and die. We see going deeper, those temperatures are maintained. Would I rather see lots of great data from someone sticking a data logger in actual nests and recording and then publishing the results. YES! But we don't have that. But understanding basic thermodynamics, heat transferring processes for soil and actual ground temperatures - and then combining that with what we have found is actually working in incubators - we can draw some pretty convincing conclusions.



Moving goal posts again, I see. Buried (encapsulated by earth) data are useful for a buried application. There is better representation of a nest by a probe buried at nest depth. That ground temperature data would indeed be useful for examining that topic (that is not in dispute here). We were not talking about that and I am sure you realize it, however.



> I would love to see some actual data from a data logger in a burrow.



So would I since that is central to some elements of your positioning.



> But we do not have that data.



Then it is intellectually dishonest to hand-waivingly choose and accept an inaccurate substitute that does not serve as the proxy for what is lacking. If I tried to use core body temperature to speak to phalange temperature in a weather exposure condition, I would be quite remiss.



> I focused on sulcatas because it becomes a futile case of varying scenarios to shift from species to species while trying to make the point.



The totality of tortoise species have been included in the discussion, breaking out particular examples, but not hinging on any single one. You focused on using twice-removed data measuring something else to speak directly for something that was not measured. At least if it had been burrow temperature versus animal temperature, there could be some kind of trending relationship established, but that is not what was done.



> My main contention - tortoises have developed ways to stay much warmer than any weather station data suggest, or the evidence we see when we catch them out and about may suggest. And when that information alone is used to justify why it's advisable to give your tortoise a night drop - I respectfully disagree!



Yeah, but I do not care if you disagree with me or if you agree with me and want to give me endless hugs and back rubs. I do care that you misrepresent things on purpose with data of one type because the data that matter are not actually available to you. Makes me distrust other things you might say. Like claiming chelonians use the bloodstream as a medium for glycogen storage (when glycogen is not stored in the bloodstream; it is kept in tissues) or claiming it is a fact that tortoises do not store fat as an energy reserve (as an absolute assertion) when they do have distributed peripheral adipose depots that function quasi-similarly to human subcutaneous WAT (although not nearly so extreme; this has been studied in chelonians by Pond and Mattacks).


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## Markw84 (Dec 13, 2017)

Misrepresent things on purpose??


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## Markw84 (Dec 13, 2017)

Baoh said:


> As for being misleading, you seem to be focused on using data from ground temperatures that do not represent burrow temperatures (caves "breathe" and so do burrows) to then represent burrow temperatures and by proxy represent the animals' temperatures. It is like trying to speak to precipitation exposure in the burrow based on rainfall on the surface. If I did that, I would be intellectually dishonest. If I used values from a probe buried in the ground to speak for a burrow as fact and then tried to say that the buried probe's environmental condition is what animals not buried are experiencing, I would be intellectually dishonest.



Caves "breathe" if there are more than one opening to the surface. A burrow is more like a mine. In a mine, you need forced ventilation in order for anyone to even work there. But even in caves, they are well know for their extremely stable air temperatures. Once you get a few cave-opening-diameters into a cave, the temperature will stay year-round with a degree or so of the average yearly temperature of the area in which the cave is located. Not only no daily fluctuation at all, but no annual fluctuation at all! Texas caves are know for being a constant 70°. Minnesota caves, a constant 50° or a bit colder further north in the state. In studying passive heating and cooling systems and the concepts a lot of design is based upon, it is the thermal inertia of the ground that totally overcomes the minute thermal inertia of air that is used to help these systems be so efficient. The value of a probe buried in the earth is DIRECTLY relative to the temperature in a burrow. Are you implying the thermal inertia, and thermal mass of the small amount of air that is in a burrow, and has very little exchange, can overcome the thermal inertia of the uninsulated bare earth walls, floor and ceiling of a burrow? I cannot in a wine cellar. It cannot in a buried pipe used to pump cool air for a very basic cooling/heating system (active air flow). It cannot in a mine or in a cave. But it can in a small burrow with no active air flow?

Intellectually dishonest???


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## Markw84 (Dec 13, 2017)

Baoh said:


> Yeah, but I do not care if you disagree with me or if you agree with me and want to give me endless hugs and back rubs. I do care that you misrepresent things on purpose with data of one type because the data that matter are not actually available to you. Makes me distrust other things you might say. Like claiming chelonians use the bloodstream as a medium for glycogen storage (when glycogen is not stored in the bloodstream; it is kept in tissues) or claiming it is a fact that tortoises do not store fat as an energy reserve (as an absolute assertion) when they do have distributed peripheral adipose depots that function quasi-similarly to human subcutaneous WAT (although not nearly so extreme; this has been studied in chelonians by Pond and Mattacks).



Let's see who misrepresents on purpose. Here's what I actually posted. I found it in the thread "Hibernation Help" post #10 Nov 19, 2017

"A brumating reptile has very little fat stores and instead uses increases glycogen levels as their energy source during brumation. They do not "store fat" for the winter as a mammal does. They add increased levels of glycogen that is stored in the bloodstream and cells throughout the body. (This also actually serves as a sort of antifreeze as well. The freezing point of the tissue is actually lowered which protects many aquatic species that hibernate where they can sometimes be exposed to temperatures slightly below freezing!!) So they do not lose any appreciable weight from body mass. Any weight loss is an indication of water / hydration loss. A brumating turtle or tortoise should normally have practically NO weight loss. If there is - it is an indication of them becoming dehydrated."

I did say "bloodstream and cells throughout the body." Are you saying they do not carry glycogen/glucose in the blood? The glycogen is allowing the blood and cells to have a lower freezing point as shown in studies on C. picta and C. serpentia plus providing the little energy reserves needed by functioning organs. It also allow for existence in an anoxic environment many aquatic chelonians can survive during brumation.

I did say "do not 'store fat' for the winter like a mammal does." Are you saying chelonians do store fat for the winter like a mammal does?? That they use fat stores to provide the energy needed for brumation as opposed to glycogen stores?? You cite reference to Pond and Mattacks. I am aware of quite a few article by them exploring the various places adipose tissue is stored in the body and looking at how that can be an indicator of health problems. I have never seen any study by them of chelonians. Mostly human related illness explorations. I've seen them reference many animals as examples of the very common way adipose tissue is located beneath the skin and how universal that is, even when fat is not stored as a primary energy reserve. Is that what you are referring to??

Who is misrepresenting on purpose??


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## Ernie Johnson (Dec 14, 2017)

I'll chime in with regard to tropical forest torts - Redfoot's. I'm in the nighttime temp drop has no effect on them camp and here's why.

If you look at Guyana (where my breeding pairs parents are from originally) it's a fairly accurate representation of any around the equator tropical country with a high percentage of tropical forest from a temperature range perspective.

In Georgetown (right on the coast) you can see how little variation there is from night to day all year long. Obviously this is not a "hot spot" for Redfoot's or Yellowfoot's, I provide it to show that when you go to another part of the country (southwest area) with open Savannah's -Lethem - there is still no variation in temp. 

If you went smack dab into the think forest areas you'd see even less of a temperature range.







This is obviously over simplifying things, however I add this to provide evidence for tropical species like Redfoot's and Yellowfoot's (both indigenous to Guyana) the night time temp drop theory doesn't apply because it simply doesn't happen.

So, what "may" apply to tortoises from arid environments can't be seen as a universal across the entire range of species.


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## Anyfoot (Dec 14, 2017)

@Baoh. Off topic. Where did you see tortoises wild in Cyprus? I didn't think there was any native torts in Cyprus. We've only been to the south side of the island.


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## Markw84 (Dec 14, 2017)

e


Anyfoot said:


> @Baoh. Off topic. Where did you see tortoises wild in Cyprus? I didn't think there was any native torts in Cyprus. We've only been to the south side of the island.


I don't think he referenced finding tortoises on Cyprus. I referenced Cyprus only as I had very exact data on hand for ground temps at very precise and shallow depths done for a passive cooling/heating system there.


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## Anyfoot (Dec 14, 2017)

@Markw84 

It's the post after you referenced Cyprus. 
If it's a mistake I'm not bothered, but Cyprus is a preferred holiday destination for Dawn, it will also be mine if torts are on the island  

Baoh said. "Speaking of Cyprus (and Greece; I have been to both), when I have been there and observed the multiple species of tortoises _in situ_, their shells were rather warm to the touch in the daytime while active and somewhat cool to the touch at night while tucked into underbrush".


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## mark1 (Dec 14, 2017)

to use body fat I believe they need to have a body temp high enough to metabolize it , personally I believe that happens in the beginning and end of hibernation(brumation) or in the winter in unusually warm spells when they are active but not feeding .......... I have to think glycogen in the bloodstream is just a misnomer , in that you mean glucose , which as much as most tend to see them as the same , yet they are not , but one is responsible for the other........... when glucose levels rises in the blood in a hibernating reptile , it's been shown glycogen levels in the liver lowers .....





Baoh said:


> As for lows in terms of tolerance, this will depend on a bunch of things. Species. Subspecies or locality. History of exposures allowed (huge, huge factor). There are few good reasons to explore an animal's limits of tolerance. That is more for knowledge-gathering than anything of benefit to the animal, although it is valuable to other animals in future applications or considerations. However, the rise of over-coddled animals is something interesting. Animals which experience an accidental 50-60-degree night and suddenly are weakened and experience rapid illness are a shame to see. Animals which are allowed to experience gradual exposures tend not to react like that. There is a tempering process that can be achieved if done with some intelligence (or luck for some that do not plan it, but that does not necessarily end well often). Hardened animals are more safe when an unforeseen event occurs. You have no express need to explore this, but there is a benefit. It is also cool to observe it. An excellent example that has been showcased here is Len's male sulcata (Walker). I have countless personal examples. The principles apply to any species of tortoise, although the extent varies with species and individual. It is not all-or-nothing.



this is a great observation , I've done both , out of ignorance with redfoot tortoises , and on purpose with P.Manni ....... the tortoises I just kept in my parents backyard all summer because it seemed where they should be ....... when I first got manni , I kept them in a room with a humidifier at 80degrees , 90-100 degree basking area , i'd put them outside in northeast ohio in july and august , 30yrs later , I put them out in june and bring them in in October , just provide a spot for them to get hot , same in the house ....... finding these tolerances served a purpose , they are much better off being kept outside as long as possible ..... they lay more eggs now than ever before , I think that's an indication of better husbandry ,imo reptiles need the sun ..........




Ernie Johnson said:


> I'll chime in with regard to tropical forest torts - Redfoot's. I'm in the nighttime temp drop has no effect on them camp and here's why.
> 
> If you look at Guyana (where my breeding pairs parents are from originally) it's a fairly accurate representation of any around the equator tropical country with a high percentage of tropical forest from a temperature range perspective.
> 
> ...



I don't believe air temperature is what reptiles use to thermoregulate ............ I think you'll find Georgetown temps are moderated by sitting next to a massive constant 80 degree heat sink ....... if you move 40 miles southwest you'll see lows in jan-feb in the 60's ......... regardless 90degrees and sun is way hotter for a reptile than 75 and dark , they will not thrive at 75 and dark , they can do just fine at 75 and sunny ........ I would think galapogas tortoises on the island even see nighttime cooling ........have no idea of the benefits , but I have to think the fact is a no brainer .......


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## Anyfoot (Dec 15, 2017)

In my radiated 6x2x2ft vivarium I have 6" depth of substrate. For their hide I have an area that is 2x1ft with only 2" depth that slopes up at either side to the 6" depth substrate. On the 2" depth area I have 4" depth of foliage for bedding. This is where they sleep. I am using a proportional day/night thermostat. My max daytime air temp is 91f and my max nighttime low air temp is 81f. This is measured about 1" above the substrate right next to the bedding. 
I have a probe inside the bedding where the torts sleep. Max daytime temp is 80f and max nightime low is 78f inside the bedding. 
So in my enclosure my air temp variation is 10f at the measured point and my bedding temperature varies by 2f at 3" deep where the torts sleep. My night time temp kicks in at 9pm for 10hrs.


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## Anyfoot (Dec 16, 2017)

One of the areas of our methods for trying to grow a smooth tortoise that I can get my head around is soaking. It definitely makes a difference and is one method to grow a smooth tortoise. Even though I do soak my babies I've often thought how and where does this artificial method fit in with natures way of combating the carapace hydration problem so the keratin is not tight. We've talked about hatching in babies hatching in wet season but wet season doesn't last a whole yr and our babies need to be soaked for longer that an wet season lasts. Or there is they soak in puddles thought, but surely every single baby out there of every single species doesn't happen to have access to puddles. Many Greeks live in pine forests on hill sides. Puddles and hillsides don't mix. 

So to get the equivalent to soaking our tortoises in nature must be dew. At night where ever they live in the world the night time air cools down and humidity increases to the point of dew (100% RH). 
This does not mean the the microclimates that babies live in have vast temp differences from day and night. But it does mean the air above these microclimates falls at night causing the dew point.
Even in South America in Bahia where it is a dryer climate than let's say Suriname it only 40% in the day and 85f, it increases to 90% and down to 70f at night. In the microclimate at ground level it will be 100%(dew point) 
Or in Madagascar when it's 60% and 90f in the day then 85% and 75f at night the microclimates we are interested in will be 100%. 
These micro climates will be relatively stable compared to the open climates that endure the full force of weather, wind, rain and sun. 

I have a friend who lives in Brazil, he is adamant that babies bask in the morning and says this is why only 2 or 3 survive out of 100s It's the risk they have to take but a predators buffet. He's on the task of getting me photos of this. So maybe the microclimates that have 100% RH for most part makes basking for an hour in the morning and in the evening not harsh enough to dry the carapace to the point of pyramiding. 
How's it all relevant to night time lows, if there is no highs and lows, there is no dew. This doesn't mean there has to be highs and lows in the microclimates but in the open climates above. 
Giant Galapagos do endure heat of the sun and obviously when the sun goes down so does the suns heat. But what about the baby Galapagos that are hidden away, they don't endure the day/night open climate like the adults have to endure. Do you think these baby Galapagos have 100% RH at night then bask for an hour in the morning or not? 

Below is an interesting link. 

http://biomet.ucdavis.edu/frostprotection/Measure Dewpoint/fp003.html


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## mark1 (Dec 16, 2017)

it appears to me , turtle and tortoise behavior is aimed at maintaining a stable body temperature , their biology is to deal with circumstances when they can't ........ as far as cooling for part of a day , they appear to have behaviors to minimize it as much as possible , if it was beneficial you'd see them trying to get colder than their preferred body temp , which I've never seen , but you will see them move out of a spot that's too hot or cold to maintain it ....... it's been shown that given the choice they do move to maintain a preferred body temp ....... I don't believe it's ever been shown they move to get below those preferred temps .............hibernation I would think is a different circumstance , obviously a survival behavior , it does appear to me it's benefit is that it does have a biological place in the life cycle of reptiles evolved to naturally hibernate ....... cooling at night naturally happens , and I'd think it also happens in your enclosure just by turning off the lights ........ when I kept redfoot tortoises they had no basking lamp , they were kept under fluorescent lights in an 80-85 degree room with a humidifier , kept outside for 3 months a year , I had not a clue about pyramiding , and those tortoises were barely pyramided , I looked for pics , couldn't find any , I actually think they were not pyramided at all , hard to remember as it was a long time ago, the elongateds I do remember seeing those pics , and they were not even a bit pyramided , I don't even remember seeing growth lines on them ....... I have to think the pyramiding I see in some of these tortoises is a result of constant optimum body temp, they're constantly growing , and the drying effect of the lights and heat we use in the enclosures ....... I am a believer in the humidity theory and shell keratin..........

I would correct myself in that I believe I've seen the urge to hibernate override the urge to maintain a preferred body temp .


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## Anyfoot (Dec 16, 2017)

As usual I was in a rush and constantly being interrupted when I wrote the above post and didn't proof read. Re-done it. 


One of the areas of methods for trying to grow a smooth tortoise that I can not get my head around is soaking. It definitely makes a difference and is one method to grow a smooth tortoise. Even though I do soak my babies I've often thought how and where does this artificial method fit in with natures way of combating the carapace hydration problem so the keratin is not tight. We've talked about babies hatching in wet season but wet season doesn't last a whole yr and our babies need to be soaked for longer than just a wet season lasts for. 
There is they soak in puddles thought, but surely every single baby out there of every single species doesn't happen to have access to puddles. Many Greeks live in pine forests on hill sides. Puddles and hillsides don't mix. 

So to get the equivalent to soaking our tortoises in nature must be dew. At night where ever they live in the world the night time air cools down and humidity increases to the point of dew (100% RH). 
This does not mean the the microclimates that babies live in have vast temp differences from day and night. But it does mean the air temp above these microclimates falls at night causing the dew point.
Even in South America in Bahia where it is a dryer climate than let's say Suriname its only 40% in the day and 85f, it increases to 90% and down to 70f at night. In the microclimate at ground level it will be 100%(dew point). 
Or in Madagascar when it's 60% and 90f in the day then 85% and 75f at night the microclimates we are interested in will be 100%. 
These micro climates will be relatively stable compared to the open climates that endure the full force of weather, wind, rain and sun. 

I have a friend who lives in Brazil, he is adamant that baby redfoots bask in the morning and says this is why only 2 or 3 survive out of 100s. It's the risk they have to take but a predators buffet. He's on the task of getting me photos of this.
Maybe the microclimates that have 100% RH for most part makes basking for an hour in the morning and in the evening not harsh enough to dry the carapace to the point of pyramiding. 

How's it all relevant to night time lows, if there is no highs and lows, there is no dew. This doesn't mean there has to be highs and lows in the microclimates but in the open climates above to create dew that maintains the microclimates for smooth growth. 
Giant Galapagos do endure heat of the sun and obviously when the sun goes down so does the suns heat. But what about the baby Galapagos that are hidden away, they don't endure the day/night open climate like the adults have to endure. Do you think these baby Galapagos have 100% RH at night then bask for an hour in the morning or not? 

Below is an interesting link. 

http://biomet.ucdavis.edu/frostprotection/Measure Dewpoint/fp003.html


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