# Humidity and aridity



## GeoTerraTestudo (Feb 20, 2012)

A moist substrate is necessary for all terrestrial chelonians. Some of these species (like eastern box turtles, red- and yellowfoots, and hingebacks), are native to habitats with lots of precipitation, and need high levels of humidity in captivity as well.

However, some tortoises and box turtles come from arid or semi-arid environments where the ambient air humidity is rather low.

I have noticed that some people provide high humidity levels for tortoises like the sulcata and the Russian, or for western box turtles, even though these species come from grasslands where humidity is naturally low.

In my view, this is not necessary, adds effort and expense, and may even be harmful to these arid-adapted animals. Although they should have a moist substrate to burrow into, I don't think these species require elevated levels of ambient humidity. What do you think?

BTW - I would think the same applies to babies of arid or semi-arid species. Babies hide more than adults, so they might experience more humid conditions by remaining concealed under the substrate. However, when they go out to forage, they would be exposed to the same low humidity as adults. Why not let them?


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## Madkins007 (Feb 20, 2012)

I think that this discussion has an lot of surprising elements. Part of the issue is not so much trying to maintain a 'high' humidity habitat as it is just overcoming the drying effects of overhead lighting, low ambient humidity in most homes, foods that have lost lots of their moisture, etc.

So, PART of our humidity struggles is just trying to make things 'normal'.

Then, we need a better understanding of local natural humidity issues and how they affect the tortoises. Andy Highfield's research seems to show that Mediterranean tortoises just plain don't spend a lot of time in places with significantly raised humidity, period. We need a better understanding of how they remain so smooth and hydrated in such arid conditions.

Even many red-footed tortoises live in places where humidity is not all that high for chunks of the year- how does that work?

Another big question would be about the long-term effects of high humidity on various species. Does it bother the respiratory system or immune system? Does it make for weaker scutes as Andy Highfield wondered? Is it a concern or a non-issue?

I bet there are smarter ways to set up habitats so we can maintain a more 'normal' 40% humidity and offer good light, heat, air quality, etc. without having to soak the substrates, or blast them with light, etc. and without costing an arm and a leg.


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## EKLC (Feb 20, 2012)

When things are wet, there is much more food. I wonder if wild torts avoid pyramiding by doing most of their growing in the rainy seasons.


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## Madkins007 (Feb 20, 2012)

Diet and its relation to seasonal climate is, I think, one of the keys to making everything 'work'. I would love to see more research on this.

Most torts have a wet and a dry season. In the dry, they eat leaves, grasses, hays, etc. with low carbs, high calcium, low moisture, high fiber. They wander a lot (building up vitamin D) when temps allow and sleep when it is too warm. In the wet, they get fruits, flowers, bugs, etc.- lots of carbs and moisture. 

In captivity, they get one basic climate (two if we count in and out), and one basic diet- usually a pretty 'rich' one.


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## GeoTerraTestudo (Feb 20, 2012)

Madkins007 said:


> Diet and its relation to seasonal climate is, I think, one of the keys to making everything 'work'. I would love to see more research on this.
> 
> Most torts have a wet and a dry season. In the dry, they eat leaves, grasses, hays, etc. with low carbs, high calcium, low moisture, high fiber. They wander a lot (building up vitamin D) when temps allow and sleep when it is too warm. In the wet, they get fruits, flowers, bugs, etc.- lots of carbs and moisture.
> 
> In captivity, they get one basic climate (two if we count in and out), and one basic diet- usually a pretty 'rich' one.



Fascinating hypothesis, Mark. I think you may be onto something here.


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## Tom (Feb 20, 2012)

GeoTerraTestudo said:


> Why not let them?




Very simply... Because they pyramid.

Very little is know about the hatchlings of ANY species in the wild. Here are a few things I've recently learned that are relevant to this discussion.
1. Sulcatas hatch during the rainy season. Very hot, wet and humid. The few that have been seen by my tortoise researcher friend in Senegal, were all found in a marshy area.
2. While the area of the world where sulcatas come from can be classified as arid for a large part of the year, we are talking about surface conditions. According to my friend, wild sulcatas seldom come above ground outside of the rainy season.
3. Since we have very little idea what wild babies do, we are left with what we are able to observe and learn in our captive environments. Dry=pyramiding. Wet=smooth. Its just that simple.

In the original post you make a reference to babies and their needs vs. adults. I think this is HUGE. I do not advocate keeping adult sulcatas, leopards or russians with the wet routine. My adults all live outside where we have single digit humidity most of the year. They seem to be doing fine to me.


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## GeoTerraTestudo (Feb 20, 2012)

Tom said:


> Very simply... Because they pyramid.
> 
> Very little is know about the hatchlings of ANY species in the wild. Here are a few things I've recently learned that are relevant to this discussion.
> 1. Sulcatas hatch during the rainy season. Very hot, wet and humid. The few that have been seen by my tortoise researcher friend in Senegal, were all found in a marshy area.
> ...



Wow, very interesting. I think you may be right about the differences between the wet and dry seasons, and between the needs of juveniles and adults. Is this pattern pretty universal among tortoises and box turtles, or is it unique to sulcatas?


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## DanaLachney (Feb 20, 2012)

Well if you think about it you very seldom see Pyramiding in aquatic or semi aquatic turtles because they are wet correct? So common sense would tell you moist conditions for growing torts would work better than dry ones right?


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## Tccarolina (Feb 20, 2012)

Madkins007 said:


> Diet and its relation to seasonal climate is, I think, one of the keys to making everything 'work'. I would love to see more research on this.
> 
> Most torts have a wet and a dry season. In the dry, they eat leaves, grasses, hays, etc. with low carbs, high calcium, low moisture, high fiber. They wander a lot (building up vitamin D) when temps allow and sleep when it is too warm. In the wet, they get fruits, flowers, bugs, etc.- lots of carbs and moisture.



This is interesting, where is this research from? My meditereanean tortoises graze all day in our wet, moist spring on weeds and grasses. I live in a Meditereanean climate, and all our native fruits and berries are ripe in the fall and winter mostly. In the wet spring, it's a time of renewal, and there are only weeds and flowers available, of which they prefer the leaves, but will eat the flowers. It rains sporadically in Feb, March, April, and May, but the tortoises spend most of thier daytime alternating between baskingin the sun and hiding in the weedy cover.
While our spring humidity is lower in the direct sunlight, the lush weeds are quite humid, and they spend a lot of time in them. At night in the spring, humidity returns reaching 70 to 100 percent. Dew abounds in the mornings, and burns off by mid to late morning. So even though the humidity might be low in the sunlight at mid-day, that's only a small part of the story. All that time foraging, along with the humid nights, have to be factored in.

As mid-summer draws on, the weeds dry up and the tortoises are only active in the morning and late afternoon, where they make rather quick activity runs around the pen, before heading back to their hides.
IF I didn't continue to feed them, I think they would cease activity, and hunker down all summer. They will eat some dry leaves in the summer, but not much. I think that if they are no longer getting moisture with their food, they stop consuming.
Even into the fall, with milder temperatures, my greeks don't feed on the dry leaves, other than the occasional nibble. They bask somewhat, and eat green material if they find it, but they are consuming FAR less in the dry season they they do in the wet season.
I realize my pen is half a world away, and that I cannot totally mimic their natural environment, but what I'm observing in my wild-caught tortoises, in a naturalistic pen and similar climate, should be at least somewhat representative of their wild behavior.

Can you provide any articles you're basing this off of? I haven't heard of the low carb in the dry season, and high carb in the wet concept yet. I really like Andy Highfield's articles.

I am also curious about whether Andy Highfield every spent time in the early and mid-spring looking for tortoises. I can't imagine they were all trying to find dry locations during that time of year. Mine are out feeding already, as long as the sun is out for them to warm up first. 

Steve


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## Tom (Feb 20, 2012)

I really don't know as much about other species. Most of my study efforts have been towards the species I am most interested in. As far as I know, nobody knows a whole lot about wild babies of any tortoise or box turtle species. We know that whatever they are doing they are doing it mostly out of the sight of humans and predators. Just about all of the info I have read about any species in the wild is about adults.

Dana, you have a point. I have seen aquatic turtles with malformed carapaces due to poor diet, MBD, bad conditions, or a combo of any of these things, but I would not call them "pyramided" the way a sulcata, star or leopard looks. An aquatic turtle has to be in relatively bad shape to show such carapace malformations, but a tortoise can be relatively healthy, in good conditions, with a good diet and still pyramid.


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## Madkins007 (Feb 20, 2012)

The high carb/low carb is based on what grows when rather generically across geological regions (few carbs in dry grasses, etc.), the field observations are mostly Andy's in his most recent posts (http://www.tortoisetrust.org ) 

'Hunkering down' when it is dry/hot and not eating is basically aestivation, and that is another aspect of this whole issue. I suspect that most species of tortoises stop eating or really cut back for longer than we recognize. Even red-footeds in the Gran Chaco area aestivate.


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## Tccarolina (Feb 20, 2012)

Madkins007 said:


> The high carb/low carb is based on what grows when rather generically across geological regions (few carbs in dry grasses, etc.), the field observations are mostly Andy's in his most recent posts (http://www.tortoisetrust.org )
> 
> 'Hunkering down' when it is dry/hot and not eating is basically aestivation, and that is another aspect of this whole issue. I suspect that most species of tortoises stop eating or really cut back for longer than we recognize. Even red-footeds in the Gran Chaco area aestivate.



Yeah, it makes sense that many if not most species would aestivate.
Steve


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## Tom (Feb 20, 2012)

supremelysteve said:


> Madkins007 said:
> 
> 
> > The high carb/low carb is based on what grows when rather generically across geological regions (few carbs in dry grasses, etc.), the field observations are mostly Andy's in his most recent posts (http://www.tortoisetrust.org )
> ...



I think this is a lot of speculation. It is also going to vary with each species, I suspect. I was always told that sulcatas aestivate all the way through the long hot dry season. That they may only find some sparse dead grass to eat. I believed it too. In November I met a man who actually lives in sulcata territory and has studied them for decades. He told me that they eat very well in the dry season. Apparently, toward the end of the rainy season they gather up lots of fresh grass and drag it into their burrows. They line the entire bottom of their burrow with it and then eat it until the rains come back.


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## Tccarolina (Feb 20, 2012)

Tom said:


> supremelysteve said:
> 
> 
> > Madkins007 said:
> ...



Did he seem believable? How would a tortoise carry grass? One mouthful at a time? This sounds comical! Not saying it isn't true, but did he have any photos or proof? 

Steve


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## GeoTerraTestudo (Feb 21, 2012)

DanaLachney said:


> Well if you think about it you very seldom see Pyramiding in aquatic or semi aquatic turtles because they are wet correct? So common sense would tell you moist conditions for growing torts would work better than dry ones right?





Tom said:


> Dana, you have a point. I have seen aquatic turtles with malformed carapaces due to poor diet, MBD, bad conditions, or a combo of any of these things, but I would not call them "pyramided" the way a sulcata, star or leopard looks. An aquatic turtle has to be in relatively bad shape to show such carapace malformations, but a tortoise can be relatively healthy, in good conditions, with a good diet and still pyramid.



I should've known this thread would turn into a pyramiding debate. Well, so be it! 

I think moisture is only part of the story when it comes to pyramiding. Yes, aquatic turtles are, of course, wet moist of the time, while their cousins on land are drier. So, this could help the shells of aquatic turtles stay smooth, while those of tortoises may pyramid to one extent or another. But there's more to it than that.

Box turtles are a pond turtle that live on land, but I have never seen one with pyramiding. Yes, like any animal, they can develop problems if not properly cared for, but pyramiding does not usually appear to be one of those problems. True, many box turtles naturally live in wetter environments, but western boxies are native to drier grasslands and deserts (like tortoises). Either way, in captivity, they don't really pyramid. Why?

When a carapace pyramids, it's not just the keratinous scutes that form a hump, but also the underlying bone. If bone is involved, that means metabolism must be involved. Bone is affecting by growth rate, calcium availability, and vitamin D3 concentration. If people are doing something to make the bone grow too fast, or if they are not providing calcium and/or vitamin D3, then the bone may not be dense enough and take on a hump shape.

It seems to me that tortoises are more vulnerable to pyramiding than pond turtles (including boxies) precisely because tortoises are herbivorous, while pond turtles are omnivorous or carnivorous. Prey is more nutritious than plants, and as long as an animal's gut is adapted to it, a predator is going to have an easier time obtaining the necessary protein, vitamins, and minerals than an animal that must graze or browse.

I think pond turtles are less vulnerable to pyramiding because their diet allows their carapacial bones to grow more evenly than those of herbivorous tortoises. Yes, moisture does appear to be part of the equation, perhaps because of its effect on the keratinous scutes. But when it comes to bone growth, I think that has more to do with nutrition.



supremelysteve said:


> Tom said:
> 
> 
> > I think this is a lot of speculation. It is also going to vary with each species, I suspect. I was always told that sulcatas aestivate all the way through the long hot dry season. That they may only find some sparse dead grass to eat. I believed it too. In November I met a man who actually lives in sulcata territory and has studied them for decades. He told me that they eat very well in the dry season. Apparently, toward the end of the rainy season they gather up lots of fresh grass and drag it into their burrows. They line the entire bottom of their burrow with it and then eat it until the rains come back.
> ...



That is _very_ interesting. Animals like rodents and pika (a kind of mountain rabbit) carry grasses in their mouths to their dens for bedding and winter forage. Could it be that tortoises can do the same thing? Tom, who was this researcher, and has he published anything on his observations of this behavior?


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## Tom (Feb 21, 2012)

supremelysteve said:


> Tom said:
> 
> 
> > supremelysteve said:
> ...



Totally believable. He said they use their "shoulders" and their gulars. He made some motions demonstrating how they do it. It occurs to me that I have also seen my sulcatas bulldozing through tall weeds and dragging a bunch along with them. Mine don't have a burrow and their house is already lined with bermuda hay...



Geo, about your assumptions and the bone malformation. I don't think that it necessarily has anything to do with metabolism. As an example; are you familiar with the mechanical bone stretching medial techniques? How about braces? Yo know, like on people's teeth. There is no metabolic process involved in straightening someones teeth. It is persistent mechanical force that causes the teeth to realign and the sockets that hold them to readjust. I believe the same sort of forces are involved in the bone underlying the dry malformed keratinous scutes. I think the scutes "pull" the underlying bone into its misshapen form.

The Researcher is Tomas Diagne of the African Chelonian Institute.


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## Neal (Feb 21, 2012)

GeoTerraTestudo said:


> In my view, this is not necessary, adds effort and expense, and may even be harmful to these arid-adapted animals. Although they should have a moist substrate to burrow into, I don't think these species require elevated levels of ambient humidity. What do you think?



I don't know about high humidity being harmful, but I do agree with you that it is not necessary. I have raised smoothed shelled leopards, sulcatas, and indian stars without any elevated humidity...why do I have success doing things this way and others don't? I have no idea...and I'm not trying to play devils advocate here either, this has just been my experience and as we continue raising hatchling's we hope to find out more specifically why our method is working.

Interesting info to consider:

During the time of the TTPG conference a couple months back, I met up with a couple of forum friends for lunch. We sat next to someone who came from Tucson and he was showing us a bunch of pictures he had taken of wild Sonoran Desert tortoises. I can't remember how small he said the tortoises were...under 4 inches I think...anyway, there was a group of them in one area that was no more than a small eroded hillside which was completely exposed to the elements. It wouldn't do much to retain humidity in the Arizona desert. These tortoises were all smooth, and he was telling us that this spot is where they spend most of their time. 

Now, that's very limited info and you really can't make too many implications from that, but it raises the question in my mind...how are these tortoises so smooth without being in a humid environment?


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## GeoTerraTestudo (Feb 21, 2012)

Tom said:


> Geo, about your assumptions and the bone malformation. I don't think that it necessarily has anything to do with metabolism. As an example; are you familiar with the mechanical bone stretching medial techniques? How about braces? Yo know, like on people's teeth. There is no metabolic process involved in straightening someones teeth. It is persistent mechanical force that causes the teeth to realign and the sockets that hold them to readjust. I believe the same sort of forces are involved in the bone underlying the dry malformed keratinous scutes. I think the scutes "pull" the underlying bone into its misshapen form.



Fascinating hypothesis regarding pyramiding. And it could be true. Your project and a recent publication do appear to corroborate that explanation. If dry scutes are behind this, then they must be exerting a heckuvalot of force to be acting like medical braces. Sounds implausible, although certainly not impossible. But again, there are tortoises and turtles that live in dry environments that do not develop pyramiding. Either their scutes have some differences, perhaps at the microscopic level, that resist warping due to dryness, or else their metabolism is adapted to their arid-land diet, allowing the underlying bone to remain smooth. Or both. It's still not clear which is the cause and which is the effect: the warping of the bones, or the warping of the scutes.



> The Researcher is Tomas Diagne of the African Chelonian Institute.



Okay, I have heard of him, and was kind of wondering if that was whom you were referring to, actually. So you met him in real life? Awesome! What's he like in person?

Here's his Rolex Award website:
http://www.rolexawards.com/en/the-laureates/tomasdiagne-biography.jsp
http://www.rolexawards.com/en/about-the-awards/programme_news_africas_tortoise_saviour.jsp

*See also:*
TFO thread: "TURTLE AND TORTOISE PRESERVATION GROUP CONFERENCE THIS WEEK!"
http://turtlesurvival.org/component/taxonomy/term/summary/104/4
http://www.britishcheloniagroup.org.uk/conservation/conservation_projects.htm


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## Madkins007 (Feb 21, 2012)

Pyramiding always seems to come up in discussions about humidity. I wish we knew more about the mechanisms of pyramiding. It also threatens to take this thread in a lot of directions.

Tom- my comment about many species aestivating may yet apply in your example. His Sulcata seem to have found a 'loophole' around it- would they be aestivating if they did not have the cooler burrow and grasses? As for speculation- most of this discussion is speculation, isn't it?


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## GeoTerraTestudo (Feb 21, 2012)

Neal said:


> During the time of the TTPG conference a couple months back, I met up with a couple of forum friends for lunch. We sat next to someone who came from Tucson and he was showing us a bunch of pictures he had taken of wild Sonoran Desert tortoises. I can't remember how small he said the tortoises were...under 4 inches I think...anyway, there was a group of them in one area that was no more than a small eroded hillside which was completely exposed to the elements. It wouldn't do much to retain humidity in the Arizona desert. These tortoises were all smooth, and he was telling us that this spot is where they spend most of their time.
> 
> Now, that's very limited info and you really can't make too many implications from that, but it raises the question in my mind...how are these tortoises so smooth without being in a humid environment?



Bingo ... and that's where diet and metabolism come into play.



Madkins007 said:


> Andy Highfield's research seems to show that Mediterranean tortoises just plain don't spend a lot of time in places with significantly raised humidity, period.



I thought Andy Highfield showed that microclimates can make a difference in humidity. If an arid-land tortoise lives in an environment with a humidity of about 30%, hiding in a moist microclimate can raise the perceived humidity by about 20%, making the humidity in the immediate environment of the tortoise more like 50%. This may not be a big difference, but it can be of significant value to the tortoise.

Reference websites:
http://www.tortoisetrust.org/photos/spainhabitat.html
http://www.tortoisetrust.org/articles/microclimates.htm
http://www.tortoisetrust.org/articles/substrates.html
http://www.tortoisetrust.org/articles/pyramiding.html


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## GeoTerraTestudo (Feb 21, 2012)

BTW - I wonder one other thing about the proposed link between humidity and pyramiding. If dryness causes scutes and underlying bone to warp, why doesn't it do the same in comparable tissues in other animals?

Many animals (including turtles) have claws, hooves, or fingernails, which also consist of a keratin sheath overlaying bone. And what about the horns of bovids or rhinos? Why don't they get warped under dry conditions? The beaks of birds and turtles are also made up of keratin that lies atop bone. Yet, the only time they are misshapen is when they have either not been worn down through normal use, or else the animal has MBD that warps the jawbone itself. Dryness does not appear to affect the growth of the beak.

The shape of the keratin may have something to do with pyramiding, since scutes are flatter than structures like claws or horns, which are conical. However, our fingernails are flat, too, and although they can became misshapen from a variety of factors (including dryness), the effects are small compared to pyramiding and apparently limited to the nail, and do not include the phalanx bone.

Again, whatever role dryness plays in pyramiding, I suspect it is not acting alone, because diet and metabolism are probably just as important, if not more so.


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## chairman (Feb 21, 2012)

I read the original post as being about the roles of substrate humidity vs ambient humidity.

My personal experience on the matter is... my first tortoise was a Home's hingeback. I knew he needed humidity and I kept the ambient humidity upwards of 80%. I lived in FL at the time so it was really easy to do, I kept my windows open when temps were above 70 and never ran my air conditioning. However, I rarely added any moisture to the substrate, it was always fairly dry/dusty. That hingeback now has a reverse pyramided shell though he is otherwise quite healthy/active almost 10 years later.

About a year or so ago I picked up 2 juvenile Home's hingebacks, small enough to not have their hinges yet. I have raised them indoors in a climate controlled room with low ambient humidity (about 50-60%). I keep their substrate nice and moist and their shells get misted twice daily. They have grown quite a bit in the last year and are not reverse pyramided.

My sulcata, which I got slightly pyramided at around 4", was raised from that point with high substrate humidity and low ambient humidity and all her new growth is smooth. I probably got her a little too late in the game to accurately tell whether the growth had anything to do with husbandry, though.

So at least for me, with a humidity loving species, substrate humidity was significantly more important than ambient humidity, almost to the point where ambient humidity did not matter at all. I also misted shells, so my results could be placed in the keratin hydration camp as well. 

I suppose you could also argue that for any tortoise, any micro-climate they live in really only extends a couple feet below ground to a couple feet above ground. Whatever else is happening outside of those few square feet surrounding the tortoise, including "ambient" humidity, could be completely irrelevant. From that perspective, I would imagine that the humidity within the first couple inches of the ground is likely to be much higher than the humidity a couple feet above the ground pretty much no matter where you are in the world.


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