Sulcata Growth - An Evolutionary Theory

[sulcatadude]

In sulcatas, it has been well documented that humid conditions contribute to accelerated growth and higher activity, and that dry conditions seem to slow growth and cause lethargy.

I think it's very possible that the specific effects of humidity levels on tortoises are adaptive, and that there are evolutionary reasons for this. In the Sahel climate of Africa, there are sometimes clusters of years with dry weather, followed by a cluster of years with higher-rainfall weather.

Perhaps higher growth during rainy periods is a way for a tortoise to speed up it's metabolism and "expedite" the maturation process during times of plenty, when both they and their offspring are most likely to flourish.

Similary, during periods with drier weather, it is best for activity to be slow and metabolism to be minimal while the arid climate makes foliage sparser. This also helps the tortoise survive these often-extended dry spells and make it until the next period of rain and humidity.

Therefore, perhaps both relatively dry and humid environments are "natural", but humid environments are more conducive to the goals we have in captive care which include observable growth, higher activity, and more reproductive behaviors.

 

[Tom]

Your theory makes some sense, but I have not found dry conditions to cause lethargy. In all of my years of incorrect "dry" keeping, all of my sulcatas were still very active. They grew slowly, stunted and pyramided, but they were very active and voracious eaters.

My theory is simply that good hydration helps all their internal organs and systems operate at optimal levels, even though they can survive just fine in less than optimal conditions.

 

[sulcatadude]

Your theory makes some sense, but I have not found dry conditions to cause lethargy. In all of my years of incorrect "dry" keeping, all of my sulcatas were still very active. They grew slowly, stunted and pyramided, but they were very active and voracious eaters.

My theory is simply that good hydration helps all their internal organs and systems operate at optimal levels, even though they can survive just fine in less than optimal conditions.

Much of my idea is speculation based on the info I've gathered at these forums in my short time as a tortoise owner, combined with my own background in evolutionary biology and breeding some other types of reptiles. Tom, a lot of your insight has been very persuasive and influential to me in how I'm choosing to raise my sulcata/s.

I have successfully bred veiled chameleons and various snake species in captivity, but tortoises are a new challenge, and a lot of fun to learn about! It's amazing how different the info in old caresheets are vs. what the current consensus is among successful owners/breeders.

 

[rideburton87]

I am new to tortoise keeping but have kept and successfully raised many different reptiles (mostly lizards). What you said does make sense. When I first got my sulcata (1month old) I kept him in a tortoise table and he didn't grow at all. After six months I bought a scale and he was 44/45g's and had dry skin. I found this website, read Tom's threads repeatedly, and built a closed chamber littlerly the next day. I found that my tortoise gained a few g's in a week and a month later he is growing very rapidly. He was, and is very active and eats his body mass in food every day. It puzzled me when he wasnt growing at first because he seemed very healthy. He always had a very healthy poop and ate as much as I would give him. But I do correlate his healthy growth now a days to his hot and humid environment along with daily soakings and sprays. Nothing else I have done has changed such as diet and what not.

My tortoises are kept in a closed chamber by the way..

 

[EKLC]

In the wild a tortoise would find a way to limit his water loss in times of dryness. In an enclosure it would be very hard to create a environment that is dry, yet has areas where a tortoise could seek refuge, since a small volume of soil can quickly lose its moisture. So it is better to err on the side of caution and make it easy for them to stay hydrated.

I also am not sure that there would be any benefit in giving them a need to slow down for awhile until water became available. Even if it is natural, that doesn't mean that it is necessary or even beneficial. It's sort of like predators, which are natural, but we certainly don't try to simulate those for our torts.