Discussion question: grassland tortoises

[CactusVinnie]

"According to Lockwood et al. (1994), rainfall in the Great Plains is heavier during the spring, but in Central Asia it is heavier during mid-summer."

Read more: http://www.tortoiseforum.org/Thread-Discussion-question-grassland-tortoises#ixzz1amoQsZMM

Hi, GTT!

Maybe in some parts that is true, but the typical Central-Asian climate, at least the one including most of A.h. habitat, is characterised by autumn-winter-spring rainfall and bone dry summers- that is the main reason why they are active only a short window in early spring to early summer: after that, the scorching heat and lack of rainfall kill all the annual weeds and force the tortoises underground. It is a rodent species too that follows the same pattern, forgot the name. The tulips too !
This can be seen checking the data for:
Kazakhstan- Almaty; Kyrgyzstan- Dzalal-Abad; Tajikistan- Dushanbe; Uzbekistan- Tashkent, Termez, Nurata; Turkmenistan- Ashgabat, Bayram-Ali; Afghanistan- Kabul, Mazar-i-Sharif; Pakistan- Quetta; Iran- Zahedan, Mashhad, Tabriz.

Cheers!

 

[GeoTerraTestudo]

consider more than just climate and those kind of conditions: if there is something that would compete w/a horsfield 'type' for resources in the great plains area, than that organism may be (or may have been) filling part or all of the 'small tortoise ecological niche' leaving no room for the n. american tortoises to adapt to live in that area/niche.

also, i don't know a lot about the range of the horsfield tortoises aside from country: uzbekistan, afghanistan, part of Iran etc...is it really inhabiting only steppes in these countries or is it in more rugged foothill type terrain? they kind of live in all sorts of terrain, aside from grasslands, don't they?

I think there may have been another constrain on tortoises that prevented them from colonizing the Great Plains. Turtles, Tortoises, and Terrapins by Fritz Jurgen Obst describes the steppe tortoise as the most widely distributed tortoise species in the world (for now!), inhabiting both steppes and deserts. These tortoises survive by living on slopes where they can dig their burrows, and have access to water and forbs (non-grass herbs). Without these features (slopes, burrows, water, and forbs), these small tortoises would be unable to survive in that climate. So, my question is, are there parts of North America that provide similar resources? I know we have deserts, grasslands, and hills, but do these areas have "diggable" (well-drained) soils where the tortoises could make their burrows? Are enough of these areas near water? Are forbs abundant enough to support tortoises? If not, then that could be the reason why the Great Plains are home to an omnivorous box turtle, instead of an herbivorous tortoise.

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"According to Lockwood et al. (1994), rainfall in the Great Plains is heavier during the spring, but in Central Asia it is heavier during mid-summer."

Read more: http://www.tortoiseforum.org/Thread-Discussion-question-grassland-tortoises#ixzz1amoQsZMM

Hi, GTT!

Maybe in some parts that is true, but the typical Central-Asian climate, at least the one including most of A.h. habitat, is characterised by autumn-winter-spring rainfall and bone dry summers- that is the main reason why they are active only a short window in early spring to early summer: after that, the scorching heat and lack of rainfall kill all the annual weeds and force the tortoises underground. It is a rodent species too that follows the same pattern, forgot the name. The tulips too !
This can be seen checking the data for:
Kazakhstan- Almaty; Kyrgyzstan- Dzalal-Abad; Tajikistan- Dushanbe; Uzbekistan- Tashkent, Termez, Nurata; Turkmenistan- Ashgabat, Bayram-Ali; Afghanistan- Kabul, Mazar-i-Sharif; Pakistan- Quetta; Iran- Zahedan, Mashhad, Tabriz.

Cheers!

Thanks for that information. Yes, one would think that North America's plains would be similar to Central Asia's steppes, but perhaps there are some subtle yet important differences in climate and food availability.

GBTortoises and some other members have said that they find steppe tortoises challenging to breed. I am surprised to hear this, and we have been debating the possible reasons for this in the "Hibernation for Testudo" thread. Some people seem to think that the change in seasons is more abrupt in Central Asia than in the Great Plains. Maybe our spring season really is rainier, and maybe this makes it more difficult for a tortoise coming out of brumation to forage. I don't know.

As I've said, it is my hope to get some land and a bunch of Russian tortoises here in Colorado, where they will hopefully breed pretty readily here, due to environmental matching. But judging by some other people's experiences, it might not be as simple as that. I guess we will have to see.

 

[CactusVinnie]

The soil types in wich A.h. live in Central Asia are various, from rocky, sandy to hard clay. I think that they adapt to borrow exactly to survive even in areas without much features, including plains. Another thing, most of them don't know how to drink!! That make sense, since pooling water is a such rare phenomenon there, that only dew and raindrops can be drinked, but our waterbowls and trays may eventually scare them, not to mention that sometimes they will not drink a drop!
I managed to "teach" them to drink, but they seem to forgot easy . More likely the CB babies will be familiarised with the water-tray.
As for the food, their favoured item for a good part of their active period is the Ranunculacean Ceratocephalus falcatus, a small poisonous weed tha killed some sheeps in Utah- I found that in US you call them "burr buttercup". The weed is already spreading well in the West and Great Plains/Midwest region. If you add bindweed, Taraxacum, Cichorium and other Asteraceae and Leguminosae, plus many other that we don't know about yet, it seems that the menu can be satisfying.
We had a dryish spring this year, and is the first spring here for my A.h.. But as you said, I really worry about a posible rainy one, like the 1997 spring, when I saw "The Crow" with Brandon Lee, and still remember the lyrics: "It can't rain all the time". That kept alive my hope that I will finally see the Sun after endless weeks of rain. I am sure that a spring like that would be no good at all for them... But Bucharest is wetter than most of Colorado, so your rainy springs may not be harmful for your A.h..
I wish you luck with your Russians project, I will be thrilled to hear that you succeeded!

 

[GeoTerraTestudo]

Thank you for your optimism, Fabian. It is very encouraging. I was beginning to think that maybe I was naive about the needs of steppe tortoises, but it sounds like they might do well here in a semi-wild state after all.

 

[GeoTerraTestudo]

The soil types in wich A.h. live in Central Asia are various, from rocky, sandy to hard clay. I think that they adapt to borrow exactly to survive even in areas without much features, including plains. Another thing, most of them don't know how to drink!! That make sense, since pooling water is a such rare phenomenon there, that only dew and raindrops can be drinked, but our waterbowls and trays may eventually scare them, not to mention that sometimes they will not drink a drop!
I managed to "teach" them to drink, but they seem to forgot easy . More likely the CB babies will be familiarised with the water-tray.
As for the food, their favoured item for a good part of their active period is the Ranunculacean Ceratocephalus falcatus, a small poisonous weed tha killed some sheeps in Utah- I found that in US you call them "burr buttercup". The weed is already spreading well in the West and Great Plains/Midwest region. If you add bindweed, Taraxacum, Cichorium and other Asteraceae and Leguminosae, plus many other that we don't know about yet, it seems that the menu can be satisfying.
We had a dryish spring this year, and is the first spring here for my A.h.. But as you said, I really worry about a posible rainy one, like the 1997 spring, when I saw "The Crow" with Brandon Lee, and still remember the lyrics: "It can't rain all the time". That kept alive my hope that I will finally see the Sun after endless weeks of rain. I am sure that a spring like that would be no good at all for them... But Bucharest is wetter than most of Colorado, so your rainy springs may not be harmful for your A.h..
I wish you luck with your Russians project, I will be thrilled to hear that you succeeded!

Yep, steppe tortoises appear to eat plants that are poisonous to mammalian herbivores, like buttercups when their parasite load gets too high. They appear to be medicating themselves (see "Article: steppe tortoise diet in the wild"). Then, when their parasite load decreases, they switch back to more palatable plants in the poppy and cabbage families, and especially the sunflower family.

As for water, though, I don't mean that they necessarily drink very much, although they might after a rain (Hermann tortoises have been observed to do this). My pet Russian tortoises rarely drink. Rather, I mean that the water (streams and rivers) support riparian vegetation, which the tortoises eat. Without the forbs that grow near water, deserts and steppes only support grasses and shrubs, which the tortoises can't really eat very much of. That's why they need the water: for the plants that grow near it.

I don't know how the Great Plains compare to the Central Asian steppes when it comes to rivers and streams. If we have fewer of them, then that might explain why there are no native tortoises here.

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Remember- we DID have tortoises here in Nebraska- a largish one Stylemys nebrascensis[\i] (http://www.bhigr.com/store/product.php?productid=448 if anyone has a spare $95, I would LOVE one of the replica fossil shells!) There is a site called Toadstool Geological Park (part of the Oglala National Grassland) that features several tortoise shell fossils from roughly 30-40 million years ago, and is not too far from the Hudson-Meng Bison Kill site. The soil is varied, but the presence of limestone suggests good calcium levels 'back then'.

There certainly has been climatic change since then, but another key issue is that there have also been several volcanic events. Much of Nebraska at one point or another was covered with ash from Yellowstone and other regional volcanoes. Thick layers of ash would have been a real problem for tortoises while other fauna could have avoided it in many ways.

I have often thought it would be interesting to see what would happen if you got several acres of suitable soil, plants, etc. in Western Nebraska and let a few hundred Russians loose. I suspect that in a few generations, we would have a strain that was pretty acclimated to our climate.

Yes, it is fascinating how the northern plains used to have a tortoise native to them. But this animal was the ancestor of today's Gopherus species. The environment has changed, but box turtles still live there. However, it has been 2 million years (when the Ice Ages began) since a tortoise has lived in the more northerly parts of America. But that is not the case in Central Asia. Amazing...

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It's an interesting question, but there are so many variables I don't think it's possible to get an answer. The very nature of evolution would make it impossible to answer.

What you are looking for is convergent evolution, two species from separate but comparable geographical areas and different taxa having similar characteristics to fill a similar niche in the ecosystem, such as some of the boas and pythons. It might be that another species filled the niche that another Gopherus species could have occupied.

It's possible that the environment is different enough that a tortoise just wouldn't fit. I would like to point out that the great plains we know today are VERY different from the plains of even ~150 years ago. Back then there were bison in vast numbers that would munch and trample huge areas, and there were the Rocky Mountain locusts (largely forgotten now but a large deal back when) that decimated huge areas of the plains, and other species that were introduced or have since gone extinct. Maybe not so great for a tortoise.

consider more than just climate and those kind of conditions: if there is something that would compete w/a horsfield 'type' for resources in the great plains area, than that organism may be (or may have been) filling part or all of the 'small tortoise ecological niche' leaving no room for the n. american tortoises to adapt to live in that area/niche.

also, i don't know a lot about the range of the horsfield tortoises aside from country: uzbekistan, afghanistan, part of Iran etc...is it really inhabiting only steppes in these countries or is it in more rugged foothill type terrain? they kind of live in all sorts of terrain, aside from grasslands, don't they?

It is possible that there are other, non-tortoise herbivores that have made it impossible for a tortoises to become established in the Great Plains, e.g. bison. However, Central Asia (at least until historical times) used to have a very similar fauna to North America. Both regions had bovines, horses, camels, and their attendant guild of carnivores. But the gopher tortoises never evolved a "horsfield-type" species the way the testudos did. Could just reflect the random-like nature of evolution. Very hard to say. But I find it fascinating to contemplate.

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[GeoTerraTestudo]

consider more than just climate and those kind of conditions: if there is something that would compete w/a horsfield 'type' for resources in the great plains area, than that organism may be (or may have been) filling part or all of the 'small tortoise ecological niche' leaving no room for the n. american tortoises to adapt to live in that area/niche.

also, i don't know a lot about the range of the horsfield tortoises aside from country: uzbekistan, afghanistan, part of Iran etc...is it really inhabiting only steppes in these countries or is it in more rugged foothill type terrain? they kind of live in all sorts of terrain, aside from grasslands, don't they?

Bump - Yes, I'm beginning to think prairie dogs might be a major reason why there are omnivorous box turtles here in North America's steppes, but no tortoises. I think prairie dogs would out-compete herbivorous reptiles here.

Here's a cool picture of Testudo horsfieldi in its natural habitat: