Any Amazon Basin Yellowfoot Keepers Out There?

[Madkins007]

Eric makes an interesting point. The 'giant' red- and yellow-footeds do not seem to follow a lot of rhyme or reason in their locations (other than the southern reds being bigger, usually, than the northerns). There is a LOT of speculation about that- races or gene pools, dietary availability, other quirks, or just plain lucky enough to live long enough to get really big? I tend to think it is mostly the latter- lots of reptiles, fish, etc. just grow all their lives.

Also, "Vargas-Ramirez, Mario and Jerome Maran, Uwe Fritz. "Red- and yellow-footed tortoises, Chelonoidis carbonaria and C. denticulata (Reptilia: Testudines: Testudinidae), in South American savannahs and forests: do their phylogeographies reflect distinct habitats?" Organisms, Diversity and Evolution, 2010." shows little genetic variation in yellow-foot, unlike the 5 groups of red-foot he found.

I think, and this is strictly my opinion, that the phrase 'Amazon Basin' here is a marketing tool, like the thankfully dwindling use of 'dwarf' for some cherry-heads... which is also a marketing term for Eastern or Brazilian reds.

 

[Baoh]

If it was simply dietary availability, then the ones growing up in the states over the last couple of decades ought to be enormous with the diets of rich foods many give.

Additionally, with respect to being older, that is possible, but a number of animals have "younger" shell conditions in addition to a number whose shell conditions are "older". Additionally, growth continues, but also slows. Rate will diminish. Are these animals a couple centuries in age? More?

I could see a "giant" gene or, alternatively, some kind of regulatory mechanism that has become dysfunctional, leading to greater size.

Amazon Basin is just a marketing label in the same way as the word "cherryhead" can be used, too. The Amazon Basin is enormous and most yellow foot tortoises will be from it.

 

[Len B]

Here are some pics of my first yellow footed tortoise. These pics are over 40 years old, and at that time it was thought that all yellow foots could get this big.They were expensive even then, this one was $200. plus shipping cost in 1971. He had a lot of health issues that were not completely understood and the treatments were mostly guess work. He lived with me for about 2 years before passing. I still have his shell.

 

[Baoh]

It would be cool if Dr. Sam would post photos of his animals here, too. He has some nice-sized females.

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Len, your photos of him always make me envious.

 

[EricIvins]

What I've noticed, and as evidenced in this thread, is that none of these animals pictures are phenotypically the same. They all "look" different, which is why I believe in my theory...

 

[Baoh]

I neither agree nor disagree with your hypothesis. Not enough information to conclude and certainly a lack of any decent testing/research into this specifically.

I agree that there are different body types among the giants and that they are found in multiple regions in the range of the species. Heck, I have a relatively large Heinz 57 female, but she is not like any giant I have ever seen. Maybe in another ten years things will seem different. For now, she is just the big girl who liberates me from having to pick up after my two dogs. Oh, and hybrid base material.

 

[Jacqui]

I have interacted in person with one of the giants at the STL zoo. I plan to get around to a more extensive experience one of these days.

I was able to get close to one of these the other day. I was blown away with how big they really are.

 

[Madkins007]

(Dang. I had a reply and somehow erased it. Hate it when that happens!]

Diet: I don't think we can automatically equate rich captive diets and long life. In a lot of other situations, rich diets result in shorter lifespans due to the stresses on organs, such as fatty kidney, etc. 'Forced growth' programs in reptiles also seem to often result in shorter lifespans.

Shell conditions: This would carry a lot more weight if we had a reference set of shells from wild tortoises of known ages to compare them to. Same with growth rates. Most of what we think we know about this species (and others) comes from captive animals, which may not work for wild populations.

Gene: I don't doubt that there is a strong genetic influence. The question then would be if it is an individual quirk, or a population characteristic.

Age: If common boxies and snappers can be reliably aged at over 100 years old, I don't see why wild yellow-footeds or other species could not also hit 100, or even well beyond. The small number of 'giants' would seem to support the bell curve of ages one would expect from a wild population- most dying at 'middle age' with fewer surviving every year after.

Like so many other issues, it is probably some combination of the above and more. I just think that we humans sometimes forget that there are species out there that do not age the way we do, and that have significantly longer potential lifespans than we do.

 

[Baoh]

(Dang. I had a reply and somehow erased it. Hate it when that happens!]

Diet: I don't think we can automatically equate rich captive diets and long life. In a lot of other situations, rich diets result in shorter lifespans due to the stresses on organs, such as fatty kidney, etc. 'Forced growth' programs in reptiles also seem to often result in shorter lifespans.

Shell conditions: This would carry a lot more weight if we had a reference set of shells from wild tortoises of known ages to compare them to. Same with growth rates. Most of what we think we know about this species (and others) comes from captive animals, which may not work for wild populations.

Gene: I don't doubt that there is a strong genetic influence. The question then would be if it is an individual quirk, or a population characteristic.

Age: If common boxies and snappers can be reliably aged at over 100 years old, I don't see why wild yellow-footeds or other species could not also hit 100, or even well beyond. The small number of 'giants' would seem to support the bell curve of ages one would expect from a wild population- most dying at 'middle age' with fewer surviving every year after.

Like so many other issues, it is probably some combination of the above and more. I just think that we humans sometimes forget that there are species out there that do not age the way we do, and that have significantly longer potential lifespans than we do.

I hate when that happens, too.

I do not think anyone has equated a rich captive diet to long life. No, not fatty kidney. Fatty liver. And rich does not have to mean fatty or extremely Caloric from primarily energetic macronutrients which are not essential rate-limiting contributors to lbm, but can simply mean rich in nutrients such as vitamins, minerals, fiber, and protein. I have never seen a study on forced growth showing shorter lifespans, but I am also not speaking about forced growth. Greater building block availability for structural and functional foundations is all.

The shell condition has tons of variability. I have seen giants with non-abraded shells showing the surface annuli on a few individuals, but most without. That non-abraded ones exist makes me think highly advanced age may not be a simple causative factor.

I have no opinion on any sort of co-localized population. All genes are quirks with differing frequencies. If this is infrequent (as it so seems), however, it does not matter to me whether there is a population or not. Pair large with large and beget large in the F3s if not the F2s.

No one said they cannot reach an advanced age, but there is no data collected indicating that is the determining factor for these animals. Gaussian distributions are born of plotted data and you fit the distribution to the data, not the data to a Gaussian distribution. Given that offspring mortality is so high in nature, the distribution will NOT be bell-shaped and the left tail will be a whale, with reduced incidence of mortality as the animals grow ever larger from all predators except one. Man.

Maybe you forget. I have not forgotten. I simply do not see it as the causative factor because of some animals which are not all that old and plenty of old animals which are not all that large.

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I have interacted in person with one of the giants at the STL zoo. I plan to get around to a more extensive experience one of these days.

I was able to get close to one of these the other day. I was blown away with how big they really are.

Where did you interact with these? Any extra information you could share would be welcome.

 

[Madkins007]

Baoh-

My bad. When I rewrote (and totally hacked) the erased reply, I did not take time to re-read your original note. I plead fatigue for that and things like the kidney/liver flub. Sorry! In my mind the comment about rich diet was linked to longevity. Your point, however, was size.

I'm not even going to try to unravel my overly convoluted thoughts in that reply- the first version made a lot more sense.

However, on a slightly different version of this topic- have you read what South American Tortoises has said about this issue in pp. 90-91?

 

[Jacqui]

I have interacted in person with one of the giants at the STL zoo. I plan to get around to a more extensive experience one of these days.

I was able to get close to one of these the other day. I was blown away with how big they really are.

Where did you interact with these? Any extra information you could share would be welcome.

I'm sorry, I thought I said it was one of those from the STL Zoo that you were talking about. Well actually there were two in the off exhibit enclosure. This one was right next to and under me with only that fence between us. So not much "interaction" as such, just more a Wow! moment and one of the biggest highlights of the TSA meeting for me. I had heard about them from in here, but did not really visualize them being so big.

 

[Bryan]

The pair of yellows that I've seen here is supposedly 60ish years old and they weren't all that big at all, yet the Amazon Basin YF that my friend grew up to at least 50lbs. was about 20 years old. I suppose it could be a throwback gene of some sort, but I am of the belief that this is at least a subspecies. This would be the equivalent of a RES that's 21" long, how often have you seen that? Maybe they are late to mature and because of their size in the wild they are highly prized for food and they don't get to reproduce much so it's a very scarce animal basically on the verge of a collapse? That would make more sense to me than some of these other theories and it would mesh with what Eric is saying in that he has seen large animals from throughout their range. The sheer size difference just does not compute for me especially when I've seen older animals who were far from huge and a fairly young one that was a mini tank and was closer to a small Sulcata's size than a YF's.

 

[cdmay]

Ah, the mythical "Amazon Basin" Yellowfoot.....


I don't believe they exist. Yes, we do see large Yellowfoots from time to time. However, I don't think I've ever come across a verified "population" of these animals. Just a few stragglers here and there. Maybe one animal comes in larger than 25" in any given year. Only one has come in from Guyana in 2013 and it was damn near 29" SCL. Yes, I have seen the Peruvian "farmed" animals in person when they came in last. Even had the chance to compare them to Guyana Yellowfoots at that time. I could find no difference between the two. Yes, I have seen the pictures of big Yellowfoots at the farm that supposedly produced them. I have seen pictures of Peruvian Yellowfoots in situ and their sizes were comparable to Northern Shield animals. Take a look at the link -

http://www.understoryenterprises.com/tortoises


With that said - Are there big Yellowfoots endemic to Peru? Maybe. The best detective work I've done into these Unicorns of the Tortoise world place them in the middle eastern parts of Brazil. Again, still no evidence of a population though. Just a few large animals here and there. It will be awhile before anyone really does any type of in situ research on these animals. What I have found isn't much, save for a few pictures of a few large animals being slow roasted on a fire pit over the years...

Brilliant. I couldn't have said it better.
I too have seen literally many hundreds of imported yellow-foots as well as many photos of wild animals in Peru and Brazil and there is no rhyme or reason to the really big ones.
True, imported animals are not a reliable source of stats for over sized animals since it makes no sense to take up shipping space and weight with one tortoise when you can ship five smaller ones for the same amount. So there is some bias when looking for giants in a group of imported animals. But it is true that in a given shipment of adults there are individuals that are clearly older and yet much smaller than others in the group. This means that individual adult yellow-foots can vary quite a bit in size with some being noticeably smaller. It would follow that there are others that are corresponding larger in a given population.
But as Pritchard brought out in his Turtles of Venezuela and as stated by Ivins above, 'giant' yellow-foots seem to occur randomly.
The largest yellow-foots I've ever seen where two that were kept at the old Crandon Park Zoo in Miami before it folded. I never measured them but I promise that they were pushing 30 inches. Others who knew of them at the time used to confirm that size in conversation. They were kept with the Galapagos tortoises and basically looked like slightly smaller and much flatter Galaps.
**** Bartlett had two Peruvian yellow-foots for close to 30 years that he said were from an area that produced giants. Despite a rich captive diet they only grew to be about 16 or 17 inches.
There is also a great deal of variation within populations of red-foots as well. Eric Holt manages a group of nearly 500 adults from Suriname that have been in captivity for many years. Some of the males of this group are absolutely huge and much larger than what most people would assume is normal for Suriname animals. This male is big but is by no means the largest of his group. There are others he keeps that are a good bit larger. I only photographed this one because of his neat shell shape.

 

[Bryan]

Interesting Carl, how big would you say Eric's biggest RF's are?

 

[cdmay]

Interesting Carl, how big would you say Eric's biggest RF's are?

I know he has some 16 and 17 inchers.

 

[Bryan]

Interesting Carl, how big would you say Eric's biggest RF's are?

I know he has some 16 and 17 inchers.

Quite large indeed. Why would you think that there is such a wide range in the sizes of Yellowfoots vs. Redfoots?

 

[Baoh]

I'm sorry, I thought I said it was one of those from the STL Zoo that you were talking about. Well actually there were two in the off exhibit enclosure. This one was right next to and under me with only that fence between us. So not much "interaction" as such, just more a Wow! moment and one of the biggest highlights of the TSA meeting for me. I had heard about them from in here, but did not really visualize them being so big.

Apologies. I asked just so I was clear on it.

---

The pair of yellows that I've seen here is supposedly 60ish years old and they weren't all that big at all, yet the Amazon Basin YF that my friend grew up to at least 50lbs. was about 20 years old. I suppose it could be a throwback gene of some sort, but I am of the belief that this is at least a subspecies. This would be the equivalent of a RES that's 21" long, how often have you seen that? Maybe they are late to mature and because of their size in the wild they are highly prized for food and they don't get to reproduce much so it's a very scarce animal basically on the verge of a collapse? That would make more sense to me than some of these other theories and it would mesh with what Eric is saying in that he has seen large animals from throughout their range. The sheer size difference just does not compute for me especially when I've seen older animals who were far from huge and a fairly young one that was a mini tank and was closer to a small Sulcata's size than a YF's.

I am disinclined to/from the subspecies idea because of the distribution and body types. I do not think exceptional age offers a sufficient explanation.

 

[Kapidolo Farms]

In 1994, an Australian man who started an NGO, 'ZooPeru' sought funding to modernize a zoo in Peru. At that point in time the zoo served, to some extent, as a live animal food market. He gave a talk at the Philly Zoo, with many slides.

One such slide of a Tapir pen, also had well over 50 yellow foots that were all over 30 kilos each.

After his talk I asked him about all those tortoises. He said, they had just been in holding for Easter, that they where "fish" and could be eaten.

So from this little bit of an anecdote we can draw at least two conclusions.

1, there had been a relatively localized occurance of giant yellow foots near the zoo.

2, people selectively have harvested the biggest ones for food.

In follow up with the ZooPeru guy the slide, an actual film slide, has been lost, as have those animals.

There is varying variation throughout the range. Larger animals have had selective pressure for human consumption.

An allele combination in one place or another over one period of time or another may be "adaptive" or not. It seems likely that the traits that allow giantism in yellow foots would be present throught the entire range, but expression has been limited by predation, or by environment localized in space or time.

These are common patterns and processes visible in a huge range of organisms.

Will

 

[Bryan]

That had to have been some sight Will, 50+ animals that were 65+ lbs each! Any idea how long it took them to collect all of those animals from the wild? If it was over a short period of time then it would lend credence to a specific population being rather large, if it was done over a long period of time then it might just be people collecting them little by little when they see large specimens.

 

[cdmay]

In 1994, an Australian man who started an NGO, 'ZooPeru' sought funding to modernize a zoo in Peru. At that point in time the zoo served, to some extent, as a live animal food market. He gave a talk at the Philly Zoo, with many slides.

One such slide of a Tapir pen, also had well over 50 yellow foots that were all over 30 kilos each.

After his talk I asked him about all those tortoises. He said, they had just been in holding for Easter, that they where "fish" and could be eaten.

So from this little bit of an anecdote we can draw at least two conclusions.

1, there had been a relatively localized occurance of giant yellow foots near the zoo.

2, people selectively have harvested the biggest ones for food.

In follow up with the ZooPeru guy the slide, an actual film slide, has been lost, as have those animals.

There is varying variation throughout the range. Larger animals have had selective pressure for human consumption.

An allele combination in one place or another over one period of time or another may be "adaptive" or not. It seems likely that the traits that allow giantism in yellow foots would be present throught the entire range, but expression has been limited by predation, or by environment localized in space or time.

These are common patterns and processes visible in a huge range of organisms.

Will

Good points. Interesting (and believable) anecdote too.