Reptile & Amphibian Forums

So, last year I went to a lecture given by a prominent tortoise physiology. In his lecture, he mentioned that when a desert tortoise in the wild emerges from its burrow, the plants first eaten by the tortoise will become the "ice cream plant," and the tortoise will continue to seek out only that type of plant for the rest of the season. This is due to the type of bacteria in the intestines that develop specifically for that type of plant. He stated that a tortoise's diet in the wild could be 90% the ice cream plant. If a tortoise tries to change the ice cream plant in the middle of the season, the amount of time it takes to change the gut flora could take up to two weeks and could be devastating to the tortoise.

So, what implications does this have for captive desert tortoises? Do captive tortoises have a more diverse flora in their intestines so they can handle the more diverse diet? My desert tortoises do not respond well to variety...I try offering a variety, but they pretty much just want their mazuri and dichondra. Are we forcing our tortoises to go beyond their physiology by not allowing them to have their ice cream food? If we feed our tortoises something different all the time, how are they dealing with that variety when it takes such a long time to change the bacteria in their intestines?

Do you think this is the same with other species of tortoise?

Would be an interesting research topic **hmmmmm**...

Keep in mind that the reseacher is also presenting a theory. I highly suspect that the tortoise does not seek out the plant because the bacteria is available to deal with it. I would think that the tortoise seeks out the plant because of availability and the bacteria developed in order to deal with it.

As to specific bacteria for a specific function... that is interesting.

This kind of comes back to a point I try to make on a regular basis. Tortoises seem to feed on what ever is available at the time and all that is available is not available all the time. Spring plants are different than Summer plants and so on. Also, I suspect the same plants will have a different composition throughout the year.

During this time of year the tortoises I have in the yard will key onto dried leaves. They will walk right by a green blade of grass of weed in the quest for dried leaves.

I keyed onto this when I was watching a Chuckwalla in Baja on one summer visit. The plants, which were sparce to begin with, were very dred out. The lizard would go from plant to plant and only eat the dried flowers.

Later, I noticed the same behavior in a CDT in the Mojave. It exhibited the same behavior which confirmed the observation that these animals key onto certain types of plants during certain times of the year.

So, in the big picture they eat many different things but on a narrower time scale they seem to eat a great deal of specific items.

I would think where this kind of research becomes daunting is that there are individual differences, specific differences, seasonal differences, cyclical differences... Try and come up with a control or pattern for that.
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Ed
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Trying to keep the fun in Chelonian care

Certainly is an interesting theory, but somethings about this theory don't jive. How did this guy check the gut flora from the animals? did he collect the poop? It does not make any scense that they would have a specific gut flora of one kind only for one type of plant. Did he wait for a tort to emerge from hibernation and feed it a bunch of romaine as a test? Why do the tort's need to develope new flora every spring? Does it die off during lowered temps in hibernation? From the biology classes I remember, most animals that eat a variety of foods, always have several kinds of flora and most types flora will work on many kinds of food.
I remember, when i was a kid in the 70's and 80's, going out to the northern mohave and I was able to view many desert tort burrows. It seemed like all burrows were either at the base of a creosote bush or in an embankment with the closest vegetation almost always creosote. This would probably be the vegetation the torts would feed on when emeging from hibernation (except for maybe desert wildflowers that are there for a very brief period before they die off and therefore would not be there to support specific gut flora). Maybe the the gut flora evolved to handle mostly creosote and that is why there was a specific majority of that flora.
Do you remeber the guys name and where the lecture was at? I am interested to know if he has anything published on this. Thanks
Elliott

I'll bet it was one of the presentations given by this organization.

http://www.deserttortoise.org/member.html

They do sell the proceedings from past years.
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Ed
Tortoise_Keepers-subscribe@yahoogroups.com
Trying to keep the fun in Chelonian care

The lecture was at Harvey Mudd College, given by Dr. Dick Tracey from the University of Nevada, Reno. I'm going to do a literature search tonight because all I have to back his word up is the notes from the lecture.

I did speak to my graduate advisor this morning about ice cream plants this morning, and he confirmed that the theory is generally believed to be true. We talked about how two people studying diet in desert tortoises will always be in conflict because there are significant differences between individual tortoises.

Thanks for the feedback...I'm playing around with a lot of ideas right now and hopefully I'll be able to mold something into my Master's thesis next year.