DO TORTOISES INSTINCTIVELY KNOW WHAT'S GOOD FOR THEM?

[kastalarial]

I've been observing my sulcata grazing. He seems to be eating everything in his path except a few plants like, potato leaves, papaya leaves and other vines. Also, he are a leaf mixed with the grass he's grazing and suddenly backed off after biting it. Correct me if I am wrong but I assume tortoises, which have been in this earth long before we did, instinctively know which plants to avoid and which will be best for them

 

[Jacqui]

The behavior of the vast majority seem to point to this being correct and then you come across the one who will eat any plant. They also eat things you would think they would know are not good for them like rubberbands, nails, cigarette butts. Of course none of these are found naturally in their native worlds. There is also the question that they may know what plants are okay to eat in the area where they are found naturally, but do they know the ones found in other locations/countries as well? Is yours just reacting to tastes and smells as reasons to reject the plants along his path or is it really knowledge that it is harmful?

Because of these unanswered questions and that each tortoise has it's own unique behavior that most folks go for warding off problems and just remove any believed to be dangerous plants or atleast limit them. Even then we have huge holes in our knowledge, as to what really is dangerous for a tortoise to eat and is each species unique within itself to the effects.

 

[JoesMum]

I think they do have an instinct... and they probably learn as well.

Plants give off all sorts of signals that they're not good to eat and I suspect that tortoisees are rather better at reading them than we are.

I have never bothered to pull up plants on the 'poison' list to stop Joe ingesting them. When he's out in the garden, he just doesn't eat them.

 

[kastalarial]

Yeah, I noticed my tort trying to munch a cig butt then he dropped it, next morning he came across another and smelled it then walked away.

 

[Madkins007]

Tortoises are NOT considered to have a high 'dietary IQ'. The higher the dietary IQ, the more consistently an animal will pass on an attractive or tasty food in favor of a healthier item. The lower the dietary IQ is, the more often the animal will go for looks and taste over healthfulness. Other aspects of dietary IQ is knowing when to stop eating, and so on.

People in the US generally have neutral-to-low dietary IQ's- we will almost always choose french fries over a plain baked potato, or ice cream over fresh fruit- and much of that seems to be based on how we have been conditioned by culture, how your family ate, advertising, etc. People on diets low in fat, salt, and sugar seem to loose at least some of that conditioning.

Tortoises are incredibly resistant to plant-based toxins, so there is not much edible in their ranges they cannot eat to some extent*. Even wild tortoises, however, will gorge on carrion, droppings, fallen fruits, and other things that certainly provide necessary nutrients, but they will eat it far beyond the need for those nutrients. On the other hand, these opportunities do not happen very often, so they may as well take full advantage of them. They have low dietary IQs but that works just fine for them in their natural settings.

(*- While lists of poisonous plants are often very long, you have to remember that many of the plants on the list are there because they are poisonous to humans or common domestic animals- very few of them have been tested on tortoises, and many are known to be eaten by tortoises with no apparent problems.)

It is worse in captivity where they are exposed to plants they have no experience with and strange and wonderful things to try to taste- dust bunnies, mulch chunks, power cords, etc. Combine this with the human tendency to offer foods that are overly rich in salt, fats, and sugars** and we have one part of the problem.

(**- even most human produce is higher in fats, salts, and sugars than wild plants are. That is why we intentionally bred nice fat sweet orange carrots from the skinny, purplish roots carrots started off as- just like we have done to almost every plant in the produce department.)

The other issue with the low dietary IQ is that they don't have much of an 'off' switch. Tortoises in the wild are forced by climatic conditions to deal with periods of abundance and scarcity. The warm rainy season brings lots of greens, fruits, and flowers, while the drier seasons push them to work harder to find less food- or even go dormant if it gets bad enough. They don't need to self-limit their intake- nature does it for them.

In captivity, we almost always offer the same abundant climate and diet. This is very likely a contributing element to pyramiding and other issues.

This is my 'bottom line' on this issue:
- If at all possible, a captive tortoise's main diet should come from a well-planted enclosure roughly simulating its natural habitat (including periods of abundance and relative scarcity). That let's their own dietary IQ work fairly naturally.
- If we are feeding it indoors, or supplementing an outdoor pen, we need to be responsible about both what we feed them, and what they might mistake as being food.

 

[Katherine]

Tortoises are NOT considered to have a high 'dietary IQ'. The higher the dietary IQ, the more consistently an animal will pass on an attractive or tasty food in favor of a healthier item. The lower the dietary IQ is, the more often the animal will go for looks and taste over healthfulness. Other aspects of dietary IQ is knowing when to stop eating, and so on.

People in the US generally have neutral-to-low dietary IQ's- we will almost always choose french fries over a plain baked potato, or ice cream over fresh fruit- and much of that seems to be based on how we have been conditioned by culture, how your family ate, advertising, etc. People on diets low in fat, salt, and sugar seem to loose at least some of that conditioning.

Tortoises are incredibly resistant to plant-based toxins, so there is not much edible in their ranges they cannot eat to some extent*. Even wild tortoises, however, will gorge on carrion, droppings, fallen fruits, and other things that certainly provide necessary nutrients, but they will eat it far beyond the need for those nutrients. On the other hand, these opportunities do not happen very often, so they may as well take full advantage of them. They have low dietary IQs but that works just fine for them in their natural settings.

(*- While lists of poisonous plants are often very long, you have to remember that many of the plants on the list are there because they are poisonous to humans or common domestic animals- very few of them have been tested on tortoises, and many are known to be eaten by tortoises with no apparent problems.)

It is worse in captivity where they are exposed to plants they have no experience with and strange and wonderful things to try to taste- dust bunnies, mulch chunks, power cords, etc. Combine this with the human tendency to offer foods that are overly rich in salt, fats, and sugars** and we have one part of the problem.

(**- even most human produce is higher in fats, salts, and sugars than wild plants are. That is why we intentionally bred nice fat sweet orange carrots from the skinny, purplish roots carrots started off as- just like we have done to almost every plant in the produce department.)

The other issue with the low dietary IQ is that they don't have much of an 'off' switch. Tortoises in the wild are forced by climatic conditions to deal with periods of abundance and scarcity. The warm rainy season brings lots of greens, fruits, and flowers, while the drier seasons push them to work harder to find less food- or even go dormant if it gets bad enough. They don't need to self-limit their intake- nature does it for them.

In captivity, we almost always offer the same abundant climate and diet. This is very likely a contributing element to pyramiding and other issues.

This is my 'bottom line' on this issue:
- If at all possible, a captive tortoise's main diet should come from a well-planted enclosure roughly simulating its natural habitat (including periods of abundance and relative scarcity). That let's their own dietary IQ work fairly naturally.
- If we are feeding it indoors, or supplementing an outdoor pen, we need to be responsible about both what we feed them, and what they might mistake as being food.

Great post. I couldn't agree more about being responsible not only for food items but also for what may be mistaken as food(gravel, ingestable substrate that can cause impactions and toxic plants alike) It's nice to think they may avoid toxic plants (most taste acrid anyways) but why risk it when you have complete control over your tortoises exposure to food and nonfood items?

 

[kastalarial]

Tortoises are NOT considered to have a high 'dietary IQ'. The higher the dietary IQ, the more consistently an animal will pass on an attractive or tasty food in favor of a healthier item. The lower the dietary IQ is, the more often the animal will go for looks and taste over healthfulness. Other aspects of dietary IQ is knowing when to stop eating, and so on.

People in the US generally have neutral-to-low dietary IQ's- we will almost always choose french fries over a plain baked potato, or ice cream over fresh fruit- and much of that seems to be based on how we have been conditioned by culture, how your family ate, advertising, etc. People on diets low in fat, salt, and sugar seem to loose at least some of that conditioning.

Tortoises are incredibly resistant to plant-based toxins, so there is not much edible in their ranges they cannot eat to some extent*. Even wild tortoises, however, will gorge on carrion, droppings, fallen fruits, and other things that certainly provide necessary nutrients, but they will eat it far beyond the need for those nutrients. On the other hand, these opportunities do not happen very often, so they may as well take full advantage of them. They have low dietary IQs but that works just fine for them in their natural settings.

(*- While lists of poisonous plants are often very long, you have to remember that many of the plants on the list are there because they are poisonous to humans or common domestic animals- very few of them have been tested on tortoises, and many are known to be eaten by tortoises with no apparent problems.)

It is worse in captivity where they are exposed to plants they have no experience with and strange and wonderful things to try to taste- dust bunnies, mulch chunks, power cords, etc. Combine this with the human tendency to offer foods that are overly rich in salt, fats, and sugars** and we have one part of the problem.

(**- even most human produce is higher in fats, salts, and sugars than wild plants are. That is why we intentionally bred nice fat sweet orange carrots from the skinny, purplish roots carrots started off as- just like we have done to almost every plant in the produce department.)

The other issue with the low dietary IQ is that they don't have much of an 'off' switch. Tortoises in the wild are forced by climatic conditions to deal with periods of abundance and scarcity. The warm rainy season brings lots of greens, fruits, and flowers, while the drier seasons push them to work harder to find less food- or even go dormant if it gets bad enough. They don't need to self-limit their intake- nature does it for them.

In captivity, we almost always offer the same abundant climate and diet. This is very likely a contributing element to pyramiding and other issues.

This is my 'bottom line' on this issue:
- If at all possible, a captive tortoise's main diet should come from a well-planted enclosure roughly simulating its natural habitat (including periods of abundance and relative scarcity). That let's their own dietary IQ work fairly naturally.
- If we are feeding it indoors, or supplementing an outdoor pen, we need to be responsible about both what we feed them, and what they might mistake as being food.

Very well said!