A wild Gopherus polyphemus (Florida gopher tortoise) browses upon leaves and flowers in its natural habitat: providing adequate diets in captivity is a challenge for keepers, but it can be done.
A practical guide to avoiding dietary disasters
Tortoise Trust guidelines for:
Feeding Leopard tortoises - Feeding Mediterranean tortoises - Feeding Redfoot and Yellowfoot tortoises - Feeding Wood turtles and Box turtles - Feeding Russian tortoises - Feeding Hingeback tortoises - Feeding Desert tortoises
By A. C. Highfield
Almost no topic is as confused and difficult for a beginner to understand than feeding tortoises in captivity. It is also true that no other subject is as riddled with misinformation and myths. The proliferation of inaccurate and often lethal advice on this subject in books, in magazine articles and on the Internet is astonishing. It is no wonder that many new keepers find themselves totally confused, and often end up making basic, but serious mistakes.
This is not a subject upon which it is easy to generalize. There are innumerable variables. Getting the diet right necessitates an understanding of an individual species’ nutritional requirements, an understanding of how environment affects nutritional needs, an understanding of basic food chemistry and some knowledge of the vitamin and mineral trace element metabolisms. Unfortunately, many of those who publish advice on this subject seem to lack such knowledge, and hence much of what appears in print and upon the Internet is incomplete, is based upon misunderstandings of these essential principles, or is a gross oversimplification. Whole books can be written on the subject of feeding tortoises and turtles in captivity, and indeed have been. Even genuine experts in this field often disagree upon the finer points. Most do agree on the basic principles, however.
The object of this present article is to ‘get you started’ with a simple, but safe and effective, basic diet which you can undoubtedly develop and refine further. The focus is on setting some basic ground rules that conform to the principle of ‘do no harm’. The guidelines presented here have been developed and tested over many years by the Tortoise Trust. We do not pretend that in the simple form presented here they represent an optimum in every case; they are, however, fundamentally safe and effective in practice. This is a good place to start if you are new to this subject and wish to avoid causing irreparable harm to your animals. More experienced keepers will refine these diets and optimize them for the individual species they keep, taking into account the age of the animal, its sex, alternative foodstuffs that may be available, and local environmental factors among other considerations.
For a much more detailed discussion of this topic, and to ensure that you understand the principles upon which these brief guidelines are based, please consult the references given at the bottom of this page.
We have also included a short ‘Feeding FAQ’ that attempts to answer some of the questions we are asked most often. Study these carefully.
First, a few important facts:
In the wild, tortoises tend to be browsers. They wander over quite a wide area and in the process take small quantities of a very wide variety of seasonally available food. Some species are known to consume up to 200 different kinds of plants during the year. The exact combination of plants, and their status, young, fresh and succulent or old and dry, varies seasonally. Even some true tropical species experience major seasonal (rainy/dry) variations in food availability. Redfoot and Yellowfoot tortoises from South America, for example, will eat a diet comprised almost exclusively of leaves and flowers for part of the year, changing to a diet heavily biased in favour of fallen fruits later in the year. In the case of Savannah and semi-arid habitat species, food availability often peaks during early spring, but is sharply reduced during the very hot summers experienced in such zones. In response, the tortoises may enter a state of estivation to conserve energy, ceasing all normal activity at such times. A tortoise’s diet changes continually throughout the year. From a fairly high moisture and protein content in spring, to a very dry, and often lower protein content later on. By wandering over a wide area, and by consuming such a variety of foods, tortoises ensure that their overall intake is well-balanced and can supply the essential mineral trace elements that they require for reproduction and healthy bone development. Even the best captive diets tend to be very restricted when compared to these natural feeding patterns.
An excellent diet for a captive-bred Mediterranean tortoise at the Tortoise Trust. These animals live in well-planted outdoor pens that have been seeded with appropriate vegetation that aproximates that found in their natural habitats.
Calcium and Vitamin D-3
Tortoises tend to be found in regions where the soils are relatively rich in calcium and other essential trace elements. They also have free access to sunlight for basking. Natural sunlight contains UV-B radiation which is required by the tortoise to internally synthesize vitamin-D3. This is required by the tortoise to enable it to use the calcium it consumes in its food. Without an adequate level of D3, this calcium is useless for building bones. In order to synthesize D3 properly, both UV-B radiation and radiant heat is required. For more on this subject see the ‘Reptile Lighting’ article referenced below. True rain forest species obviously cannot and do not bask to the same extent as species from deserts or plains. Their diets tend to be very different, in that such species are usually omnivores. Much of the vitamin D3 component they require is, in this instance, met from the animal component of their diets. They are therefore far less dependent upon basking than exclusive herbivores. This is merely one example of how environmental factors influence diet, and vice versa. Tortoises have quite a high demand for calcium in their diets, especially when undergoing rapid growth (a juvenile, for example) or in the case of egg-laying females. Such animals tend to actively seek out extra calcium to meet these needs. If it is not available, they can rapidly suffer deficiencies.
This California Desert Tortoise was raised on a high protein diet. This promoted rapid growth. The diet was also seriously calcium deficient. Instead of developing a normal, rounded carapace shape, it developed the typical lumpy, flattened form characteristic of MBD (Metabolic Bone Disease)
Habitat and diet
Tropical rain forest species encounter carrion and fallen fruits quite often. It is a typical feature of these environments. Species that inhabit dry, grassland savannahs or arid desert environments hardly ever encounter carrion or fruit, however. Both groups of tortoises have developed different ways of dealing with the foods that they naturally encounter. If you feed arid habitat tortoises large amounts of fruit it will cause severe digestive tract upsets, diarrhea, encourage the proliferation of digestive tract parasites such as flagellate organisms, and can even lead to sudden death from a maladjusted gut pH. By the same token, you cannot expect to keep a tropical rain forest tortoise such as an African Hingeback (Kinixys sp.) healthy on a diet of mixed grasses and hays. Such a diet is very well suited to a Leopard tortoise (Geochelone pardalis), but is completely unsuited to the needs of a species that has evolved to consume a combination of live prey, soft fallen fruits, and carrion. These are not dietary “preferences” - they are dietary imperatives. They are not interchangeable. Any attempt to do so invites very serious consequences indeed. These ill-effects may not show up for some time. It can even take years. By the time it does show up, however, it may well be too late to do anything about it. We cannot stress this enough: learn about the real needs of the species you keep and try to understand the reasons why it has those needs, and then try to find out how best you can meet them.
Commercial tortoise diets
It is worth commenting upon the canned (usually dried) 'complete tortoise diets' that are available in pet stores. These are advertized as complete, or almost complete, solutions to all of your tortoise nutrition concerns. Words such as 'scientifically formulated' and 'quality ingredients' are used to describe them. You may think you are safe relying upon such products. We have tested most of these products over the years, and in our view, they should be avoided. We have also seen numerous 'dietary disasters' attributable to their use. These products are usually extremely high in protein, and many contain high sugar levels in addition. They in no way approximate the natural diet of these animals. Rather than describe each one in detail, we will let the following pictures speak for themselves. These two animals, a Terrapene carolina (American box turtle) and a young Geochelone sulcata (African Spurred tortoise) were both raised from juveniles using T-Rex brand 'complete' tortoise and turtle diets.
Note the severe deformity at the rear of the carapace: a condition typical of animals raised on high protein, high growth rates and inadequate levels of calcium.
This Geochelone sulcata demonstrates the thickened keratin and 'pyramided' scute formation again typical of high growth rates sustained on a mineral deficient diet.
This is what healthy shell growth should look like. A Geochelone pardalis (Leopard tortoise) raised from a hatchling on the diet recommended by the Tortoise Trust. Note the very smooth carapace and even growth.
Our advice is simple. We see no need for these commercial feeding products and we believe their use is unsafe and is very likely to lead to the kind of severely deformed animals shown above. We strongly recommend that you avoid them.
FEEDING MEDITERRANEAN TORTOISES
The diet of Mediterranean tortoises (Testudo species) in the wild consists almost entirely of herbaceous and succulent vegetation, including leaves, grasses, flowers, and very, very occasionally fallen berries. Fruit is categorically not a regular or significant component of their diet. These tortoises are almost exclusive herbivores. They categorically do not consume meat of any kind in the wild, other than - possibly - on a very, very rare and opportunistic basis. It is in no way a regular part of their diet.
Look closely at this picture: it provides a rare insight into what Mediterranean tortoises really eat. This is a wild Testudo ibera in Turkey. Myself, Lin King and Jill Martin from the Tortoise Trust tracked these animals over many days to record their diet and behavior. No tinned dog food! No hard boiled eggs! No 'monkey chow'! No bananas! Just extremely healthy tortoises consuming a diet based entirely around the type of plants you see above....
I have personally worked with all of the Mediterranean species extensively, both in the wild and in captivity. In all of my years studying these tortoises in the field, I found not once single piece of evidence that any animal protein was deliberately consumed. The nearest I ever came was a Testudo graeca in Morocco that appeared to have consumed part of a dead beetle. This may well have been entirely incidental. At the Tortoise Trust we breed Mediterranean tortoises frequently. These hatchlings are reared to adults on 100% herbivorous diets. Claims that Mediterranean tortoises “need” meat in their diets are quite simply complete nonsense.
If Mediterranean tortoises "needed" meat or other high protein foods this extremely healthy, beautifully grown animal would be dead. It was reared exclusively on the type of diet recommended in this article.....
During episodes of rainfall tortoises will drink from the puddles which form, and they may also approach streams or ponds. They frequently pass urine at this time as well, and will simultaneously dispose of the chalky white uric acid residues which form in the bladder. It is categorically not true that wild tortoises rarely drink. I have seen both Testudo ibera in Turkey, and Testudo graeca graeca in Morocco approach streams and ponds and drink copiously, in addition to regular observations of drinking following rain. During the dry season, and in the more arid parts of their range, tortoises rely mainly upon the water content of their food in order to supply their moisture requirements. In captivity, we suggest soaking the tortoise for 10 minutes twice each week in fresh, shallow water to ensure an adequate state of hydration.
General rule for feeding Mediterranean tortoises
In captivity, a high fiber, low fruit content, low protein and calcium rich diet will ensure good digestive tract function and smooth shell growth.
Mediterranean tortoises fed on cat or dog food, or other high protein food items such as peas or beans, frequently die from renal failure or from impacted bladder stones of solidified urates. Peas and beans are also very high in phytic acid, which, like oxalic acid, inhibits calcium uptake. Avoid reliance upon ‘supermarket’ greens and fruits which typically contain inadequate fiber levels, excessive pesticide residues, and are too rich in sugar. Fruit should be given very sparingly or not at all as it frequently leads to diarrhea, intestinal parasite proliferation, and colic. We do not use fruit at all with our Mediterranean tortoises and we suggest you do the same. Unfortunately, it is all-too-common to see totally inappropriate and dangerous advice on feeding these species.One veterinary website published a truly appalling diet for Mediterranean tortoises, heavily biased towards root vegetables and fruit (both of which cause major gastric disturbance in these species), including peas and beans which are far too high in protein, have a terrible calcium to phosphorous ratio and are rich in calcium inhibiting compounds. It also includes cabbage family leaves to excess, and finishes up with meat and boiled eggs, neither of which I have seen lying around in any Mediterranean tortoise habitat I have yet visited…
Although it is difficult to tell, due to the extreme deformity, this is a Marginated tortoise, Testudo marginata. This animal was also raised on a high protein, calcium deficient diet This is a terrible example of what poor dietary management, and the feeding of meat based products will do to a naturally herbivorous tortoise. .
A diet like this fed to a rapidly growing juvenile will result in excess growth, poor bone density and metabolic bone disease, and it will throw in kidney damage for good measure. I would be surprised to see a juvenile reared on such a diet to survive for more than a few years. It would certainly exhibit severe shell and other developmental disorders.
Because they grow quite rapidly, and are actually developing their bone structure in the process, juvenile tortoises are exceptionally likely to suffer serious consequences from dietary mismanagement. There is no room for error at all when feeding hatchlings and juveniles. Just a few weeks on an incorrect diet can result in irreparable harm (adult female and her baby: Testudo kleinmani, the Egyptian tortoise).
A fully grown adult may survive longer, even on a truly terrible diet, but will slowly suffer serious liver and kidney complications over the medium-long term. Herbivores are not equipped to deal with large amounts of saturated fat, or with high protein intakes.
Unfortunately, advice of this calibre is in wide circulation, and many who do not know better (including many veterinarians), continue to assume that this is what tortoises need. Nothing could be further from the truth.
When planning a diet for captive tortoises, take their natural dietary behavior into account as fully as possible. In the case of Mediterranean tortoises, try to provide a mixture of edible flowers and leaves. Mulberry leaves and hibiscus leaves and flowers are excellent, for example. Opuntia cactus pads are also a great favorite and are rich in both calcium and fiber. A lack of dietary fiber, or roughage, will precipitate digestive tract disturbance, diarrhea and an apparently much increased susceptibility to flagellate and worm problems.
Root vegetables are far too high in readily digestible carbohydrates, and have no place in the diets of these species. Mediterranean tortoises should really be viewed as “goats in a shell”, and are similarly adapted to do best on what at first sight may appear to be a very “low quality” diet.
Although Mediterranean tortoises will take animal protein if offered (as will most normally herbivorous tortoises), in practice this leads to excessive growth and causes severe shell deformities, liver disease, and renal stress. It should therefore be avoided entirely. In our experience, tortoises that are fed animal protein suffer premature mortality. In other words - they die.
Another Desert tortoise raised on an unsuitable diet. This tortoise displays the raised, 'pyramiding' of the scutes that is so typical of poor dietary management. Juveniles are far more susceptible to this condition than adults as their bones become soft, porous and fibrous during growth phases instead of strong, dense and smooth. Compare with the smooth shell of the Mediteranean tortoise of the same age (reared on a correct diet) above.
A balanced diet for Mediterranean tortoises can include dandelion and a very wide range of naturally occurring non-toxic “weeds”. Do not use head lettuces such as iceberg, as these contain very little in the way of vitamins, fiber or minerals. There are several excellent resources available on the web where you find comprehensive lists of suitable food plants that are suitable for use in Mediterranean tortoise diets. Some of these are listed at the bottom of this page.
Captive-bred Mediterranean tortoises (Testudo ibera) raised exclusively on a herbivorous diet based upon the guidelines discussed here; high fiber, no fruit, rich in calcium, low in protein, no animal matter, and containing a wide variety of fresh edible "weeds".
Most Mediterranean tortoises fare best when allowed to graze, offering the other listed items as occasional supplements. Do not routinely offer cabbage, spinach, chard, bok choy, or any vegetable related to these, as they inhibit calcium absorption and can cause serious health problems. This is particularly critical in the case of juveniles or egg-laying females. The regular use of a cuttlefish bone or calcium block left in the enclosures allows tortoises to regulate the amount of calcium in the diet. Some tortoises like this very much, while others will refuse to eat it. Allowing Mediterranean tortoises to forage and graze naturally helps the tortoise to maintain good digestive-tract health, and greatly assists in the prevention of obesity. If scute pyramiding is noted, this usually indicates that either too much of the ‘right’ type of food is being consumed, or, more likely, that the overall protein content of the diet is too high and the calcium/D3 supply is inadequate. We recommend the use of a good quality phosphorus free calcium and vitamin D3 supplement at least twice per week, more frequently for juveniles and egg-laying females. A “raw” calcium supplement may safely be used on a daily basis. If the tortoise is maintained indoors for any significant period, be sure to make provision for UV-B exposure. The “Lighting” article mentioned previously should be consulted before deciding which lamps to purchase and for advice on how to install them.
Desert tortoise (Gopherus agassizzii) - in the wild it feeds on a variety of seasonal succulent plants, flowers, grasses and cacti. Like all arid-habitat tortoises it is a strict herbivore.
If you keep Desert tortoises (Gopherus agassizii) you will find that the above diet is also suitable, with minor modifications, as their requirements are very similar indeed to the Mediterranean Testudo species. The Russian tortoise, Testudo horsfieldii, though geographically not a Mediterranean tortoise, also has near identical dietary requirements.
The Russian, Steppe, Afghan or Horsfield's tortoise (Testudo horsfieldii): another strict herbivore from a harsh and arid environment. Overfeeding is a problem with this species in captivity.
FEEDING LEOPARD AND SULCATA TORTOISES
For large savannah species, such as Geochelone sulcata (African spurred tortoise) or Geochelone pardalis (Leopard tortoise), grasses and hays are a critical dietary component. Aldabra and Galapagos tortoises also do extremely well on this type of diet. Some other species also benefit from the inclusion of both fresh and dried grasses in their diet - although certain species, such as Redfoot, Yellowfoot, Hingeback and Mediterranean tortoises are ill-equipped to digest the high silica content of grass fodder. For species adapted to it, however, grass is not only nutritious, but its fiber content makes a significant contribution to digestive health. For leopard and African spurred tortoises, mixed grasses should comprise approximately 70-75% of the total diet.
A Geochelone sulcata enjoys a meal of mixed hays.Hay forms an important part of the diet of this and other grassland species.
Availability of grass types varies greatly according to location. The following list of suitable fodder grasses is based upon availability in the USA. In Europe, these particular species are rarely available - although local equivalents can usually be found. General “meadow hay” and “orchard hay” mixes are usually suitable, for example. Avoid hays that have excessively “prickly” seed heads - these can injure mouths or eyes. The use of coarse Timothy hay is excluded on this basis. Second or third cuttings of grass hays tend to have less spiny heads than first cuttings.
· Buffalo grass
· Couch grass
· Kikuyu grass
· Blue Grama grass
· Big Bluestem grass
· Darnel Rye grass
· Fescue sp. grasses
This grass-based primary diet should be supplemented with flowers as frequently as possible (Hibiscus, dandelion, petunia, Viola sp. etc.). De-spined Opuntia pads, clovers and other fodder ‘weeds’ listed previously should also be included on a regular basis.
Fresh green grass is also a favorite of Leopard and Sulcata tortoises
FEEDING INDIAN STAR TORTOISES
Indian Star tortoises (Geochelone elegans) have dietary requirements that fall mid-way between that of Mediterranean tortoises (Testudo species) and Leopard tortoises (Geochelone pardalis). In captivity, they should not be given fruit either in quantity or on a routine basis, or they will suffer serious digestive tract disorders. They need a diet which is very high in fiber, is low in sugars and easily digestible carbohydrates, and which is primarily based around coarse green leaves, mixed grasses, and flowers. Juveniles and egg-laying females require large amounts of calcium. Use a supplement - always. Good foods include:
Try to avoid a diet based upon 'supermarket salad'. This will not offer adequate fiber, and tends to be very poor in essential trace elements and other nutrients. Thousands of baby Indian Star tortoises are sold each year in some parts of the world as pets: the vast majority die within 12 months because the basic feeding advice given here is ignored. If you keep this species, you must provide an adequate diet and must ensure that both calcium and vitamin D3 needs are met.
FEEDING REDFOOT, YELLOWFOOT AND AFRICAN HINGEBACK TORTOISES
A wild Hingeback tortoise (Kinixys belliana) enjoys a meal of a live snail (photographed in the field, in South Africa). Snails and millipedes are a regular part of their diet.
These tortoises are basically omnivorous or a greater or lesser extent depending upon species. Include some low-fat animal protein in the diet of these species. Protein (or more probably, an amino-acid) deficiency has been noted in some Red-foot and Yellow-foot tortoises raised on entirely herbivorous diets. We recommend re-hydrating dried cat foots with additional minerals and vitamins as for turtles. Provide one meal per week containing animal protein. We now give about 25g (1 ounce) of moist cat food to a fully grown (10 kg/ 22 pound) Red-foot tortoise on a weekly basis (proportionally less for juveniles). Fruits are also part of the diet of these species in the wild - unlike Leopard or African spurred tortoises, their digestive tract copes easily with this richer, sweeter intake. The same frequency seems to suit Hinge-backs, which are also highly omnivorous in nature, but here approximately 5-10 g of animal protein per week is more appropriate (depending upon size). It is also important to note that these tortoises, if allowed access to a damp, moist garden or well vegetated tropical house will usually find slug, snails and night crawlers for themselves. This is both psychologically and gastronomically stimulating for them in addition to helping out with their owners' garden pest control efforts! Needless to say, never use slug pellets or other toxic chemicals in any garden where tortoises (of any sort) are kept. Millipedes and similar invertebrates constitute an important part of the diet of Kinixys sp. in nature.
FEEDING AMERICAN BOX AND WOOD TURTLES
These North American semi-terrestrial turtles are also omnivorous in their feeding habits. In the wild, they consume slugs, snails, earthworms and similar small prey as well as fallen fruits, mushrooms and some green leaf material. Juvenile box turtles are often almost exclusively carnivorous, their diet broadening out to include more vegetable matter with increasing age.
· Slugs, snails
· Earthworms, waxworm larvae, mealworms, night crawlers
· Fruit (most turtles prefer “mushy” over-ripe fruits rather than fresh)
· Green leaf vegetables
· Small quantity (low fat) dog food, thawed pinkie mice (for T. ornata)
It is a common myth that omnivorous turtles do not suffer from nutritional disorders to the same extent as herbivorous species. Not true. This poor box turtle (Terrapene carolina) was raised on a diet of canned dog food without adequate calcium supplementation....
As with all tortoises and turtles, great care must be taken to ensure a varied diet adequate in all essential trace elements. Regular supplementation of the diet with a multi-mineral powder is therefore recommended - extra calcium supplementation during their carnivorous phase is especially critical.
· Try to ensure that all diets are as varied as possible - in this manner a wider cross-section of natural trace elements will be made available.
· Do not dose with 'pure' vitamins unless under veterinary direction - some pure vitamins, including vitamins A & D, are highly toxic if taken in excess. These should only be used as part of a treatment program to correct a properly diagnosed specific deficiency.
· Provide vitamins orally rather than by injection, where required, unless there are compelling veterinary reasons to the contrary.
· The regular use of a safe, properly formulated multi-vitamin and mineral preparation will ensure that dietary deficiencies do not occur.
· The best supplements for tortoises are phosphorus-free, contain a wide range of mineral trace elements, include vitamin-D3, and are free of added amino acids.
· If you maintain tortoises outdoors in a geographical zone where natural UV-B irradiation closely approximates that of the habitat in nature, then you many not need to provide additional oral D3 supplementation, though calcium and other trace elements should still be provided. Keepers in northern climes are generally advised to rely upon oral D3 supplements.
· Artificial UV-B lighting may be used, but fluorescent tubes should be changed regularly (at least every 6-9 months) and multiple tube installations will be necessary to ensure adequate UV-B exposure for most species. The new UV-Heat self-ballasted mercury vapour lamps are excellent, and provide an ideal combination of high levels of UV-B and UV-A, with good quality visible spectrum rendering, with radiant heat for basking and improved vitamin D3 synthesis.
· Carnivorous turtles, and tortoises with a high degree of omnivory, will receive a significant proportion of their D3 needs from the animal protein proportion of their diet.
· Aim for a high calcium, low phosphorous content diet.
· Avoid plants high in oxalic or phytic acid.
TORTOISE & TURTLE FEEDING FAQ
(FREQUENTLY ASKED QUESTIONS)
These are real questions from real tortoise keepers. If you have a similar question that requires answering you can submit it to us at firstname.lastname@example.org .We cannot promise to answer it here, but if it is of general interest we may do so.
Q. I understand the need for a calcium supplement, but can I use egg-shells? I read somewhere that these are a very good source of calcium.
A. Eggshells are not a good source of calcium, in fact. They can also contaminate your animals with salmonella. A far better, safer source of calcium is plain calcium carbonate. This can be obtained very cheaply, in bulk, from animal feed stores. You can also use any food-grade calcium supplement, or any phosphorus-free specialty reptile supplement. We strongly recommend avoiding the use of poultry eggshells.
A. Flowers, leaves, seeds and grasses contain perfectly useable levels of protein, especially for the slow fermentation-based digestive tract of these tortoises. Think about some of the largest mammals around, elephants and giraffe! They are also exclusive herbivores and easily meet all of their protein requirements from the vegetation they graze upon. It is a common misunderstanding to assume that “meat = protein” and “vegetables = no protein”. This is completely untrue. Even some vegetable matter can be dangerously high in protein for tortoises; peas, beans, alfalfa and beansprouts in particular are far too high to be used safely.
Q. Can I use Tofu to give extra protein as it is derived from vegetable sources?
A. No. It is very high in protein, and is also high in phytic acid. In addition, it is very easily digested which means that it is even more damaging than feeding plain peas and beans. Tortoises that are maintained on a correct diet do not need ‘extras’ like this. It does far more harm than good.
Q. The reptile expert at the pet store says that all that a tortoise really needs is a vivarium and a diet of lettuce and fruit. Your site does not agree with this. Who should I believe?
A. It is very difficult for beginners when they receive such conflicting advice. Before we show you the actual effects of the method your pet store 'expert' is recommending, we would point out that pet stores are interested in making a sale. They also want to sell you expensive vivarium equipment in addition to the animal. We are not trying to sell you anything - we are merely trying to prevent your animal suffering as a result of incorrect advice. Our advice is free. We strongly recommend that if you are unsure, join the Tortoise Trust e-mail list. There are more than 1,000 keepers on that list from all over the world who can give you totally impartial help and advice. That said, this is what will happen to your tortoise on the diet this 'expert' is suggesting:
Russian tortoise (Testudo horsfieldii) raised in a vivarium tank and fed on lettuce and fruit. There is severe reduction and deformity of the carapace, typical of a diet that was grossly deficient in calcium and/or vitamin D3. The beak is also severely overgrown. Fishtank-type vivaria are NOT appropriate environments for terrestrial tortoises (see 'A Habitat for Horsfields' elsewhere on this website). Many thanks to tortoise rescuer Marty La Prees for donating this photograph. The tortoise is now in a suitable environment on a proper diet. Unfortunately, the deformity can never be reversed.
Q. One book I have says to feed cheese and boiled eggs to tortoises. What do you think?
A. Show me where tortoises get cheese and boiled eggs in the wild…. no, you should never feed items like this. Pizza, burger, ice-cream, bread, milk, donuts, monkey chow, vegetable oil or any one of a dozen other totally unnatural and inappropriate foods that might be ‘recommended’ by some books or websites also fall into the same category. There is a simple rule: if a tortoise does not eat the same item, or something very similar, in the wild there is no reason to offer it in captivity. It is not necessary and is far more likely to do harm than it is to do any good.
Q. My tortoise has a white, chalky discharge with its urine. I was told this means it is suffering from too much calcium in the diet - is this true?
A. No. Definitely not. This is uric acid, and it has nothing at all to do with calcium. It is a by product of the protein metabolism in reptiles and in birds. If it is concentrated and thick it suggests one of two conditions: an excess of dietary protein, or dehydration. It is normal to see some uric acid, but too much requires investigation and a possible change in your husbandry practices.
Q. Instead of using a calcium supplement, can I guarantee enough calcium intake by only choosing vegetables that have a better than 2:1 ratio of calcium to phosphorus?
A. In theory, yes. In practice, however, probably not. The difficulty here is knowing that the items you select contain the levels of calcium that you expect them too. Short of having each item analysed individually (hardly practical) there is simply no way of telling what they actually contain. Published tables look fine in theory, but they only give approximate averages, and produce typically varies from published levels by several hundred, or even several thousand percent. I would certainly not advise relying upon this kind of information for such a critical purpose. Adding a calcium carbonate supplement is 100% safe, and can guarantee that adequate levels are available.
Q. Why should I choose a “phosphorus free” supplement rather than a supplement that contains a 2:1 ratio of calcium to phosphorus? Isn’t phosphorus important too?
A. Yes, it is. It is also very abundant in just about all green, leafy vegetables and plants, and there is therefore no need at all to provide any more. It is calcium that tends to be seriously deficient in herbivore diets, not phosphorus. By using a 2:1 ratio supplement, you may increase the overall amounts of calcium and phosphorus available to your tortoise, but you will do nothing much to improve their ratio. You need an absolute minimum ratio of 2 parts calcium to 1 part phosphorus. This is a minimum, not an optimum ratio. We aim for a minimum 3:1 ratio. Many self-selected items in wild tortoise diets have a 5:1 ratio or better.
Q. Is it OK just to use calcium carbonate as a supplement, or should I be concerned about other trace elements?
A. Adding calcium carbonate is a safe way to prevent calcium deficiencies (provided vitamin D3 is also available) and the protein content of the diet is within safe limits for the species in question. You are correct, however, in pointing out it will not help with other potential mineral deficiencies. This is why in addition to daily use of calcium carbonate, we also use a general multi-mineral supplement. These contain many micro-nutritional elements that may otherwise not be present in a captive diet. Examples of such products include ‘Miner-All’ and ‘Nutrobal’. We use these a couple of times a week, and find that this does appear to be adequate to prevent such deficiencies. We increase frequency for juveniles and egg-laying females.
Q. I keep a Geochelone
sulcata (African spurred
tortoise) and I live in
A. You are fortunate to live in an area with a high concentration of sun-loving reptiles and many days a year of cloudless skies! Like your tortoise, they are successfully synthesizing their D3 requirements from the UV-B component of solar radiation. In your situation, we believe you have no need of any oral D3 supplementation. In you lived further north, or in a cloudy area, however, that situation would change. In such regions, at least some regular oral supplementation is highly advisable.
Q. Many books I have read suggest that I should use a vitamin-A supplement regularly? What do you think?
A. On a good diet, as suggested above, this is not necessary. Certainly, we do not advise use of ‘pure’ vitamin A or D supplements as there is a possibility of overdose with all of the fat-soluble vitamins if used in this manner.
Q. Can I use ‘liquid sunshine’ D3 drops instead of spending all that money on expensive UV-B lighting systems?
A. We absolutely do not recommend products like this. They are potentially very dangerous (see answer to vitamin-A question, above). Overdoses are very possible with ‘pure’ D3 products. Avoid them.
tortoises become overweight?
A. Yes, they can. Species which naturally have very short annual activity cycles, due to hibernation, estivation, or both are especially susceptible to problems of this nature resulting from the excess or ‘glut’ of food available in captivity. Species such as the Russian tortoise (Testudo horsfieldii) and Geochelone sulcata (African Spurred tortoise) are notoriously difficult in this regard. We have seen some truly obese examples. In fact any tortoise maintained on a really inappropriate diet will become overweight, and ultimately may suffer from fatty infiltration of the liver. Any diet that is high in saturated fat is almost guaranteed to produce this outcome in an herbivorous tortoise.
Useful links and further reading
On this website:
Understanding Reptile Lighting Systems - Covers choice of UV-B lamps
Dietary Constituents for Herbivorous Tortoises - Classic text and vital background reading
Vitamins and Minerals - An outline of these essential dietary elements and what functions they serve.
Promoting Proper Bone Development - Discussion of Calcium supplements.
Feeding Redfoot and Yellowfoot Tortoises - Detailed discussion of these tropical, omnivorous species and their diets in the wild and in captivity.
High Growth Rates and Vitamin D3 - Discussion of some interesting issues concerning shell deformities, D3 toxicity, etc.
Do Tortoises Need to Drink? - Find out here.
Feeding Aquatic Turtles - Discusses the very different needs of these species
Live Food Choices - For omnivorous turtles
When Tortoises Refuse to Feed - Identifying problems
Mediterranean Tortoise - How much to Feed? - Controlling diets
Dealing with Dietary Addictions - What to do if your tortoise is addicted to a bad diet or is a "fussy feeder"
Rearing Healthy Hatchlings - Diet and environment issues
"The Tortoise and Turtle Feeding Manual" By A. C. Highfield
Available from Carapace Press. The basis of this article and a highly comprehensive discussion of the many issues surrounding the nutritional management of captive tortoises and turtles. This book has received 5-star reviews and is highly recommended to all keepers.
Other recommended links and resources:
The T-Lady's Online Guide to Mediterranean Tortoise Care - Lots of excellent advice on growing and choosing "weeds" to provide a natural diet.
(c) A. C. Highfield (2002)