How to keep...

Tortoises

Peter Bulsing

INTRODUCTION

I was asked by the editors of Pod@rcis to contribute an article on tortoises to their 'How to keep...' series. This turned out to be as complicated as actually keeping and caring for these special cold-blooded animals.

Over forty of the approximately 260 species of turtles live exclusively on land. The remainder, to varying degrees, depend on water. Terrestrial turtles, or tortoises, form a relatively small group. This may lead one to believe that there is little difference between the care in captivity of the various species. This is far from the truth. Their environmental demands and requirements for the decoration of their cages may vary widely. It is also impossible to give generalised advice concerning their diet. In this paper I will attempt to point novice tortoise keepers and other interested people in the right direction.

CHOICE OF SPECIES

First, let me make clear that a tortoise is not an animal that should be brought home impulsively, especially considering their long life expectancy. Amateur breeders offer such a supply of animals that there is ample opportunity to carefully consider your options. Of course, any impulse purchase of an animal is always a bad idea!

If somebody decides to keep tortoises, the first question they should ask themselves is 'which species do I choose?' The answer should be carefully considered for an extended period of time. What can you offer the animals: an outdoor terrarium, an indoor terrarium, or perhaps a combination of both? Maybe you have an entire room available, or perhaps even a large barn? 

In the maritime climate of the Netherlands, few species are suited to an outdoor terrarium. Only the following tortoises can be successfully kept outdoors:

• . Testudo hermanni ssp.

• Testudo marginata ssp.

• Testudo (graeca) ibera ssp. - only the east European subspecies and geographical forms, and those from Asia Minor

• to a lesser degree - depending on the character of the terrarium (dry) - Testudo (Agrionemys) horsfieldii.

With the exception of Testudo (Agrionemys) horsfieldii, these are all 'Appendix I' animals, which means that keeping and caring for these species is illegal unless you possess a legal exemption. I will expand on this later (see 'Legal issues').

For all other tortoises an indoor terrarium is the only form of proper housing.

Combined housing, referred to earlier, entails that the tortoises are primarily kept in an indoor terrarium but on exceptionally beautiful days are allowed to walk around in an outdoor setting. Only stronger species and those that are not very susceptible to stress, such as Geochelone carbonaria, Geochelone sulcata and Geochelone pardalis, are suited to such conditions.

The size of the terrarium determines the size of the species or vice versa. To many aspiring tortoise keepers, it is tempting to select larger species. However, they do not fully understand that a pair of Geochelone pardalis requires a minimum floor space of 12 m²! For every additional animal, there is a considerable increase in required surface area. Geochelone sulcata, which I occasionally encounter in the commercial pet trade, requires even more space. Also bear in mind the enormous amounts of dung these giants produce. My advice is to contemplate before you start. Smaller species are not only easier to house, they are often a lot more active. This may considerably increase the pleasure that you get from keeping tortoises.

Clearly as important as the available space and the maximum size of the species is their hardiness. A large number of tortoise species are definitely not suited for novices. For example, all species of the genus Kinixys, Testudo kleinmanni, Malacochersus tornieri, Geochelone elegans and all North African subspecies and geographic forms of Testudo graeca ssp. are only suited for experienced tortoise keepers.

The species most suited for beginners is the eastern subspecies of Testudo hermanni, Testudo h. boettgeri. I indicated earlier that these animals could only be kept when one possesses a legal exemption. This does not have to be a problem. Many tortoise keepers breed them regularly, and offer these tortoises for sale with the corresponding papers. Addresses are available through the studbook of each species. Contact the Stichting Overkoepelend Orgaan Stamboeken (OOS) (http://www.studbooks.org) or the Nederlandse Schildpadden Vereniging (NSV) (http://www.igr.nl/users/nsv).

Commit yourself to one or a few species. Too diverse a collection can make your hobby uncontrollable.

HOW MANY ANIMALS?

Tortoises are basically solitary animals. People sometimes ask me, 'Could you take in my tortoise because its terrarium mate has just died and now it is lonely'. Too often we use our own requirements as a measure for our pets. A tortoise is generally just as happy alone, often even happier than with another animal or in a group.

In many species, the males are very assertive towards the females. They incessantly attempt to mate. In doing this, they ram and/or bite the female so often and so aggressively that damage to the shell and injuries to the legs and head are common. Apart from this visible damage, this assertive behaviour also leads to stress, which can reduce immunity against diseases and parasitic infections. Some species, such as Testudo hermanni ssp., Malacochersus tornieri, Geochelone elegans and Testudo kleinmanni, do well in pairs or small groups, although I still recommend housing the sexes separately. I consider this vitally important for successful breeding. Something else to keep in mind is that, almost invariably, males are extremely intolerant of each other.

Female tortoises of the same species are usually more tolerant of each other. Of course, the number of animals in a terrarium depends on the size of the terrarium. Keeping more than one species in the same terrarium is not advisable, even if only because each species has different requirements for its care and housing. Attempt to keep fewer animals, because having many tortoises in one terrarium makes the group more susceptible to diseases and parasites.

A warning to conclude this chapter: always keep juveniles separate from adult animals.

HOW DO I OBTAIN TORTOISES?

One can obtain tortoises from either the commercial or the tortoise enthusiast circle. Although very reliable commercial addresses exist, I would still advise you to look for the species of your choice within the circle of organised tortoise enthusiasts (OOS and NSV). There you can purchase legal animals with the highest level of certainty, and often at a lower price than in the commercial trade. It is also important that you receive good advice on the care of your animals and perhaps some guidance from a non-commercial breeder. Always bear in mind that when you purchase from a commercial broker, the possibility exists that you are buying wild-caught animals. While they may come with the corresponding papers, they still may be illegal. Knowledge on how to keep these animals is often hard to come by from these people. Many species of tortoise are being bred in captivity. For the sake of wild population preservation, buying wild-caught animals is not only undesirable it is absolutely unnecessary.

Many people prefer to obtain a large tortoise. Keep in mind that it can be very satisfying to see your tortoise grow to full maturity. With the proper care and some patience, every tortoise will eventually reach its maximum size.

Only purchase healthy looking animals (see 'Diseases').

SEXUAL DIMORPHISM

To the untrained eye, the gender of a tortoise can only be determined unmistakably in adult animals. Males are generally smaller and almost invariably have a longer tail and a concave plastron. However, this is not always the case, or not always clearly visible. For example, in Geochelone elephantopus ssp. the male is larger than the female, and in Testudo (Agrionemys) horsfieldii the plastron of both sexes is equally flat.

DECORATION OF THE TERRARIUM

Indoor terrarium

It is important to keep in mind while designing, constructing and decorating an indoor terrarium that it can be easily and properly cleaned. For this reason, make the maximum depth of the terrarium approximately one arm length. The floor surface and walls should be smooth or properly varnished so they can be disinfected easily. The front of the terrarium needs to be made out of glass. A vertical glass strip with sliding glass doors on top is preferable. Ensure that there is proper ventilation. If choosing plants, take note of potentially toxic species. Perhaps it is better, from a hygienic point of view, to opt for artificial plants. Whichever plants you choose, ensure they are out of reach of the tortoises inhabiting the terrarium.

For the remainder of the decorations, natural rocks and preserved wood can be very attractive.

As bottom substrate I recommend beech shavings or (repto) bark. These products absorb moisture very well and produce little to no odour. Using sand or soil is not advisable for most tortoises. There is a good chance that the animals will ingest soil while feeding. Beech shavings leave the animal's body partly digested. Soil, however, will accumulate in the intestines and may cause serious problems.

To prevent overheating, never place an indoor terrarium fully in direct sunlight.

Regardless of their age, tortoises enjoy a hiding place. The easiest solution is to provide them with a hiding box that is not too high and has an open front; this will suffice for virtually all species. If the animals are housed as a group (see 'how many animals'), several of such hiding boxes should be available inside the terrarium.

Very young tortoises need different decorations in their terrarium, and their climate control requires greater accuracy. We are dealing with species specific situations here. Consult a breeder or studbook keeper of the species in question about the requirements of a (rearing) terrarium.

Outdoor terrarium

A garden with a southern or western exposure is desirable for an outdoor terrarium. The enclosure needs to be as sunny as possible, although ample shade needs to be available as well. This can be created with small shrubs, such as lavender, alder berry or rosemary. It is recommended to place one or several small skylights in sunny locations inside the terrarium. These skylights can be placed on a low L- or U-shaped wall, or on poles, and are not meant to serve as a place for the tortoises to spend the night. Underneath these skylights, the temperature is almost invariably several degrees higher than the ambient temperature. The tortoises need to be able to freely walk in and out of these areas. In the spring, they can use these facilities to bask. If there is a pile of sand underneath the skylight, they may lay their eggs there later in the year.

The outdoor enclosure needs to be surrounded by walls with very little surface texture. The lack of texture will prevent the animals from climbing. The wall needs to be buried deep enough into the ground and be constructed high enough so that the animals can not climb and/or burrow out of their enclosure, even if the tortoises use each other as a jumping board. Construct a wide, horizontal ledge on the top of the walls and direct it inwards to make escaping almost impossible. If the species of your choice is a true burrower (such as Testudo (Agrionemys) horsfieldii) it may be wise to place a layer of metal screen approximately 35 cm beneath the ground level of the terrarium and attach it to the walls.

With some hardy plants, rocks and some different elevation levels, an outdoor terrarium can become a very pleasant location in your garden, both for the animals and the keeper. As a rule one should avoid contact between the tortoises and any toxic plants. Even though they rarely eat such plants, and they will normally not die from eating small amounts of a particular toxic plant, do not take any chances. With thick plastic foil, a bag of cement and some gravel it is relatively easy to construct a natural-looking shallow water basin, which will complete the decoration of your outdoor terrarium.

For hygienic reasons, and to prevent the tortoises from accidentally ingesting sand while feeding, the place where food is offered should be paved with tiles or a natural alternative like flagstones.

For the night, tortoises require a shelter that will protect them from cold, wind and predators. A small greenhouse with a recessed and paved floor filled in with garden mulch and a layer of reptobark (shredded pine bark) will suffice. A wooden night box filled with straw can be placed inside. Bear in mind that the temperature inside the greenhouse may rise to a dangerous level during the day. Therefore, proper ventilation and windows that can be opened are essential. In addition, it is important to provide the animals with two wide openings through which they can reach the outside section of the terrarium. It has happened before that a large tortoise blocked one exit, causing other animals inside to succumb to overheating

At night, the tortoises need to be locked inside their shelter to protect them from predators, especially rats and hedgehogs that may seriously injure or even kill the defenceless tortoises.

Cats, herons and crows can be a serious threat to juvenile tortoises, so only place full grown animals in an outdoor terrarium.

TERRARIUM LIGHTING

Indoor terrarium

Correct lighting inside the terrarium is crucial for the well-being of the animals. The question arises: what is correct lighting? Almost all species of tortoise live in more or less open habitats so that they often require a large amount of light. Geochelone denticulata and some geographic forms of Geochelone carbonaria will require less light, based on their natural forested habitat.

The amount of light and the amount of heat produced are both important when selecting the right light source. To determine the correct heat and light requirements for the animals selected, you will need to research the climate of the natural habitat of the corresponding species. You can find this information through a meteorological institute (such as the Dutch KNMI) or in the climate atlas (e.g. Handbuch ausgewählter Klima Stationen der Erde - Universität Trier).

For most species of tortoises it is important to supply an indoor terrarium with both a general light source and some spotlights. Fluorescent tubes are well-suited as the general light source. If you are concerned about the colour of the light, the Philips 'TL'D 965 Natural Daylight 6500 and the Osram Biolux produce excellent results. If you want your tubes to produce UV-B as well, then special tube lights for reptiles, such as the 'Arcadia D3 Reptile lamp' or the 'ESU-Reptile Daylight lamp', may be very useful. UV-B is necessary for the conversion of pro-vitamin D₃ into vitamin D₃, which enables the body to absorb calcium.

The aforementioned tube lights are available in the reptile trade. I wrote 'may be very useful' because it has been established that new tube lights produce the amount of UV light that is mentioned by the manufacturer or somewhat less, but it doesn't mention for how long. Normal fluorescent tubes do not produce UV light. Their regular glass construction blocks these wavelengths. UV radiation will only pass through quartz glass.

A spotlight produces a place to bask. Tortoises like to sit underneath it, especially in the morning, to increase their body temperature. Bear in mind when installing the lights that the animals do not burn themselves on the bulbs, and avoid any situation that may become a fire hazard.

The use of spotlights for very young animals is not recommended for many species. In my experience, the high temperature and the resulting drought directly underneath the light may cause malformation of the carapace (lumps may appear). Check with a breeder for the temperature requirements of your tortoise and how to supply it. A very important piece of advice: always perform these temperature measurements before using a terrarium!

Outdoor terrarium

In an outdoor terrarium, most species of tortoise require large amounts of light. The construction should be oriented to maximise the animal's exposure to the sun. A garden facing south or west is almost essential. Place one or several logs in the sun. This will give the tortoises an opportunity to bask diagonally facing the sun. Make sure that your animals do not use the logs to escape. Prevent overheating by creating generous amounts of shade.

FOOD AND MOISTURE REQUIREMENTS

Most adult tortoises are vegetarians, with a few omnivorous exceptions. For example, the diet of the tortoises in the genus Kinixys partly consists of snails, worms and insects. This does not mean that true herbivores will never take animal prey. In the wild, they will occasionally ingest a snail or an insect when eating a green leaf. There are even species that feed on carrion or dung. Those latter conditions do not need to be met in a terrarium.

I purposely mentioned adult tortoises in the first sentence. Juveniles of many vegetarian species will also eat insects, worms and snails in their early development. During this phase of their life they are very secretive; it protects them from predators and from overheating. Basking hardly takes place, eventhough this is so important for the production of vitamin D₃. It is suspected that, in nature, the animal portion of their diet supplies part of their vitamin and calcium requirements.

The previous paragraph brings me to the next topic. Apart from receiving a variety of food items, the animals need to be fed nutritional supplements with every meal, especially for animals kept indoors. The better supplements are Gistocal (available at speciality pet stores) or a combination of equal shares of Carmix and Sporavit (available through the NSV). Never supply more of these products than 2% of the total weight of the food offered. An excess of some vitamins can be as harmful as a deficiency. It is beneficial to add extra calcium to the nutritional supplements. This is especially important with fast growing juveniles and gravid females. Calcium carbonate is the preferred form of calcium that can be offered. This compound is available through pharmacies. Ground up eggshells or sepia (the inner shell of a squid) will do just fine.

Vary the food offered as much as possible, but always bear in mind the dietary demands of each species. Some will require more fibre in their diet (Geochelone pardalis, Geochelone sulcata), whereas others will need more fruit (Geochelone denticulata), or an occasional mushroom (genus Kinixys). Wash and dry the greens thoroughly before offering them to your animal(s). Never leave the food in the terrarium for more than a day.

Many tortoises love dry dog food soaked in cold water but it is rich in animal protein, which is not very good for them. As well, the phosphor/calcium ratio, which needs to be 1:2, is not attuned to a tortoise's diet. For these reasons it is advisable to add extra calcium when feeding dog food and to offer it sparingly.

Feeding frequency also deserves some attention. For most species, it is sufficient to feed them every other day. It would be too involved to discuss the specific demands of each individual species in this article. Part of the responsibility of every aspiring tortoise keeper is to obtain such information beforehand.

As a conclusion to this topic I have three warnings. Never feed your tortoise apple pits, avocados or too much sweet fruit. The first two are toxic and the latter is an excellent breeding ground for a parasite-related intestinal infection.

Every tortoise needs drinking water. Although much of the necessary liquid is extracted from food, and some animals may drink more than others, a bowl of fresh drinking water should always be present in the terrarium. Never place the bowl underneath or near a spotlight.

Some species prefer to lie in the water (Geochelone carbonaria and Geochelone elegans); bear this in mind when selecting a drinking bowl. Adding vitamin supplements to the drinking water is a waste of money. Most tortoises drink little and very sporadically. The vitamin and mineral supplements that are added to the regular food need to comply with the animal's demands.

HIBERNATION

Only the European tortoises and an occasional Asian species truly hibernate in nature (Testudo hermanni ssp., Testudo marginata ssp., Testudo (graeca) ibera complex (only the species Testudo ibera and the subspecies from Europe and Asia Minor) and Testudo (Agrionemys) horsfieldii. A few forms or subspecies of the North African Testudo (graeca) ibera go through a state of torpor throughout the winter but do not truly hibernate. All other tortoises do not cool down throughout the winter.

What is the difference between hibernation and torpor? When hibernating, the bodily functions are reduced to the bare minimum. Such a situation arises at temperatures between 2-5°C. Higher temperatures during hibernation can be harmful to the animal, as the body will use too much energy, which can be a big drain on their fat reserves. Never expose your animals to sub-zero temperatures. This will undoubtedly kill them. When in a state of torpor, the ambient temperature is somewhat higher than during hibernation. The animals are not sleeping, but are inactive and lack appetite. Such a situation is usually of short duration and does not need to be simulated in captivity.

Only healthy animals (see chapter on diseases) with a good body weight can be allowed to hibernate. The duration of hibernation for the aforementioned species is 4 to 5 months. Occasionally check the body weight and well-being of the tortoise. Do not transfer it to a warm environment, and make your check as quick and careful as possible. If the tortoise is losing weight too rapidly, or if there is mucus coming out of its nose, then allow the animal to slowly wake up over the course of a few days. At this point, you must decide whether a visit to a veterinarian seems necessary.

It is not always easy to find the right hibernation spot for your animals. The night shelter in an outdoor terrarium is only suitable when it is not too wet and its temperature remains above zero degrees. Sometimes basements are suitable. Fridges are also perfectly fine; the self-cleaning kind is preferable because the relative humidity inside remains higher. When using a fridge, the temperature can be accurately determined using a digital indoor/outdoor thermometer that can be placed on the outside of the appliance for ease of reading. Regardless of the selected hibernation spot, it is important that the relative humidity and the ventilation are carefully monitored on a continual basis. The relative humidity of the tortoise's direct environment should never be below 80%. This is easily checked with a simple hygrometer. Open the door of the fridge every day for a few seconds to refresh the air inside.

Tortoises should only be put through hibernation when they are properly prepared. The ambient temperature should be decreased gradually over the course of a few weeks, and you should stop offering food. Bathe the animals regularly in lukewarm water during this period. This will stimulate the animal's bowel movements and cause them to relieve themselves. If they don't empty their intestines after you stop feeding them, there is a good chance that during the hibernation period rotting excrement will cause internal problems or even death. Two weeks after you stop feeding your tortoises, turn out the lights. The animals will then become inactive. Subsequently, place them inside a chest or crate filled with dry leaves and/or straw on top of a layer of newspaper. Never use garden mulch, bark shavings, saw dust or hay! These products will easily develop fungal infections and/or contain a lot of dust. The latter will block the airways causing the tortoise to suffocate.

Ensure that the tortoises have decent ventilation.

At the end of hibernation slowly awaken your tortoises by gradually increasing the temperature over a period of several days. Once awake, put them back into a lukewarm bath. This not only activates their bodily functions, but also allows the animals to drink.

Sometimes tortoises refuse to eat after hibernating. A method that often helps is placing the animals in a warm environment (25-30°C) and giving them a lot of light. If this method is not successful, quickly take them to a veterinarian (see also 'diseases').

If, after reading the previous paragraphs, you are afraid to put your tortoises through hibernation then please don't do it. It is not vital for their well-being or for reproduction of the animals. Just keep them warm and awake.

There are also some species that 'hibernate', or aestivate as the proper term is, during the summer. This can be simulated under terrarium conditions. It is a situation that is comparable to true hibernation, but this time a high ambient temperature and drought trigger it.

Disturb hibernating tortoises as little as possible!

BREEDING

Tortoises produce hard-shelled eggs. Virtually all species excavate a nesting cavity. Exceptions to this rule are Manouria emys and Malacochersus tornieri. The former species constructs a mound of leaves and deposits the eggs inside; the latter sometimes lays its eggs in a rock crevice.

In captivity, eggs need to be removed immediately after being laid and the top of each egg should be marked with a soft lead pencil. Do not use any ink-based markers (such as felt pens). The ink will permeate through the porous eggshell and damage the contents. Next, transfer the eggs to a plastic box with small holes for ventilation. Fill the box halfway with moist vermiculite, and place the eggs inside with the pencil mark on top. Subsequently, transfer the box to an incubator for reptile eggs. Unlike in birds, rotating a reptile egg will damage the fetus. Marking the top of each egg can prevent this. The incubation temperature determines the sex of the offspring. With increasing temperature, the chance of female offspring increases.

It is impossible to offer general breeding advice, especially since one needs to bear in mind species specific conditions. Clutch size, number of clutches produced per year, incubation period and method of incubating the eggs all differ between species. It would be far beyond the scope of this article to get into more detail here. If you are planning to breed tortoises, contact experienced breeders or the OOS.

DISEASES

It is important to discover in time whether your tortoise is ill. Diagnosis and choice of medication are basically up to a veterinarian. Consult a veterinarian who is knowledgeable about reptiles. The web sites of POD@RCIS and the NSV supply a list of (Dutch) specialists.

How do you recognise a healthy tortoise? The animal should have:

healthy appetite

solid faeces

clear, clean eyes that are not recessed into the head

'dry', soundless breathing

clean nose

bright pink mouth

undamaged skin

relatively active disposition (depending on the species)

An animal that does not have these characteristics or is apathetic or extremely shy deserves the attention of a specialised veterinarian.

Tortoises are generally susceptible to worm infections. It is highly recommended to have a lab technician check the animal's faeces regularly (for example at The Missing Link in Rhoon for those residing in Holland, tel. 010 - 5014627).

LEGAL ISSUES

Dutch law prohibits the import and possession of many species of tortoise. This can be found in the Endangered Exotic Animal and Plant Species law (BUDEP law). The European and North African species (Testudo hermanni ssp., Testudo (graeca) ibera ssp., Testudo marginata ssp. and Testudo kleinmanni) are among the most strictly protected. To keep these animals you will need a governmental exemption on the prohibition of possession. If you are considering the purchase of a tortoise, check with the pertaining government office (CITES-agency) about the regulations with which both you and the retailer need to comply before making the actual purchase.

An impulsive purchase at an animal show brings with it the risk that, because of a lack of proper research into the pertaining laws, you unknowingly break the law. Ignorance is never accepted as a valid excuse by the government. Breaking the BUDEP law is punishable by a large fine and/or time in jail, so please be warned.

Laws change frequently. If I were to inform you here of the current laws, chances are that these will be altered shortly after publication. Therefore I advise you once more to contact your local CITES-agency and request an excerpt of the most recent version of the BUDEP law before purchasing a tortoise. Telephone numbers are available through the Dutch Ministry of Landbouw, Natuurbeheer en Visserij in The Hague (http://www.minlnv.nl/).

IN CONCLUSION

Contrary to what some animal protection organisations claim, tortoises can be very attractive and happy pets if cared for seriously and housed properly. They are bred in large enough numbers that breeders can satisfy the demand of other potential tortoise enthusiasts. True tortoise lovers are therefore not consumers, but quite the opposite, some have actually contributed to the protection and conservation of wild populations with their knowledge and captive offspring.

I detest the fumbling and dragging around that often happens with these animals. Exotic or not, living creatures are not toys or disposable items. Animals require serious care.

Not all pets are suitable for everyone. The number of allergy patients is increasing steadily in our time. For these people, reptiles can be an excellent alternative to animals with feathers or fur. However, a choice should always be based primarily on true interest!

In conclusion, I have one final warning. Caring for tortoises is very time consuming. In addition, these animals need to be fed in the morning before you go to work. Depending on their life span, you will be tied down for a very long time to the labour-intensive care of these unique animals. Make sure that this is properly considered when deciding whether or not to purchase a tortoise.

I wish you wisdom and success.