The following is a general care guide. While it does cover the main topics concerning the proper husbandry of Hermann's tortoises, it's important to know that there is much more to learn. This care guide is a wonderful source for getting started with this species but I highly recommend thoroughly researching this site and all it has to offer for a more in depth look into the world of Testudo hermanni.
To date there are two recognized and/or accepted subspecies after a recent attempt to elevate them to the rank of full species level(“Eurotestudo”, 2006) was temporarily rejected. This will most likely be revisited in years to come with a different result based on the high degree of differences between the currently recognized subspecies and even the localities found within them.
The western Hermann's tortoise (Testudo hermanni hermanni) is the nominate race with a type locality of Collobrieres, France. It is the rarest of Hermann’s tortoises both in nature and captivity. These animals typically attain smaller dimensions than their eastern cousins and appear more attractive as well. The ground color they exhibit is a rich golden yellow to bright greenish yellow bordered by jet black bars, bands or blotches usually covering more than 50% of the carapace (very light specimens occur in almost all localities with heavy concentration in certain origins). The yellow ground color and jet black markings of the carapace create a high degree of contrast especially noticeable when the tortoise is wet. A well-defined keyhole or “mushroom cloud” symbol is exhibited on the 5th vertebral scute just above the supracaudal shield and this has been present in more than 95% of the animals I have observed. The head is rather sleek with regular contours when compared to those of the other subspecies. A bright yellow, subocular fleck or spot is usually visible underneath and just behind each eye. This may be lacking in elderly specimens or tortoises from certain locales. The skin color resembles that of the carapace's ground color but may be a light grey-green. On the plastron there are two longitudinal jet black bands or stripes that are well formed and continuous along the midline. They are only occasionally, slightly broken, most commonly around the humeral scutes and anal scutes. The suture between the femoral scutes on the plastron is longer than that of the suture between the pectorals but in certain instances they can appear even. Rarely is the pectoral suture longer than the femoral. Inguinal scutes are usually present. Females rarely exceed six inches while some males may not surpass four; however larger examples are not uncommon. The western Hermann's tortoise is also known for typically being rounder and more domed in appearance when compared to the other subspecies. The highest point of the carapace is commonly situated somewhere between the second and fourth vertebral scute but this varies with locale and even within a given population. There are in fact several distinguishing characteristics (some rather blatant, others not so much) that set western Hermann’s tortoises from different localities apart. To the untrained eye, these may be less noticeable but to an experienced individual, they can really stand out in certain instances.
The eastern Hermann's tortoise (Testudo hermanni boettgeri) is the larger, common race. These tortoises are usually viewed as “dull” when compared their western counterparts with colors as well as markings varying extremely. Rather attractively colored specimens are not unheard of. In fact, we maintain some striking eastern tortoises ourselves. The ground color of the carapace is typically a horn color or can be brown, yellowish, or ochre. Less intense black or dark brown bars and blotches border it. The 5th vertebral scute usually lacks the keyhole symbol but a less defined “version” of it can found in some specimens especially captive bred juveniles. The head is bulkier with the eyes situated higher up and the yellow spot or fleck under each eye is usually absent except in neonates. Skin color is usually dark and may be tan, brown or grey. The plastron exhibits discontinuous black markings which appear faded, broken up and nowhere near as well defined or prominent as in their western cousins. However, an almost entirely black plastron is sometimes found in specimens deriving from southern Greece. The suture between the pectoral scutes is usually longer than that of the femorals or they may be an even length in various cases. Females typically reach seven to eight inches but extremely large, ten inch plus females have been encountered in parts of the world such as Bulgaria and also in captive collections. Males usually do not surpass seven inches but larger animals are not unheard of. These tortoises have a flatter, broader look and are more elongate than round.
A third, once accepted subspecies known as The Dalmatian tortoise (Testudo hermanni hercegovinensis) is still recognized by many keepers worldwide today. Recently, this tortoise has been discounted by taxonomists as a valid subspecies due to the lack of supporting evidence that they are in fact different from Testudo hermanni boettgeri. Instead, they are considered to be nothing more than a geographical variant of the eastern subspecies. For decades, tortoise enthusiasts were unaware of this potential third type of Hermann’s tortoise thus leading to the inevitable cross breeding of them with pure eastern specimens. The Dalmatian tortoise does exhibit some external differences that certainly set it apart from the western subspecies, but also differentiate it from the eastern to a degree. These animals are rather smallish. They resemble Testudo hermanni hermanni with regards to their size and may even be considered smaller at times due to the wide array of dimensions found within T. h. hermanni depending on the region they are found. Females of this variant of Hermann’s tortoise will rarely exceed 6” with males sometimes falling short of 5.5” (in Sardinia and Corsica, tortoises belonging to the western subspecies can easily surpass 8”, so you can see how the Dalmatian may at times be considered the smallest members of the T. hermanni species complex). The colors and markings of the Dalmatian are quite close to that of T. h. boettgeri but may be more defined. The plastral pigment can sometimes depict that of the stripes found on T. h. hermanni but instead are always discontinuous. The ratio between the pectoral scute suture and femoral scute suture is often even but may resemble the ratio found in either the western or eastern subspecies. The suture of the humeral scutes typically forms a sharp, downward curving “U”, but again, this may not always be the case and this is also found in a majority of western tortoises and some easterns. The head is rather rounded and blunt with a subocluar spot usually lacking except in younger specimens. Usually, yellow-green markings are found on the top of the head at the back. The supradcaudal shield may or may not be divided and inguinal scutes are lacking some 60% of the time. Some specimens will feature only one inguinal scute on either the right or left side. This is where differentiation can become difficult because although very rare, both T. h. boettgeri and T. h. hermanni have been encountered with inguinal scutes lacking entirely. In fact, on Sicily, western tortoises may be lacking only one. This is a trait that is less often seen in other western locales and combined with characteristics such as the presence of thigh tubercles (like those found on Testudo graeca), the discovery and addition of a new subspecies of Hermann’s tortoise may surface in years to come. A fourth subspecies has already been proposed but has since failed to gain any real acceptance. Small eastern tortoises found in the Peloponnesus (southern Greece) have been labeled “Testudo hermanni pelponnesica” but they have not graduated from just a geographical variant yet. A complete revision of the taxonomy concerning the Testudo hermanni species group is needed because at present, only two subspecies are valid and this raises great concerns for the captive breeding and also head-starting of juveniles into nature. Hermann’s tortoises vary quite heavily from region to region and even within a select population. It is imperative that we gain a better understanding of not only the morphological differences that set them apart but also behavioral and perhaps even biogeomorphology specifics as well.
Hermann’s tortoises are found throughout southern Europe. Mediterranean oak and beech forest, scrubland, rocky hillsides, meadows and other areas with dense vegetation and calcium rich soil are suitable habitat for wild Testudo hermanni. Yugoslavia, Albania, Romania, Bosnia, Croatia, Greece, Montenegro and Bulgaria are all inhabited by the eastern strains while the western strains are restricted to mainland Italy (including Sicily and Sardinia), the south of France (including Corisica) and northern Spain (along with the Balearic islands Mallorca and Menorca).
Eastern Hermann’s tortoises (T. h. boettgeri) are readily available in the USA. Keepers have been successfully breeding this subspecies for decades now and captive born hatchlings are almost always attainable. Typically, hatchlings can be found for sale easily in late summer into fall when eggs laid in spring have hatched. Reptile expos and online sources will offer eastern Hermann’s tortoises throughout the year of various ages for reasonable prices. Every year wild collected and farmed specimens are imported into America from Europe. These specimens are often riddled with parasites and may be harboring infectious diseases. It is best to stay away from these and aim to purchase captive bred tortoises only. Western Hermann’s tortoises (T. h. hermanni) on the other hand, are rare in USA collections. They have never been heavily imported into the country which is attributed to their endangered status in nature and few have been fortunate enough to breed actual pure stock. Those that are produced fetch high prices.
Size varies with Hermann’s tortoises. Typically, the eastern subspecies tops out between 6” for males and 8” for females (4.5-6” for the Dalmatian variant). Smaller examples from areas like southern Greece and huge specimens (9 to 11”) from places like Bulgaria are not rare. For the western subspecies, males may not grow larger than 4 to 4.5” and females may not surpass 6” max. Again, smaller tortoises (Mt. Etna for example) and larger individuals (Corsica and Sardinia) exist. Some Sardinian and Corse T. h. hermanni may reach impressive dimensions of more than 8”. Regardless of subspecies, males are the smaller of the sexes. In some cases they may appear to be nearly half the size of an adult female when fully grown depending on origin.
Hatchling Testudo hermanni are suitable for indoor keeping and by choosing this method in the beginning we are protecting them from harsh elements and possible predation. Outdoor keeping at this stage of life does work well but can pose problems especially for an inexperienced keeper. We have managed to successfully house neonates and juveniles in both outdoor and indoor settings but you may find it more comforting and easier to monitor them if indoor housing is your method of choice. Never use glass aquariums for tortoises. They create a constant “greenhouse” effect inside causing them to rapidly dehydrate. They also drive the tortoises crazy because they cannot comprehend what glass is and why they can see through it but not move forward. This sends stress levels through the roof. Use Rubbermaid containers instead or “tortoise tables” built from ply wood. For 2 to 3 hatchlings, a container roughly 2x3 feet will suffice. It should be at least 6” tall. Do not go too big while they are so small because they may become “lost” in the environment and you will find yourself constantly digging around to find them. As the T. hermanni grow, the size of the container can be increased to accommodate them. Several neonates can be raised together without issue if space permits but watch out for any weaker individuals who may have trouble competing for food. A suitable substrate is clean top soil mixed with coconut coir or peat moss. I prefer to ad sand into this mix to help generate a substrate that replicates what they experience in nature more closely. However, using sand has been known to cause impaction in reptiles which can lead to death. Although in more than 20 years we have never experienced this with any of our tortoises kept on it, this does not mean it won’t happen to your animal(s). Use caution or simply don’t use the sand. The substrate can be up to 4” deep to allow for burrowing. Burrowing is 100% normal! Do not be alarmed by his behavior while they are this young. They are babies after all and babies sleep. I also recommend adding cypress mulch as a 2” top layer but you can also mix it in to the existing substrate. The mulch aids in keeping an adequate humidity level which should be around 70%. Do not let the substrate dry out entirely by keeping a spray bottle filled with water on hand to mist the enclosure. A common misconception regarding tortoise keeping is thinking they must be kept very dry. This is in fact not true and we now know that pyramiding (unnatural, lumpy growth of the carapace scutes)is directly linked to improper humidity levels along with insufficient hydration. In nature, baby tortoises spend a great deal of time burrowed into the ground, under leaf litter or jammed under debris. There, it is humid, moist and dark. They are programmed to hide and typically do not venture out anywhere near as much as older specimens. By doing this they are constantly subjected to a higher level of humidity than one might assume. Although wild tortoises can sometimes appear lumpy or pyramided, this is only in extreme cases where severe droughts are common. Most will exhibit beautiful growth and smooth shells. In the evening after the lights are turned off, I place the lid on the rubbermaid containers that house our baby tortoises. This helps to mimic the dark, humid refuges the neonates confide in when in nature. The humidity builds up overnight and in the morning it is released when the lids are taken off. I do not doubt for one second that this method has something to do with the natural, smooth shells our tortoises attain as they grow.
A very shallow water tray (0.5”) can also be provided to the babies so that they have constant access to fresh water. Drinking is crucial for baby Hermann’s tortoises and additional soaks for 15 minutes in luke warm water, 3 to 4 times weekly are also wise. Half logs, upside down tupperware with an entrance hole cut in, drift wood and cork bark make for excellent hide aways. These will be used frequently by the occupants. Fake plants or edible weeds may be grown in the indoor unit if you wish to do so. I opt against it for the sake of simplicity and cleanliness because we are dealing with a high number of animals. The use of plants absolutely does not “make” or “break” the enclosure for us especially since our tortoise spend a great portion of the year outdoors in very natural conditions. Just like indoors, they should always have access to fresh water. The 2” deep stainless steel dishes mentioned above work great outside too and can easily be cleaned. The adults will use them frequently to soak in and drink from but they will be soiled quickly. Mosquitoes will use them as a perfect breeding ground so be ready to change them often.
Housing larger juveniles and adults indoors is possible especially during the winter. By using the “tortoise table” method, an 8x4 foot rectangular enclosure out of ply wood can easily be constructed. This will house a trio of adult tortoises in the 4 to 6” range for part of the year but as always, going as big as possible is best. Aggressive animals must be watched closely. Even female Hermann’s tortoises can inflict wounds on one another especially if they are carrying eggs and fighting for a nesting area. Males may naturally engage in combat but be ready to separate them if it gets out of hand. It is part of the natural daily cycle for members of the Testudo hermanni species complex to encounter others of their own kind. While tortoises do not suffer from loneliness or experience emotions, it is stimulating and nothing less than natural for them to be subjected to other members of their species/subspecies. However, it is always wise to have extra enclosures ready to house aggressors to prevent serious damage to the other conspecifics. Cypress mulch 4 to 6” deep works best for adults but you can also use the same combo that I described above for hatchlings. Large pieces of cork bark or drift wood make for excellent decor inside the enclosure. Larger rubbermaid containers turned upside down with an entrance hole cut into it can be made into a “humid hide” for younger Hermann’s tortoises to help keep up with smooth shell growth. The container can be filled with moistened sphagnum moss. Change the moss frequently because it can become a breeding ground for harmful bacteria. For full sized adults, I prefer to use straw inside any hide-box given to them. It is not as messy and allows the adults access to a cozy, dry refuge. A stainless steel water dish no more than 2” deep should be set into the cypress mulch so that the animals always have fresh water to drink and soak in. This must be changed frequently because the tortoises will defecate in it often. Even for larger T. hermanni, hydration is crucial for long term success. This is especially evident with the western subspecies which seems to “dry out” and become dehydrated quicker than their eastern counterparts.
Hermann’s tortoises undoubtedly do best outdoors and they can be kept in this manner from at least April until October in most parts of the USA. A strong outdoor enclosure placed in a sunny location can be constructed out of pressure treated wood, stone wall or landscaping timbers. For a group of 2 males and 6 females, the unit should measure at least 12x8 feet with a height of 18”. A graciously planted outdoor pen situated on well-drained soil makes for a great captive environment for these tortoises. I recommend removing the existing soil especially if it does not drain well. Replacing it with a mix of clean top soil, pit gravel and sand makes for a nice, naturalistic terrain for the occupants. Be creative with the terrain and rather than leaving it flat, allow sloping areas, and uneven spots with higher ground. Although Hermann's tortoises prefer a bit more humidity in their environment than most other Testudo, they should never be subjected to consistent damp situations. A variety of planted, edible weeds to promote natural grazing is suggested as well as an array of decorations like logs, rocks, slates, shrubs, African grasses and bushes, for exercise, hiding and burrowing. Some excellent plant choices are spirea, hosta, knockout rose, hibiscus, fountain grass, maiden grass, sedum, yarrow and Mediterranean heather. Make sure to keep tortoises well protected from predators such as raccoons and theft. A framed lid out of 2x3’s equipped with a thick wire mesh should cover most or all of the outdoor enclosure to keep invaders out. Set on hinges the lid or lids can easily be opened and closed. I recommend using locking latches to further prevent potential theft.
In areas where weather isn’t very reliable, I recommend using cold frames or mini greenhouses for the tortoises to enter. These can be ordered online and are relatively inexpensive. I situate them onto a base that is slightly sunken into the ground. An entrance is made for the animals and inside, a thick bed of straw is available. Testudo hermanni really make use of these green houses as they seek the warmth inside them on days when temperatures are not optimal. I have even noticed that nesting females will choose to dig their nests and deposit their eggs inside them. A heat lamp with a 250 watt infrared bulb can be installed inside them for even cooler days/nights. I’ve also had a great deal of success when using small dog houses or hutches filled with straw as shelters. The tortoises seem to find them very comfortable and will choose them over the greenhouses on very hot days.
Some Words on Lighting, Temperature & Humidty
Absolutely nothing beats natural sunlight especially when it comes to tortoises such as Hermann’s. These animals occur in “warm spots or islands” within their native range. In these places, sunlight is plentiful and strong thus providing the animals with adequate UVB. This is why it is so important to place the outdoor enclosure in the sunniest location of the yard. For indoor lighting, a 10.0 UVB emitting fluorescent bulb should be fixed across the top of the enclosure. A 50-75 (hatchlings & juveniles) or 100-150 (adults) watt basking light should also be placed at one end only to offer the tortoises a basking site of between 90 and 95F. Up to 105 is ok for adults only. Depending on the size of the enclosure, you may want to use more than one basking light to offer the tortoises multiple basking areas but be sure the occupants always have an area where they can escape the direct light and heat. They may however not use the basking area too frequently if they are newborns. Remember, they know they are vulnerable and instinct tells them to hide as much as possible. The tortoises should be subjected to 12-14 hours of light each day regardless of age. Humidity is crucial in properly housing Hermann’s tortoises long term. Dehydration is a real threat especially in artificial conditions. A humidity level of around 70% is needed and this can be achieved by offering the tortoises a proper substrate, a constant supply of fresh water and regular, light mistings with a spray bottle. T. hermanni of all ages ages will appreciate a “fake rain” through means of misting or spraying them down. They will walk with their bodies held high, extend their heads and necks into the “rain” and drink from little puddles or from the beads of water that form on the walls of the enclosure. Ambient room temperature should hover around 80-85F during the day and can be allowed to drop into the low 70s at night. T. hermanni are capable of withstanding much cooler nighttime temperatures but if they are very young, it’s wise to not let it drop that low just yet. Additional heat sources like heat pads or rocks are terrible for tortoises and should never be used. Another common misconception is when keepers panic and feel that their “babies” need additional heat at night. This is how heat rocks and pads end up being used and how tortoises can die from them. It’s a “no brainer” to know that the indoor set up should not be near a drafty area such as window or in a cold room.
LET THEM BE.
Do not pamper these animals, there is simply no need for it and overdoing things can actually cause harm. These are wild animals no matter how many times we produce them in captivity. They do not “like” or “love” us, and it is important for us as responsible keepers to accept and understand this. They need little interference from us if set up correctly from the start. On another note, it should not go with out saying that Hermann’s tortoises, although shy in nature, can prove to be quite outgoing and responsive in captivity. They quickly associate their keepers as a source of food and lose there fear of us. Some will even allow a scratch on the top of the head. However, like all turtle and tortoise species, T. hermanni do not like to be handled. Handling a tortoise, an animal that is so close to ground by nature, only causes unnecessary stress and long term problems. Your tortoise should only be picked up when absolutely necessary especially when they are so small and young. They will always be wild at heart.
Low protein, high fiber and calcium rich are crucial points to keeping Hermann’s tortoises stable and healthy. In nature, much of their day is comprised of grazing or browsing for edible vegetation. Unfortunately, many uninformed keepers turn to supermarket produce which is generally lacking in acceptable fiber levels and is too high in sugar. A diet rich in protein will eventually cause renal failure and offering too much fruit will bring on diarrhea or even an outbreak of internal parasites. Pesticide-free weeds grown in the yard such as dandelion, clover, plantain, catsear, thistle and vetch make for excellent food items. Mulberry leaves are also recommended. Here, we make sure our tortoises get Mazuri tortoise diet (original formula) several times a week. This commercial diet aids in keeping a healthy weight on the animals, enables hatchlings to grow steadily and rapidly replenishes nutrients lost in females who have recently deposited eggs. For years we have raised many species of tortoise by using this diet in combination with appropriate weeds and the outcome is more than satisfactory. Sometimes, supermarket produce may be your only option. Whenever possible, purchase only organic greens and stay away from all lettuces. Collard greens, romaine lettuce, mustard greens, radicchio, endive and turnip greens will suffice in moderation. Various “tortoise seed mixes” are now available from distributors and while these can make for an excellent variety of safely grown edibles, be extremely careful with them. Reports of tortoises becoming poisoned from these mixes are now beginning to surface. This may be attributed to the accidental presence of seeds from poisonous plants being mixed into the mix. Doing your homework in order to gain the knowledge of how to properly identify poisonous plants goes a long way. Google is at everyone’s fingertips now so start researching, it could save your tortoise’s life.
For calcium intake, I choose to not force it on the tortoises. The all too familiar practice of dusting each meal with calcium powder can cause long term problems down the road. Instead, a constant supply of cuttle-bone is kept in every enclosure with tortoises of all ages. The animals will nibble the bone as they feel the need. Adults, particularly females, will use the cuttle bone more often than males or neonates. Only occasionally will we dust the food items with powder. In the case of growing youngsters and gravid females we may do this twice monthly. Phosphorus free calcium powder and cuttle-bone can be purchased at most pet stores or in bulk online.
In the wild, Hermann’s tortoises wake up from their winter rest anywhere from March through May (depending on region) and nesting occurs from May through July. Males reach a peak in sexual activity immediately following emergence from their hibernaculums and again several weeks prior to cooling down for the winter ahead of them. When engaging in courtship, the male rams and chases the female relentlessly biting at her legs and face. Once the female cooperates, successful copulation occurs. During copulation the male emits several high pitched squeaks and holds his mouth open while extending his tongue.
Gravid females become aggressive and extremely restless when they are nearing oviposition. They will continuously bite, ram and mount other females in their way. They will even gape their mouths and “squeak” just like males do during copulation. For days and even up to two weeks, they will continuously pace the perimeter of their enclosure in search of a proper nesting site. Females of the eastern subspecies seem to prefer open, south facing slopes with well-drained soil to deposit their eggs while females of the western subspecies may select a less conspicuous site such as under a grass or shrub, or in a corner. Females may dig several test holes in the days prior to the actual event. Females typically lay four to six eggs (T. h. boettgeri) or one to three eggs (T. h. hermanni) in a single clutch. Females of both subspecies have been known to double and even triple clutch in one season with anywhere from fourteen to thirty days in between nests. Some of our western Hermann’s will even lay up to four clutches in a season. Fertility varies and we have found this to be determined by the number of males, at least in our care. Males will fight one another and this is a healthy part of tortoise breeding behavior. Keepers are sometimes all too quick to keep few males or house males completely separate from one another. While it is crucial to hold a watchful eye on them, it is only normal for them to encounter conspecifics of the same sex several times in a season. The competition of another male enables stimulation and helps to lessen the chances of “boredom”. Single males can certainly get the job done for a while but I truly feel that one of the keys to very long term breeding success with any Testudo is to have more than one male. There’s no reason to be “female greedy” if you don’t have enough “bull males” to do the job. A lone male is sure to “burn out”, become bored and disinterested in due time. This can take 10 years or can happen in as little as 3. Depending on how many females you have in a group will determine how many boys you can handle. Keeping extra enclosures or pens is a common practice for us here so we can accommodate multiple males, especially since they will cause issues if left together or with the females for too long. In nature, tortoises see each other all the time. It’s nothing less than natural and certainly has its benefits. They of course do not get lonely or need companionship to any extent but it is only fair for them to experience at least some degree of what they encounter in nature. This includes the presence of other tortoises, even the same sex. Not all of us have intentions of going full time with tortoise breeding, in fact some of us never wish to breed tortoises at all. Those of us that do hold a special responsibility to provide them with the best care we can give. This should not be restricted to enclosure types, substrate, lighting, temperature, etc…but should include offering them mental and behavioral care as well. For individuals who house tortoises strictly as pets or for enjoyment, it is imperative that you watch your animals closely if you have more than one. “Bullying” is a common problem that can occur when raising tortoises and the weaker animal will lose feeding rights, deteriorate in health and eventually die. Whether they are males or females, have extra enclosures ready to go in case an issue begins.
Here, like all tortoise species we breed, the eggs are carefully dug up and placed into artificial incubation. Deli containers with a few small holes punched into the sides or lid are filled with dry vermiculite. The eggs are then put on the vermiculite in little depressions made by first pressing a finger down. Once set in place, they should not be moved or turned. The containers are placed inside an incubator of choice and set at between 84 and 91F. During the incubation period the eggs are only lightly misted with warm water occasionally. A bowl or two of water is maintained inside the incubator at all times to help achieve a desired humidity level of 70%. It’s important that the vermiculite does not stay damp for extended periods because the eggs of Hermann’s tortoises (particularly Testudo hermanni hermanni) are highly susceptible to cracking or splitting caused by moisture. This is the reason for placing them on dry vermiculite. At the end of the expected period, the eggs are lightly misted to replicate fall rains which hatching is usually timed with in nature. At between 53 and 70 days the tiny neonates begin to pip and emerge from their eggs. They are left in the containers inside the incubator until they straighten out and absorb the remnants of the yolk sac. Then they are soaked and placed in the hatchling rearing units.
Hermann’s tortoises are temperature sex dependent in that the sex of the neonates can be manipulated by forcing the incubation temperature in a certain direction. The higher the temperature will result in females and the lower in males. It’s worth mentioning some specifics regarding incubation temperatures pertaining to the particular subspecies of Hermann’s tortoise you’re working with.
For the most part, the eggs of Testudo hermanni hermanni can be subjected to higher temperatures in order to really produce females. While some reports state that they can go as high as 92.5F to ensure female production, I feel it is not necessary to surpass 90-91F. To be safe, keeping the eggs between 89.6 and 90F seems to result in normally formed babies that are in fact female. Any higher and anomalies (extra or split scutes and other deformities) are inevitable along with possible embryonic failure. For this subspecies, a highly reliable and precise incubator should be used in order to really monitor temperature fluctuation. Fully formed babies can die within the egg if the temperature climbs just a little too much when they are already at a relatively high degree. If you are not concerned with the end result being all or mostly female, then a safe degree would be the 86-88F range. Incubation methods and temperature can even vary from locale to locale. For example, in our care, the eggs belonging to T. h. hermanni from Majorca (Mallorca) are sensitive to both heat and dampness more than other western Hermann’s tortoise strains. They must be kept very dry with little misting, even right before hatching or the eggs may crack and the neonates may drown. Pushing the temperature any higher than 89.6F will surely result in anomalies with embryonic failure being commonplace at any stage of the incubation period. These requirements for the eggs of tortoises from this Balearic island may be attributed to the consistency they are subjected to in nature. Dry, mild temperatures make up the climate on Mallorca with August being the hottest month. Even so, “hot” does not mean 90s or 100s on this island. Mid to high 80s is more typical. These are merely assumptions based on the Mallorcan tortoises bred here as we searched to find a reason behind the lack of success in hatching eggs that were kept at the same temperatures as other Testudo hermanni hermanni. Once temperatures were lowered and the eggs were kept on the drier side, hatching success began. Of course relative humidity of 70% was still maintained via water bowls near the incubating eggs.
For Testudo hermanni boettgeri, temperatures any lower than 87F seem to result in all male usually, while any higher than 89.6F will reveal hatchlings that exhibit severely split scutes of the carapace. For the Dalmatian tortoise, females can be produced at as low as 87.5F. Embryonic failure rapidly takes place when temperature surpasses 88F in some cases.
These ranges are based solely on Hermann’s tortoise breeding and incubation taking place at my facility and on reports from other keepers alike. They do not represent the entire world’s view on the subject and success varies from situation to situation based on a variety of factors and/or methods.
Hermann’s tortoises brumate in nature as a way to deal with unfavorable conditions during the cold part of the year. The length of this is decided based on the extent of the winter they experience in a particular geographical range. While some populations of T. hermanni brave long, cold winters with abundant snow fall (eastern specimens found in the Macedonian mountains for example), others experience short winters with mild temperatures (western tortoises occurring in areas like Sicily and Mallorca to name a few). In captivity, we constantly struggle with the decision to provide our tortoises with a brumation or cooling period or to not. In today’s literature it is not yet really proven that brumation will keep tortoises healthier longer or aid in the fertility rate of eggs or breeding activity as a whole. There are many theories pertaining to this subject which can be read online and in the forums of this site. Many of us have taken matters into our own hands, choosing our own methods through trial and error to see what really works for ourselves and the tortoises. Hermann’s can be successfully brumated both indoors or outdoors depending on where we live. In the north east, I have had success brumating T. hermanni ssp. outdoors naturally and under artificial indoor conditions (crawl space for example). Indoors, the refrigerator, crawl space and basement methods have proven to be successful and so has loosening the ground in the outdoor enclosure, allowing them to dig down as they experience the change in season. The use of cold frames or greenhouses in the outdoor enclosure will help to minimize stress and offer the tortoises appropriate conditions for winding down as winter approaches. The tortoises must stay at temperatures in the low 40s to prevent them from awakening too early but we must make sure they do not freeze. In more than 20 years of working with these animals we have not seen a decrease in breeding behavior or fertility when we have not allowed our tortoises to brumate, however, that is still a short amount of time in the grand scheme of things. Brumation is something they naturally do and we practice that here. Choose wisely and follow methods that have worked well for experienced parties but always remember, we are all still learning no matter how long we’ve been doing this. I don't consider myself an expert, I’m merely a student learning from the tortoises themselves.
For a more extensive read on brumation, follow this link to an article I wrote on the subject: BRUMATION