Authored by Chris Leone Garden State Tortoise
Hermann’s Tortoise Reproduction and Breeding
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 or no misting at all, even right before hatching or the eggs will surely 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 completely dry, 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 hibernate 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 hibernation or cooling period or to not.
In today’s literature it is not yet really proven that hibernation 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 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 hibernated both indoors or outdoors depending on where we live. In the north-east, I have had success hibernating T. hermanni boettgeri & “hercegovinensis” in both situations and T. h. hermanni in artificial indoor conditions (refrigeration for example). Indoors, the refrigerator method has 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 do not allow our tortoises to hibernate. 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.
This is part 3 of Hermann’s Tortoise click the link to see part 2 Hermann’s Tortoise Captive Care
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