Tortoises are cold-blooded reptiles whose metabolism is directly influenced by the environment. When temperatures drop and daylight hours shorten, many tortoise species enter a state of dormancy that allows them to survive periods of cold and food scarcity. While this process is often mistakenly called hibernation, the correct scientific term for this reptilian dormancy is brumation. The decision of whether to allow your tortoise to enter this state depends entirely on its species and your ability to manage the process safely.
Clarifying Brumation and Species Differences
Brumation differs significantly from the true hibernation practiced by mammals. Mammalian hibernation is a deep, continuous sleep where the animal’s metabolism virtually shuts down, relying on stored fat reserves. In contrast, brumation is a state of metabolic slowing and lethargy triggered by low temperatures and reduced light cycles.
A brumating tortoise is not in a deep sleep; it remains somewhat aware and can wake up briefly to drink water or reposition itself. Environmental control during dormancy is important for tortoises due to this difference. Not all species are meant to brumate, and forcing the process on the wrong tortoise can be fatal.
Species native to temperate zones, particularly the Mediterranean region, are biologically programmed to brumate and often benefit from the process for hormonal and reproductive health. These species include the Hermann’s tortoise (Testudo hermanni), the Russian tortoise (Testudo horsfieldii), and the Greek tortoise (Testudo graeca). Conversely, tropical species like the African spurred tortoise (Sulcata) or the Red-footed tortoise (Chelonoidis carbonaria) should never be allowed to brumate because their bodies are not adapted to cold temperatures.
Essential Preparation for Safe Brumation
Preparation is essential for ensuring a tortoise survives dormancy. Weeks before brumation, a reptile veterinarian should perform a health check, including parasite screening. A tortoise with an underlying illness or one that is underweight should be kept awake and warm throughout the winter, a practice known as “overwintering.”
The most critical preparatory phase is fasting, which must occur while the tortoise is still warm and active. Food should be withheld for two to six weeks, with the duration depending on the tortoise’s size and species. This fasting is necessary to ensure the digestive tract is completely empty before its metabolism slows down. Food left in the gut when temperatures drop will rot, leading to fatal bacterial infections or gas buildup.
Throughout fasting, the tortoise must be soaked daily in shallow, lukewarm water for 15 to 30 minutes to encourage waste elimination and maintain hydration. It is essential to begin a weight tracking regimen, noting the tortoise’s weight daily or every few days. This pre-brumation weight serves as the baseline for monitoring health during dormancy, as a healthy tortoise loses minimal weight during the process.
Managing the Brumation Period
Once fasting and the “wind-down” period (where light and heat are gradually reduced) are complete, the tortoise is ready for its controlled environment. The temperature must be maintained within a precise and stable range, the most challenging aspect of captive brumation. The recommended temperature range is between 4°C and 10°C (39°F and 50°F), with an ideal temperature around 5°C (41°F).
Temperatures that fall below 3°C risk freezing the tortoise, while temperatures rising above 10°C will cause the tortoise’s metabolism to speed up. This elevated metabolic rate will prematurely burn through the tortoise’s limited energy stores, leading to starvation and dehydration. For this reason, the use of a refrigerator with a temperature regulator is often favored by experienced keepers, as it provides far greater stability than a garage or outdoor burrow.
The tortoise should be placed in a ventilated container filled with an insulating, moisture-retaining substrate like dry coconut coir, shredded newspaper, or soil. The brumation period typically lasts between eight and twelve weeks, requiring passive monitoring. Weekly weight checks are mandatory; a tortoise that loses more than 1% of its body weight per week, urinates, or defecates, must be woken up immediately.
Safe Recovery After Brumation
Ending brumation must be managed carefully to avoid shocking the tortoise’s system. When brumation is complete, the tortoise should be removed from the cold environment and allowed to warm up gradually at room temperature over several hours. Sudden exposure to high heat is dangerous, so the transition must be slow and controlled.
Once the tortoise is visibly alert, the immediate priority is rehydration. It should be placed in a shallow bath of lukewarm water, deep enough to reach its chin, for at least 30 minutes. This soaking encourages the tortoise to drink, replenishing fluids lost during the dormancy period.
The tortoise should be moved to its fully heated enclosure immediately after the initial soak, where heat and UV lighting are fully restored. Owners should compare the post-brumation weight to the starting weight, ensuring total loss is within a safe limit (typically less than 10%). Within a few days, a healthy tortoise should begin eating small amounts and eliminate waste, signaling a successful return to its active season.