As fall and winter arrive and the days grow shorter, your captive tortoise or box turtle will begin to slow down. Before long, he may go into hibernation, the dormant state when certain animals "sleep," with a corresponding drop in body temperature and metabolism. This is their way to pass winter, when foraging is limited and it is more beneficial to save energy.
There are no absolute rules as to the proper length of hibernation for captive tortoises and box turtles. Generally speaking, indoor hibernation will occur between mid-October and late March. Small or young animals might hibernate for as long as 8 to 10 weeks, but 6 weeks may be adequate. Larger animals (mostly Testudo species) might spend as long as 12 to 14 weeks in hibernation. Box turtles from the southern or south eastern United States may require as little as 4 to 6 weeks in hibernation.
Some period of hibernation is almost certainly beneficial to your pet, and while animals should be woken at the first sign of concern, if a tortoise is doing well and losing no more than the expected amount of weight, there is no reason to end hibernation early. Make careful notes of weight loss. By the end of hibernation, a mature tortoise should not lose more than 6 to 7 percent of his pre-hibernation weight. Tortoises should be weighed and examined regularly during hibernation.
You should wake your pet up if he starts to show signs of activity, has spent a reasonable amount of time hibernating or shows signs of a health problem. You should also wake him up if his weight loss is approaching your comfort limit (he may not have stored enough fat for his extended snooze.)
After you remove your tortoise from his hibernaculum (den in which he has hibernated), keep him at room temperature for a few hours. This will mimic the time it would take him in the wild to emerge from his burrow, into bright, warm sunlight. Then move him to his normal enclosure, and maintain him within his POTZ (Preferred Optimal Temperature Zone-see related care articles for further information). Soak him daily for a week, and he should resume normal behavior and eating within 3 to 4 days.
Use lukewarm water, which is only deep enough to reach his chin, or the bridge (where the plastron, or bottom shell meets the carapace, or top shell). The reptile should be soaked for 20 to 30 minutes daily. Soaking will encourage your pet to eliminate the wastes that have been accumulating in his body during hibernation. The accumulation of wastes within the colon and bladder can lead to the release of toxins into the animal's body, as well as to the inability to pass hard dry stool, and to the development of bladder stones and gout. Since many tortoises and turtles come from areas of the world where water is scarce, they will often not urinate until they know that a source of water is available. This is a method of water conservation. Misting (with a spray bottle) at least once a day will increase humidity levels in the enclosure and, by mimicking rainfall, will encourage tortoises to eat, drink and evacuate waste.
Many tortoises that do not eat within 3 to 4 days, are simply not warm enough, or are not exposed to sufficiently bright radiant light. A focal bright, "hot spot" is recommended. These conditions are necessary to stimulate the reptile to eat. In the wild your pet would emerge from a cool, dark burrow into bright sunlight, and quickly warm himself by basking in intense sunlight. A warm (generally not warmer than 20 degrees Celsius or 68 degrees Fahrenheit), bright room simply does not mimic the animal's natural environment.
If your tortoise does not show any definite signs of illness and is behaving normally except that he is not eating, the first step is to review your husbandry techniques. In particular, pay attention to lighting temperature, the presence of a focal "hot" spot (for basking) and photoperiod (recommended number of light and dark hours).
Failure to eat is probably the most common post-hibernation concern. If you cannot detect a problem in the tortoise's environment, if the animal shows any other signs of a health problem, or if he does not begin to eat within four to five days of correcting any husbandry problems, a visit to your reptile veterinarian is warranted. Conditions commonly associated with hibernation include frost damage to eyes and limbs, injury from predators (rodents, raccoons), sores or corneal ulcers from rough bedding, pneumonia and excessive weight loss. The reptilian immune system does not function optimally at the temperatures required for hibernation. Reptiles hide illness very effectively, and many are subclinically (not obviously) ill when they begin hibernation. Disease may therefore have worsened during hibernation.