Hibernation is an important part of the natural cycle of desert tortoises, box turtles, and many other turtles and tortoises kept as pets in Arizona. Make sure you know if your turtle or tortoise is supposed to hibernate or not.
Hibernation, sometimes referred to as burmation, is an adaptation used by many species around the world, including many tortoise species, to survive cold weather. Like all cold-blooded animals, tortoises are unable to produce their own body heat. As the temperatures outside fall their metabolism slows. A slower metabolism means every physiologic activity, from digestion or reproduction, slows too.
Hibernation is natural and recommended for healthy tortoises. However, it’s extremely important to point out that not all tortoise species can or do hibernate. Before you prepare your pet for hibernation make sure to establish that it will hibernate. For species that do, hibernation is part of their yearly life cycle and many tortoises can even become ill if prevented from doing so year after year.
While hibernation is natural and healthy, sick tortoises should never be hibernated. For a sick individual, hibernation can be seriously dangerous and potentially deadly. To survive hibernation a tortoise needs good fat and water reserves. Sick tortoises often aren’t eating well and thus not storing the energy they’ll need for successful hibernation. In addition, a tortoise’s immune system slows during hibernation. A sick tortoise won’t be able to adequately fight off any infection.
Preparing for Hibernation:
Before hibernation every tortoise should be examined by a qualified veterinarian to assure they are healthy. Your veterinarian will check for signs of infection (i.e. runny nose or eyes, coughing, respiratory difficulty, etc.) and assess their body condition. Often veterinarians will recommend tests such as checking a fecal sample for parasites, blood work to check for hidden infections and assess overall organ function, and x-rays to check for bladder stones or retained eggs.
We strongly recommend an annual pre-hibernation exam between late August and mid September to ensure that your turtle or tortoise is healthy and ready for hibernation. To schedule a prehibernation exam online click here or call 480-275-7017.
Once your pet has passed their physical exam, it’s time to prepare them for hibernation. Monitor your tortoise closely as Fall approaches. Usually starting in late September or early October, as the nights start to cool into the 60s, you will notice your outdoor tortoise becoming less active. At this time stop feeding your tortoise any supplemental produce (i.e. Kale, Lettuces, Collard Greens, etc.). A small amount of grass ingested prior to hibernation usually isn’t harmful, but a stomach full food can be. Undigested foods left in the digestive track will not be digested during hibernation and will rot. During this time it is important to soak your tortoise daily in a shallow bowl. This will help them to build up water reserves and stimulate them to empty their bladder and bowels.
As the temperatures continue to drop it will stimulate your tortoise to seek a hibernaculum, an appropriate shelter in which to hibernate. You can provide one by creating a constructing an artificial burrow to insulate the tortoise from the cold and protect them from getting wet. Adding hay or straw into the burrow can further increase the insulation. Click here for a diagram on building an artificial burrow for your tortoise.
Most tortoises will hibernate once ground temperatures remain below 60 degrees. An easy way to monitor ground temperatures is by using a simple kitchen thermometer stuck into the soil of your tortoise’s burrow. It is important to make sure ground temperatures do not exceed 60 degrees for an extended period of time, as these warmer temperatures will cause your tortoise to burn through its fat reserves too quickly. Ground temperatures below 39 degrees are also dangerous and can result in tissue and eye damage and death. If ground temperatures exceed 60 degrees for an extended period or drop below 39 degrees you should bring your tortoise indoors forgoing hibernation, relocate them to a more appropriate area of the yard, move them into an insulated box in a cool area of the house or garage (see below), or hibernate them artificially in a refrigerator (see below).
It is very important to check your tortoise occasionally, at least once a month, to make sure hibernation is going well. Keep a chart of your tortoise’s weight using a digital gram scale, your tortoise should not lose more than 1% of its body weight per month. For example, if your tortoise weighs 500 grams then 1% of its body weight would be 5 grams. Tortoises should be brought out of hibernation immediately and be examined by a veterinarian if they are losing too much weight, show any signs of illness, are found attempting to bask on cold days, or remain active within their burrow.
While checking your tortoise it is also important to make sure they have not urinated. A tortoise’s urinary bladder actually serves as their water storage during hibernation. If you notice your tortoise has urinated they will need to be rehydrated. If not they will easily become dehydrated and die. Warm your tortoise to room temperature slowly and then allow them to soak themselves in shallow water to drink. Before cooling them down again and returning them to their burrow, be aware that urination can be a sign they are remaining active within their burrow. Take a moment to check over their hibernation conditions and remain observant for any other signs of problems.
If you do need to bring your tortoise out of hibernation, warm them slowly to room temperature, do not warm them quickly. Tortoises that can no longer hibernate for medical reasons will then need to be maintained indoors, fed, and housed in an appropriate warm enclosure for the remainder of the winter.
Hibernating tortoises indoors can be tricky, whenever possible hibernating them outdoors naturally is recommended. Tortoises will not go into hibernation unless the temperatures in the environment cue them to do so. When hibernation outside is not an option, place your tortoise inside in an insulated box and keep him in a part of the house or garage that stays between 50 and 65°F. If it is much warmer, your tortoise may not be able to hibernate properly and become ill. If it drops much below 40°F, your tortoise runs the risk of damage from the cold temperatures. Alternatively, indoor tortoises you can simulate the drop in outdoor temperatures to initiate hibernation utilizing a refrigerator. Slowly lower the temperature until you reach hibernation temperatures. For more information on indoor/artificial hibernation visit http://www.tortoisetrust.org/articles/Refrigerator.htm.
Check on your tortoise periodically. Soak it in a room temperature shallow water bath for 15 minutes every 4-6 weeks to prevent dehydration. Most tortoise will hibernate for 4-6 months. If the temperature is much above 65°F, the desert tortoise may be active and use up its energy stores too quickly. If the temperature is much colder, the desert tortoise may develop health problems. Once the overnight temperatures are getting above 65°F and there are warm (85°F) sunny days, your tortoise can be removed from hibernation and placed back into the outside enclosure.
Safer Hibernation and Your Tortoise. A C Highfield & Annie Lancaster. http://www.tortoisetrust.org/articles/safer.html
HIBERNATION GUIDELINES by Paula Morris http://www.chelonia.org/articles/hibernationpaula.htm
Hints on Hibernation by Michael J. Connor, PhD http://www.tortoise.org/general/hibernat.html
Captive Desert Tortoise Cold Weather Care from the Arizona Game and Fish Department http://www.azgfd.gov/w_c/tortoise/coldweathercare.shtml