If you keep a tortoise from a temperate climate zone, such as a Russian (Testudo horsfieldii), Hermann’s (T. hermanni), or desert tortoise (Gopherus agassizii), you’ll need to provide your pet with a chance to brumate (the reptile version of hibernating).
But brumation is not something to initiate haphazardly – it can be very dangerous if not carried out in the proper manner. Among other things, this means properly preparing your tortoise for the event, monitoring your pet regularly to ensure he’s remaining healthy, and perhaps most importantly, providing the appropriate environmental conditions.
Over time, keepers have devised a number of different ways to do exactly that. One of the most popular methods developed is known as the “fridge method.” I’ll explain everything you need to know about the fridge method, including a plan of attack, below.
What Is the Fridge Method?
It is critical that you keep your tortoise at the proper temperature range during his brumation. If the temperatures fall too low, the intracellular water in his body may freeze, which will often cause him to become blind or die. Conversely, if the temperatures rise high enough, his metabolism will begin speeding up. Because he’s not being fed during this period, he could lose a great deal of weight or even starve.
The exact temperature range you should target for brumation will vary from one tortoise to the next, based on a variety of factors, including the species, sex, and age of your pet. However, 37- to 45-degrees Fahrenheit is typically regarded as the best temperature range for most individuals.
Unfortunately, it can be challenging to provide temperatures within this range.
Most people maintain their homes far warmer than this during the winter, and the outdoor temperatures may be significantly higher or lower than this, depending on your geographic location. The outdoor temperatures are also likely to fluctuate drastically.
To address this problem, keepers developed the fridge method. This essentially involves purchasing and setting up a second refrigerator (you do not want to use the same one you keep your family’s groceries in). The refrigerator is kept within the 37- to 45-degree range. You’ll then place your pet in an insulated box, which is then placed inside the refrigerator for the duration of the brumation period.
There are other hibernation strategies you can use, such as the “box method” and “burrow method.” However, the fridge method has become a popular approach, second only to the box hibernation method.
Fridge Method Explained
There are two key reasons the fridge method has become so popular.
For starters, it is likely the safest method for hibernating your tortoise, as it provides the most consistent temperatures. And secondly, it is also quite easy to implement. However, the process will involve two distinct components – you have to set up the refrigerator and hibernation box, and you must also prepare your tortoise properly.
Preparing the Refrigerator and Hibernation Box
Because it can take some time to set up a refrigerator and hibernation box, you’ll want to start this part of the hibernation process at least one week beforehand (and ideally, several weeks prior).
- Purchase and install the refrigerator. Be sure to select a refrigerator of the appropriate size. If you are only keeping one tortoise, a small “dormitory” refrigerator would likely be large enough, but if you maintain a colony of half a dozen tortoises, you may need a full-size unit. Try to set the refrigerator up in an out-of-the-way location but be sure that the room itself remains warmer than 37 degrees, as refrigerators have no mechanism for increasing the temperature; they can only cool the internal temperature.
- Select your tortoise’s hibernation box. You obviously can’t simply place your tortoise in a refrigerator, so you’ll need to purchase or construct a suitable box to contain him. A number of options will work, but most keepers likely utilize plastic storage boxes with a few ventilation holes drilled into the sides. However, an insulated box will provide even greater protection against drastic temperature swings and is therefore worthy of consideration. Also, drill at least one hole in the hibernation box for a thermometer probe. In all cases, the box should be large enough to permit the tortoise to turn around completely.
- Set up the hibernation box. Fill the box about ½ to 2/3 full of a suitable substrate. Shredded newspaper is a popular choice, but soil or a soil-sand mixture may also work. Insert the thermometer probe in the hole you drilled. If possible, route the cord so that the thermometer’s display can be placed outside the refrigerator. This way, you can monitor the temperatures without having to open the door.
- Monitor and adjust the temperatures as necessary. Over the next week, you’ll want to monitor the internal temperatures of the hibernation box and make adjustments as necessary. This is part of the reason it is important to set up the refrigerator before initiating the brumation period.
Preparing Your Tortoise for Hibernation
The primary thing you need to do before allowing your tortoise to brumate is to empty his digestive tract completely. This is important because any food left in his digestive tract is likely to rot, given that his digestive processes won’t be proceeding as they would when he’s active. This could cause him to vomit or become seriously ill.
Accordingly, you’ll want to start withholding food for 2 to 4 weeks before you intend to initiate brumation (and potentially even longer for very large tortoises). Most keepers also begin withholding water approximately one week before the start of brumation.
Safe Tortoise Brumation: Important Tips
The refrigerator method helps to eliminate a lot of the difficulties some other hibernation strategies present. Most importantly, it makes it easier to keep the temperature levels consistent throughout the entire process.
However, there are some additional things you’ll want to do and be aware of when carrying out the fridge method:
- Monitor the temperatures on a daily basis. Even though the fridge method helps keep the temperatures relatively constant, you’ll want to glance at the thermometer display at least once per day. If you notice the temperature climbing or falling outside the ideal range, take the steps necessary to fix the problem.
- Inspect your tortoise once per week. You don’t want to disturb your pet unnecessarily, but it is a good idea to open the hibernation box once per week to assess his condition. He should be asleep, yet conscious enough that he’ll pull his legs away if they’re lightly pinched. Also, ensure that he doesn’t exhibit any sort of nasal discharge.
- Maintain the brumation period for an appropriate length of time. The best brumation length will vary based on a variety of things, including your tortoise’s species, age, and size. Generally speaking, tortoises from areas with longer winters should be brumated for longer. Older and larger tortoises can also withstand longer brumation periods than younger or smaller tortoises. With all that said, a typical brumation period should last between 4 and 12 weeks, though some species (such as Russian tortoises) may brumate for as long as 16 weeks.
- End brumation any time your tortoise becomes active. If at any point in time you notice that your tortoise has become active, it is imperative that you break the brumation period and return him to his normal enclosure. Never attempt to re-initiate brumation in a tortoise who’s become active.
- Reinstate normal conditions gradually. It is generally preferable to break your tortoise’s brumation in a gradual manner. So, you may start by simply removing the hibernation box from the refrigerator for a day or two. Then, you can return your pet to his normal enclosure. However, you don’t want to turn on his lights and heating devices for 12 to 14 hours per day yet – start by only turning them on for about 6 to 8 hours. After approximately one week of this, you can restore full “summer” conditions.
- Begin offering water immediately; begin offering food after several days. While your tortoise may begin drinking water almost immediately after exiting brumation, he probably won’t begin eating again for a few days.
Citations
- HermannsTortoise.co.uk – Hibernation
- Arizona Exotic Animal Hospital – Hibernation Recommendations for Turtles and Tortoises
- SwellReptiles – Tortoise Hibernation Guide
