There is a right way and many wrong ways to hibernate-or rather, brumate-a pet reptile, if it is even necessary at all.
A significant part of my time working with clients and their scaly pets is devoted to troubleshooting health problems. I always ask for a description of the basic husbandry that has been given to the pet in question. If the pet is a tortoise, the customer will inevitably say, “Every winter, we put him in a box and place it in a corner of the garage. At the first sign of spring, we wake him up.” And just as inevitably, I ask, “Why do you do that?” I usually get a look of bafflement, as they reply, “Aren’t they supposed to hibernate?”
Hibernation in the wild is a complex and delicate process, and while it can be efficiently replicated in captivity, it generally serves no purpose to do so unless the end goal is to breed the animal. Keep in mind, animals in the wild sometimes die in hibernation—that is an even more likely outcome if they had not been in tip-top condition at the start of the process. However, just because the natural world is a harsh and difficult place does not mean that we should try to replicate those elements in captivity.
In fact, reptiles don’t actually hibernate at all. They brumate. Hibernation involves lowering the body’s temperature such that the heart and breathing rates slow down, allowing the animal to enter a state in which it uses up very little energy or body fat through the season. Brumation is more of a basic lethargy, in which the reptile is still capable of limited action.
Another important factor in deciding how to brumate a pet—or whether or not to do it at all—is the pet owner’s local weather pattern. True hibernation is an evolutionary response to freezing or near-freezing climates. For instance, here in the San Francisco Bay Area, our winters rarely hit freezing temperatures for more than a few hours out of the year, and much of our winter can be balmy and warm. Consequently, a box-in-the-garage technique will have a tortoise in the precarious state of bouncing back and forth between a pre-brumation lethargy and post-brumation activity. This means that stores of body fat will be used up, whereas in true hibernation and even brumation, they would be barely touched. The poor tortoise might literally starve, or at best get pneumonia, as a result of the supposed “hibernation.” So, how pet owners approach this subject varies wildly depending on whether they live in, say, New Orleans or Nome, Alaska.
The best bet for most reptiles that function purely as pets is to keep them in what I call an “eternal spring.” By keeping the cage temperatures constant—or modified by subtle ambient temperature fluctuations in the house—a pet owner can keep their animals feeding and active throughout the winter. Some snakes will shut their feeding response anyway in an acknowledgement of changes in the length of the days—in my experience, rosy boas seem particularly susceptible to this—but otherwise, they remain vigorous and happy through the winter.
Cooling is necessary should you want to breed most reptiles, as the process spurs the animals through hormonal cycles that induce egg and sperm production and the accompanying mating behaviors. The strategies employed to achieve this vary a lot with geographic location and the variability of temperatures within the owner’s home. Remember, however, that brumating animals are, in fact, strategizing to escape the very worst extremes of the cold and choose locations that are cold, yet buffered, without ever actually freezing.
I have a long hallway in the back of my shop that gets cool in the winter months, staying in the low 50s to low 60s consistently throughout the seasons, despite wild fluctuations outside. It is perfect for cooling most of our colubrid snakes. I recommend doing the same for breeder snakes. Colubrid snakes do best if brumated at about 55 degrees Fahrenheit, for about 10 to 12 weeks. We set them up in individual shoe or sweater boxes, on clean bedding and with a water bowl. We check on them at least once a week to make sure they are doing well and that their water is clean and fresh.
Snakes should also be prepped for brumation a few weeks prior. This preparation includes a final feeding, followed by a week at normal temperatures to allow for digestion, followed by a few weeks at ambient room temperature but with the cage heat turned off. The goal is for the snakes to go into brumation with nothing in their digestion track that might cause problems when they no longer have heat, and that they enter their winter slumber in a safe and gradual manner.
The strategy with breeding pythons and boas is different. For some, the slight change in ambient household temperatures between summer and winter might be enough to do the trick. Another idea is to keep breeder snakes in long cages capable of a wide variation in temperatures; large snakes will often gravitate to the cool end of the cage and stay there through the winter, semi-brumating themselves in an elective manner.
Most lizards will cycle hormonally in a similar manner, triggered by only slightly lowered cage temperatures. These animals respond not only to temperature fluctuations, they are often also cognizant of the lengthening and shortening of the days. Reptiles are often more perceptive than we realize.
Getting back to the tortoise keepers—once again, if you don’t intend to breed them, there is no reason to induce brumation. I believe most tortoise owners are relying on popular mythology when they do this to their beloved tortoises. It’s the same mythology that makes some folks think they only need to feed their snake once a month, and that reptiles will grow only to the size of their enclosure. All of these ideas are wrong.
If you do want to breed tortoises, keep in mind that many species from tropical regions never experience anything like what we think of as winter, and for all intents and purposes, the same natural temperature drop in households should be enough for them as well. The sole exception in my mind is the Mediterranean complex of tortoises: Greeks, marginated, Hermann’s and, most popularly, Russians. These animals brumate at right around 40 degrees Fahrenheit, and the easiest and most consistent way to accomplish this is to refrigerate them. I would dedicate a specific refrigerator to this purpose, with the essential caveat that the refrigerator must be opened with regularity to prevent suffocation.
In summary: Brumate only for the purpose of breeding your animals. Make sure they are in good health and with good body weight beforehand. Strategize to find the best method and situation to maintain consistent temperatures. Approach brumation gradually, and make sure all animals have nothing in their stomach or intestines before brumating. Research the specific animals in question to determine optimum brumation temperatures, length of time in brumation and start time.
And finally, have a nice nap.
Owen Maercks has enjoyed being immersed in the world of professional herpetoculture for nearly 30 years. His store, the East Bay Vivarium in Berkeley, Calif., is one of the oldest and largest herptile specialty stores in the U.S.