The debate on whether to hibernate or over
winter a temperate zone tortoise (Mediterranean species) or box
turtle weighs heavy on the minds of those who own these animals.
There is allot of differing opinions on this subject. Many of
the books on the market suggest that it is not necessary to
hibernate a captive turtle. According to this train of thought a
turtle who is kept at summer temperatures and eats well will
show no ill effects from a lack of hibernation. These books do
suggest that fertility and the desire to reproduce are the only
ill effects of omitting hibernation.
The other theory suggests that it is indeed advantageous to the long term health of the turtle to duplicate what they would experience in nature. These species have an annual cycle of building up reserves in the warm months in anticipation of a winter "brumation". the prevention of long term kidney damage, anorexia, and loss of fertility being sited as some of the reasons why a short brumation of these temperate zone species is essential.
Armed with allot of information I nervously made the decision to hibernate Ellie this winter; she is one of my Russian Tortoises (Testudo Horsefieldi). The FIRST CONSIDERATION that needs to be made is whether the animal is healthy and has not had any serious illness in the past year. They must also have adequate fat reserves. She qualified for both. A.C. Highfield (the expert in this field in my opinion) has a pre-hibernation checklist which I followed for both of those qualifiers. An author named Brian Pursall also has a book detailing hibernation.
Ellie was giving me the cue this fall for the SECOND CONSIDERATION. They must have an empty digestive tract before they enter hibernation. This is critical and is one of the most common errors made in the hibernation process. Undigested food in the animal will rot during hibernation usually resulting in the death of the animal. The information available suggests a two to four week fasting period, which is needed to completely empty the digestive system before entering hibernation. Larger tortoises will require 4 weeks. Small tortoises may require slightly less time. Towards the beginning of October Ellie was only eating every second to third day. I started a journal on her eating habits at this time. She ate less and less over the next few weeks. On October 20th she ate her last meal. I kept her in a warm environment (inside the house by now). She preferred to hide under a rock rather than bask in the artificial sunlight. I bathed her every other day to encourage voiding all remaining matter in her digestive tract and to encourage hydration. I determined that she had an empty digestive tract three weeks after starting her fast.
I then moved her to the basement where the temperature was in the mid-sixties and she was in the dark so she would enter a deep sleep. After five more days I put her in her hibernacula hoping I would be seeing her alive and well rested after a short hibernation.
CONSIDERATION THREE is temperature range
desired during the hibernation. The optimum range is 39 - 41
degrees with a safe range of 35 - 50 degrees for Mediterranean
Tortoises. I bought a digital thermometer that has minimum and
maximum readings for temperature and humidity.
During the fasting period I put this thermometer in our refrigerator to make sure that the temperature fluctuations fit into the range required. It did, in fact 41 - 43 degrees was the typical temperature.The lowest ever recorded was 38 . The highest was 45 . I kept track of the temperatures every day she was in hibernation. It is said that at the 39 - 41 range the tortoise will lose very little weight. At temperatures higher or lower the tortoise will dig either upward to reach colder temperatures or downward to reach warmer temperatures as the soil gradient occurs in nature. This causes an energy expenditure which should be minimized as much as possible. I therefore chose the crisper drawer of our refrigerator and filled it with shredded newspaper as the hibernacula; this area of the refrigerator maintained the most constant temperature. The humidity was around 30%. I would spritz the shredded newspaper once a week raising the humidity for a day into the 60% range. I must point out that box turtles need a much higher and more constant humidity level. None of my sources suggested a humidity range required. This is the one area I was unsure of throughout the hibernation.
CONSIDERATION FOUR is the time spent in
hibernation. Many articles describe a five month hibernation. In
nature, it can be five months long or it may only be a couple of
months depending on the climate/region. Once again, I felt that
A.C. Highfield's opinion made the most sense. He recommended
hibernating a temperate zone tortoise, but for a short period.
He suggests 8 to 10 weeks as a safe amount of time to hibernate
them. I ended up getting her out 7 weeks into hibernation
because I was unsure of the humidity requirements and I didn't
want her to dehydrate.
I checked on Ellie once a week during the hibernation period; which included, taking her gram weight on a digital scale. She should have lost no more than 6 1/2 grams total throughout hibernation this year; during the actual 7 week sleep, she lost 4 grams. A tortoise or turtle should only lose 1% of body weight per month of hibernation. I had calculated that to be .95 gram per week for Ellie. If they are losing weight more rapidly than that; then, something is wrong. Typical problems include incorrect temperatures (causing them to reflexively dig), dehydration, and/or illness.
Well, it is now three weeks since I woke her up. You are supposed to get them out and warm them up rather quickly. I brought her out of the refrigerator and put her in a box in a warm room. Within 15 minutes, she was starting to stir. After she had spent 30 minutes in the box, I held her for 10 minutes to warm her and do a visual check of her ears, eyes, nose, shell, etc. All looked good. I then put her into the open top terrarium (6 ft wading pool) she calls home when it is too cold to be outside. She sunned herself for about an hour. You are supposed to encourage them to drink and void stored uric acid soon after they wake.
I put her into a warm shallow bath for 10 minutes after she was fully awake. Shortly after removing her from the bath she expelled a huge amount of liquid. By the next day she was acting and eating like it was spring. As of this writing, Ellie has added 28 grams to her post-hibernation weight.
The hibernation journey was very nerve racking to me. Ellie is an important member of our household. I would not have been able to hibernate Ellie if I wasn't confident that all of the right conditions and checkpoints were in place to do so. It is important not to rely on just one article or book for information.I sorted through all the information available and worked with the information that made the most sense. I am convinced that Ellie was hibernated correctly. She is very alert and appears ready to take on the world. I will attempt to hibernate Gus and Amy next year and lengthen the hibernation period from 7 to 12 weeks. Gus and Amy weren't hibernated this year because they were just acquired in July. The general rule of thumb is not to hibernate a turtle or tortoise the first year that you acquire them because you don't know their health history for one full year.
Now, our hibernation journey is complete. I hope to experience another journey with Ellie this year. I hope to experience egg laying, incubation, and hatchlings. Did I mention that Gus, my male Russian thinks Ellie looks mighty fine since she rejoined him.
This article was written in 1997. As of this post writing I have seven Russian Tortoises. This is my fifth year of hibernating tortoises. I have never had a problem with my tortoises during their hibernations. I reside in Nebraska where it is too cold in the winter for me to feel comfortable letting them hibernate outdoors. The refrigerator method has worked well for me.
(c)1997 Shelly Jones
In the crisper
The max/min thermometer
They warm up after a long sleep