The Hibernation Journey

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The Hibernation Journey - Shelly Jones

The debate on whether to hibernate or overwinter a temperate zone tortoise (Mediterranean species) or box turtle (Terrapene species) weighs heavily on the minds of those who own these animals. There are a lot of differing opinions on this subject. Many of the books on the market suggest that it is not necessary to hibernate a captive tortoise or 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.” Prevention of long term kidney damage, anorexia, and loss of fertility were cited as some of the reasons why a short brumation of these temperate zone species is essential.

Armed with a lot of information I nervously made the decision to hibernate Ellie this winter; she is one of my Russian tortoises (Testudo horsfieldii). 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. The animal must also have adequate fat reserves. Ellie qualified for both.

Ellie was giving me the cue this fall for the second consideration: the animal must have an empty digestive tract before entering 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, 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 the animal is able to safely enter hibernation.

Unwilling to take chances, I chose to wait the full four weeks. I began to prepare her when she was brought inside for the season. She was already winding down naturally from being outdoors during cooler weather and weaker fall sunlight. The first two weeks indoors I provided a 60-Watt spotlight. I reduced the bulb to a 40-Watt the third week. The last week of her fasting, I used a 25-Watt bulb for her spotlight. She basked less and less and slept much more during these four weeks. She had no desire to eat. During the fast, I bathed her every other day to encourage her to void all remaining matter in her digestive tract and to encourage hydration. I determined that she had an empty digestive tract four weeks after starting her fast. I then placed her in her hibernaculum.

Consideration number three is finding the proper hibernaculum to provide the temperature range desired during the hibernation. The optimum range is 39°-41° F with a safe range of 35°-50°F 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 required range. It did. In fact 41°-43° F was the typical temperature. The lowest ever recorded was 38° and the highest 45°F. I kept track of the temperatures every day she was in hibernation. It is said that at the 39°-41°F range the tortoise will lose very little weight. At temperatures higher or lower the tortoise will either dig upwards to reach colder temperatures or downward to reach warmer temperatures as the soil gradient occurs in nature. This digging causes an expenditure of precious energy and should be minimized.

I therefore chose the crisper drawer of our refrigerator as a hibernaculum and filled it with shredded newspaper. 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 into the 60% range for a single day. I must point out that Box turtles need a much higher and more constant humidity level. None of my sources suggested a humidity range. This is the one area I was unsure of throughout the hibernation.

Consideration number four is the time the turtle or tortoise spends in hibernation. In nature it can be five or six months long, or it may only be a couple of months, depending upon the climate and region. I felt that moderation made the most sense. I ended up getting Ellie out seven weeks into her 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. This included taking her gram weight on a digital scale. She should have lost no more than 6.5 grams total throughout hibernation this year, and during the actual 7-week sleep she lost 4 grams. A turtle or tortoise should lose only 1% of its body weight per month of hibernation. I had calculated that to be 0.95 gram per week for Ellie. If the animal is losing weight more rapidly than that, then something is wrong. Typical problems include incorrect temperatures (which causes them to reflexively dig and waste fat reserves), dehydration, and/or illness.

Well, it is now three weeks since I woke Ellie up. You are supposed to get them out of their sleep 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’d spent thirty minutes in the box, I held her for ten 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 (a 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 soon after they wake in order to void stored uric waste. 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, Ellis has added 28 grams to her post-hibernation weight.

The hibernation journey was very nerve-wracking for 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 twelve 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 and should wait at least one year to detect health problems that could affect their hibernation.

This article was written in 1997. As of this post-writing I have seven Russian tortoises. I have successfully hibernated my tortoises for three seasons. I now hibernate them for 16 weeks. I have never had any problems with any of my animals during their winter nap. I reside in Nebraska where it is too cold in the winter for me to feel comfortable letting them hibernate outdoors. A refrigerator, though, makes an ideal hibernaculum because you can control the temperature and check on your tortoises. If your climate does not offer ideal outdoor conditions, please try the fridge!

It should be noted that turtle and tortoise care research is ongoing. As new information becomes available we share this on the World Chelonian Trust web site at www.chelonia.org. Serious keepers find it to be a benefit to have the support of others who keep these species. Care is discussed in our free online email community, which may be joined from the web address above. Please contact us about the many benefits of becoming a member of the World Chelonian Trust.

Shelly Jones <shellytortuga@yahoo.com>

World Chelonian Trust

www.chelonia.org

PO Box 1445

Vacaville, CA

95696

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