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
Getting weighed |
In the crisper |
The max/min thermometer |
They warm up after a long sleep |