Hibernation

SUCCESSFUL HIBERNATION OF MEDITERRANEAN TORTOISES

For most new or inexperienced tortoise keepers the dreaded "H" word often instils a complete blind panic, brought on by an irrational fear of accidentally killing their beloved pets. In fact, if this had still been the 1970's I would agree that most tortoises definitely didn't wake up! However, times have moved on and we now have the knowledge to safely guide our charges through a much needed brumation period.  Furthermore, failure to hibernate tortoises which are biologically programmed to do so, will eventually adversely affect the tortoise's health..... The plusses of hibernating far out way the minuses of not doing so as you will see as you read on...

COMMON MISTAKES

The common mistakes made by most keepers thirty years ago (and unfortunately still a small percentage today) were to either:

(A) Feed the tortoise just prior to hibernation,

(B) Hibernate at temperatures above 10*c

(C) Hibernate at temperatures that dropped below 0*c

(D) Not to offer protection against predators

(E) Hibernate a tortoise that was suffering from an illness

(F) Any combination of the above.

To fully recognise the reasons why the above-mentioned circumstances or procedures were indeed DISASTROUS MISTAKES we need to look at each case and understand the biology of what is actually happening to influence the obvious costly outcome:

Firstly, let's start with;

(A)  FEEDING PRIOR TO HIBERNATION

A tortoise's metabolism when in a state of brumation almost completely shuts down, it's heartbeat slows down to virtually nil, it's senses shut off and it's bodily functions also cease - including digestion - this is the key factor here. Any food which is therefore left inside the animal's gastric tract will not be digested and so simply rots. This in turn causes severe internal problems from the gasses produced from the rotting food.

(B)  HIBERNATING AT WARM TEMPERATURES

 A tortoise has an inbuilt mechanism which tells it to wake up when the surrounding temperature reaches 10*c.  In their natural environments they will have buried into the ground where the temperature remains a fairly constant 3 to 7*c over the winter period, only reaching 10*c with the onset of spring.

At 10*c a chemical reaction happens inside the tortoise and glycogen is released from its stores and flushed into the blood stream. This gives the tortoise an initial energy boost sufficient for it to start moving, basking and eating again.

However, a tortoise has only so much of this energy boosting product available, so consequently when in artificial hibernating situations where the temperature is often allowed to fluctuate to 10*c or above the tortoise will have used up its supply and will be lifeless upon awakening. Only immediate hydration therapy with a glucose solution will then stop the tortoise from perishing.

(C)  HIBERNATING AT FREEZING TEMPERATURES

 A fairly obvious one this!
Tortoises subjected to temperatures of 0*c or below will literally freeze to death. Even in the best case scenario of a tortoise surviving it realistically could end up being blind due to the fluid in the eyes freezing and causing irreparable ocular damage.

(D)  NO PROTECTION FROM PREDATION

Another hopefully obvious one, but still this was responsible for many chelonia deaths in the 70’s and 80’s.
 Tortoises kept in flimsy cardboard boxes and placed in sheds and outbuildings were often subjected to rodent attacks, or when left to hibernate naturally outside were literally eaten alive by rodents, opportunistic hedgehogs, ants, birds, foxes and so on.

(E)  HIBERNATING WHEN NOT 100% FIT AND HEALTHY

Like the rest of a tortoise's metabolism, the immune system also dips when brumating. So, any slight ailment that the tortoise may have will only be exacerbated when it hasn't got the normal aggressive immune system that a warm, active, tortoise has. One point to note here however is that any bacterial disease will slow down it's multiplication ability when placed at temperatures of around 3 to 7*c (ideal hibernating temps) but will have a usual rate of invasion at temps higher than this. Hence disease problems are considerably exacerbated when a tortoise is also hibernated at incorrect temperatures.

NOW WE KNOW THE COMMON MISTAKES; LET’S AVOID THEM FOR 100% SUCCESS

With the typical hibernating mistakes already identified and touched upon, it is now a very simple task to ensure that we simply do the complete opposite to ensure a very safe and effective method of chelonian brumation.......

THE WINDING DOWN PERIOD

As already mentioned, any food left in the stomach of a tortoise when put into hibernation will simply rot, so with this in mind the correct measure to take is to ensure that your tortoise's stomach is completely empty;

You need to completely starve the tortoise of ALL food prior to the hibernation period.

If a tortoise is kept outdoors and has ready access to a natural food supply, don't worry as you'll find that the tortoise will naturally start eating less as the colder days draw in until it such time the ambient temperature is sufficiently cold whereby it stops eating altogether. This is normal and natural.
If a tortoise is being housed artificially indoors, over a period of a few weeks gradually start to decrease its heat and light levels (mimicking the change from late summer to autumn.)  And at the same time simply start to cut down it's food intake over the same period.
Then after a few weeks switch off all heat, and start the 100% starvation period.

TOTAL STARVATION PERIOD

The 100% total starvation period I would recommend varies on the age and size of the tortoise concerned.
Tortoises up to 1 year old – 7 to 10 days total starvation.
Tortoises 1 to 2 years old –  14 days total starvation
Tortoises 3 to 5 years old -   21 days total starvation
Tortoises 6 years plus -         28 days total starvation

Although a tortoise should have no food inside it's stomach throughout hibernation, it should have a full bladder, so regular bathing should continue throughout the winding down and starvation period to ensure adequate hydration levels.

A BOX WITHIN A BOX

After your tortoise has been sufficiently starved its time to box him up in his “bedroom” ready for his long slumber.
The best method is to employ two boxes; an inner and an outer.
The inner box should be of fairly snug dimensions, be constructed out of either wood or polystyrene, and with a few small air holes drilled into the sides.
The box should be ¾ full of sterile compost or soft soil to act as a good thermo-insulating substrate which the tortoise can bury into. (Microwaving the substrate beforehand will ensure its sterility).
The tortoise is then placed into this box and the lid sealed with strong tape.
This box containing the tortoise is then placed in a larger outer box, again preferably constructed from either wood or polystyrene, with some air holes drilled into the sides.
The gap surrounding the inner and the outer box should be filled with loose polystyrene chips, ensuring the air holes are not completely blocked.

ACCURATE TEMPERATURE CONTROL

Now that your tortoise is boxed up, you need to ensure that it isn't going to freeze to death or be woken up prematurely; Basically you need an environment that won't drop to 0*c or rise to 10*c.
Ideally you need to find a place with a fairly constant 4 or 5*c. ...... THE FRIDGE!!!!!

If you're very lucky you may have a space in something like a brick garage where the temperatures are always within these parameters.  A thermometer with a minimum/maximum display is an essential tool to have for locating such places. However, for the most of us the only place around the house to offer this environment is the domestic refrigerator, and its the refrigerator method of hibernation I would urge you to adopt. They are great at keeping constant temperatures. Most are factory set to 4*c as standard. They are safe and predator proof. All in all they are ideal sleeping quarters.

NOTE; although tortoises require a very minimal amount of air whilst they hibernate, they do need some obviously.  As fridges are completely air-tight it is essential that the door gets opened at least once or twice a week for a few seconds just to allow a circulation of fresh air.

A thermometer should also be placed next to your sleeping reptile’s box so temperatures can be periodically checked.

SUGGESTED HIBERNATION TIME SCALES

new born hatchlings - 0 weeks

1 year old tortoise - 3 weeks

2 year old tortoise - 6 weeks

3 year old tortoise - 10 weeks

4 year old tortoise - 16 weeks

5 year old upwards- 22 weeks

Underweight tortoises or a tortoise that has had a recent illness should NOT be hibernated. Instead it should be artificially housed and heated until the year after.

AWAKENING PROCEDURE; heat and water!

When it's time to wake your tortoise you should follow the following procedure.

Immediately after awakening let your tortoise acclimatise to room temperature for around an hour or so, then place it under full "summer" conditions, i.e. under basking lamps, heat, etc.
After the tortoise has had a couple of hours basking under a heat lamp place it in a tub of warm shallow water for approximately 10 minutes.
 This will allow the tortoise to rehydrate through drinking and encourage it to flush out it's stored up uric acid compounds.
Water is far more critical than food for the first few days so continue to give baths two or three times a day for the first seven days.

Keep the air temperature in it's enclosure higher than normal for the first two weeks, including night time temperature, this is to ensure it doesn't try to go back into hibernation again.

Feeding should commence within a day or two. If your tortoise hasn't eaten within five days then there is obviously a problem and veterinary help should be sought

THE BENEFITS OF HIBERNATING

All hibernating species (including the majority of the Mediterranean species) are naturally biologically programmed for an annual rest period. It ensures that tortoises are not continually eating for 365 days a year and so encourages slow natural growth.

To artificially keep tortoises awake all year round would increase the annual food intake way past the norm. This would lead to abnormal growth rates, which in-turn leads to thickened keratin levels, lumpy scute formation, spinal deformities, spongy bone formation, etc.

It would also put an immense strain on the animal's renal system as urate production would be considerably increased, this leading to kidney or bladder stones and eventual death.
 There is also the phenomenon of suppressed breeding performance of animals which aren't hibernated; in particular sperm count is considerably reduced.

Therefore, if you want healthy tortoises make sure you hibernate them and hibernate them correctly!