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HibernationFor most new or inexperienced tortoise keepers the dreaded "H" word often instills a complete blind panic, brought on by an irrational fear of accidentally killing their beloved pets. Infact, if this had still been the 1970's I would agree that most tortoises definately 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 effect the tortoise's health..... The plusses of hibernating far outway the minuses of not doing so as you will see as you read on...The common mistakes made by most people 30 years ago (and unfortunately still a 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 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 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) - 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 inside the animal's gastrict 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) A tortoise has an inbuilt mechanism which tells the tortoise to wake up when the surrounding temperature reaches 10*c. In their natural environments they will have burried 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 it's 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 it's supply and will be lifeless on awakening. Only immediate hydration therapy with a glucose solution will then stop the tortoise from perishing. (C) A fairly obvious one this ! ...Tortoises subjected to temperatures of 0*c or below will literally freeze to death. Even in the best cases the tortoises normally end up being blind due to the fluid in the eyes freezing and causing irrepairable ocular damage. (D) Another hopefully obvious one, but still this was responsible for many many chelonia deaths. 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, oportunistic hedgehogs which awoke before the tortoise did, ants, birds etc. (E) 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 escalated 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 were considerably escalated when the tortoise was also hibernated at incorrect temperatures. (F) Is self explanatory. With the above typical hibernating mistakes identified and the explanations as to "why" given , 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 periodAs already mentioned, any food left in the stomach of a tortoise when put into hibernation will simply rot, so the correct measure to take is to ensure that your tortoise's stomach is completely empty. Completely starve the tortoise prior to the hibernation period. The starvation period should be 7 days for tortoises up to 1 year old, 10 to 14 days for tortoises between 2 to 4 years old and 21 to 28 days for tortoises older than 4. If a tortoise is kept outdoors and has ready access to a food supply, don't worry as you'll find that the tortoise will naturally start eating less and less as the colder days draw in until it stops eating altogether. If housed indoors for whatever reason then simply wind down it's food intake over a period of a couple of weeks and then begin the designated total starvation period applicable to the age of your tortoise. Although a tortoise should have no food inside it's stomach it should have a full bladder, so regular bathing should continue throughout the winding down and starvation period to ensure adequate hydration. Temperature controlNow that your tortoise has been emptied of any food content you need to ensure that your tortoise isn't going to freeze to death or be woken up prematurely - you need an environment that won't drop to 0*c or rise to 10*c. 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 minimum/maximum garderner's thermometer 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! These are usually within the safe temperature guidelines but be sure to check with a thermometer first. Which ever place that you decide will suit the needs best you must ensure that it is safe from any possible predation and opportunistic theft. Then place the tortoise in a tightly fitting box (preferably plastic to prevent escape from clawing through the sides) containing soft loose soil or compost, of which it should be surrounded. Then place this box in another larger box containing polystyrene chips, as these make an excellent insulation buffer. (Although tortoises need very little air when hibernating they do need some, so ensure that your boxes are not air-tight) The boxes complete with tortoise can then be placed in it's designated hibernating quarters. If you are undecided about where to hibernate your tortoise may I strongly suggest the fridge, as I truly believe this is by far the safest and most effective method available to us. Providing the fridge door is opened for several seconds daily it will ensure enough air supply, for fridges are otherwise completely air-tight. Suggested hibernation time scalesnew 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 until the year after presuming they are then fully fit. Awakening procedureWhen it's time to wake your tortoise, or if it has woken itself then you should follow the following procedure.Immediately after awakening let your tortoise acclimatize to room temperature for around half an hour then place it under full "summer" conditions, i.e. under basking lamps etc. After about an hour place the tortoise in warm shallow water. This will allow the tortoise to rehydrate and encourage it to flush out it's stored up uric acid compounds. Continue to give baths two or three times a day for the first seven days. Keep the air temperature in it's encosure 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 vetinary help should be sought, although obviously this should not ever be the case if the above hibernation guidelines are followed. The benefits of hibernatingAll hibernating species like most of the Mediterranean group are biologically programmed for an annual hibernation 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 would increase the food intake to at least double the safe amount, this would lead to abnormal growth and cause metabolic bone disease, leading to lumpy shells, spinal deformities etc. It would also put an immense strain on the animal's renal system as urate production would be extremely increased, this leading to kidney or bladder stones and eventual death. There is also a phenomenon of supressed 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 ! NB. All the above advice is strictly for Mediterranean hibernating species, not for any other species of tortoise.
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