Hibernation

 

 

This page is aimed at helping you in a basic guide to hibernation. New tortoise keepers think they are the only ones to worry about hibernation time but rest assured, you're not on your own. Even experienced keepers have a few nerves at this time of year.   Having said that, I feel that hibernation is a very important part of the life cycle of tortoises that would naturally hibernate in the wild.  Some believe that hibernation isn't necessary, especially if you don't intend to breed your tortoises, but research isn't conclusive enough yet to prove that to be true!  Stay on the side of safety and follow your tortoise's natural life cycle.  Another myth is that baby tortoises shouldn't be hibernated (until they are between 3-5yrs old).  Research (and experience) *is* conclusive enough to tell us that the myth is complete rubbish!  Wild tortoises hibernate from a very young age and have no choice, some of them only having hatched a few months previously.   Having said that, *all* tortoises should be assessed yearly before hibernation is planned and judged whether they are fit/healthy/heavy enough to do so.  Remember, not all species (and sub-species) of tortoises hibernate in the wild and therefore, you should be 100% sure of the species of tortoise you own.

 

 

 

planning

 

Successful hibernation takes thought and planning.  When your tortoises are outside enjoying the heat of the summer, you should be planning for the cold months of winter.  The most obvious concern is where you are going to hibernate your tortoise!  There are various methods of hibernation, the most popular being the "fridge method" and the "box method".  The box method is what the majority of long term captive tortoises have endured over the last 50 years and if you have a suitable environment for this, there is nothing wrong with it.  With modern day living, unheated houses and solid brick built outhouses are becoming a thing of the past and so the fridge method is becoming more and more popular with excellent results.  The fridge method is my preferred choice of hibernation.

 

 

BOX METHOD

If you have a solid outbuilding that is safe from frost and vermin, it's worth investigating it as a suitable hibernation place.  The best locations are those that are adjoined to houses which therefore retain some heat from the house walls.   Garages etc are good for this.  The key to success is to monitor the location with an accurate digital min/max thermometer, preferably the winter before you intend to use it.   The most important thing during hibernation is the temperature the tortoise will be at.  Too cold and you risk tissue damage to the tortoises eyes resulting in blindness and eventually death, too warm and the tortoise will be active enough to start burning up vital fat reserves but not warm enough to be fully functional.  This will result in a large amount of weight loss, post-hibernation anorexia and possibly death.  The guide for ideal hibernation temperatures is 5C (41F) although a degree or two either side of this is safe and these are the temperatures you should be aiming for during your search for a safe hibernation location.   If you have an outbuilding and after careful monitoring, have decided it's safe, the box method may be suitable for you.  A gentle heat source (such as a greenhouse heater or a tubular heater) can be wired into a thermostat which is then set to come on should the temps drop to approx. 3C (37.4F) and placed into the outbuilding for added protection from mother nature.

 

For the box method, you will need two strong boxes.  The outer box may be made of strong cardboard, polystyrene or wood.  The outer box acts as "housing" for the inner box that will contain the hibernating tortoise.   The outer box needs to be at least a few inches bigger all round than the inner box and will be packed with insulating material such as shredded paper (avoid hay or straw as they can harbour mould spores and damp).  If the temperature drops for some reason, the outer box will also act as insulation to the inner box therefore taking longer for the inner box to feel the drop in temperatures.  The inner box sits inside the outer box padded by the insulation.  Both boxes need to have air holes added even though a hibernating tortoise needs little oxygen.   The hibernating tortoise is placed inside the inner box (again packed with substrate such as shredded paper) and the lids of the boxes closed.  A min/max thermometer probe needs to be placed alongside the tortoise so that the temperatures can be monitored at all times.   The hibernation box can be wrapped with wire mesh (such as chicken wire) which will then guard against any hungry vermin.  The box can then be placed in your chosen hibernation spot and monitored throughout the winter months. 

 

 

FRIDGE METHOD

 

If, like me, you have no suitable outbuilding, then you should consider using the fridge method.  It sounds shocking and scary but think about it, you will have complete control (with careful planning) over the hibernation conditions therefore allowing your tortoise to have his natural sleep but without the risks that mother nature throws at us.  Lots of tortoise enthusiasts are using this method now with great results. 

 

Although some people with just one or two tortoises are successfully using the salad drawers in their domestic fridges, the ideal fridge to use is a separate larder fridge with no icebox compartment.  Over the last few years, small drinks chiller cabinets (often sold as promotional items with branded lagers) have also been used with success.   The most important thing is to be sure that the fridge temperatures are stable and again, this can only be assured with careful monitoring.    Be aware that a fridge in an outbuilding that is subjected to varying temperatures is likely to reflect those changing temperatures inside the fridge eventually.  Ideally, you need to place your fridge in a room in your house for it to function normally.

 

Once you have decided where the fridge will be placed, it's time to monitor the inside of it where the tortoise will be.   This is done using digital min/max thermometers with probes and ideally with an inbuilt alarm which will sound if the temps fall outside of the set parameters.  Measure the temps at different places inside the fridge because it will vary, and you need to find the ideal spot for the tortoise (5C or 41F).  An empty fridge will not be as stable in temperature as a full one and therefore adding lots of mass will help to keep the readings stable.  Fill the fridge with bottles of water or even bricks etc to keep the readings stable.  Whilst you are monitoring temps, its a good idea to place the hibernation box inside to mimic the time when your tortoise is in there.  Once you add things to the fridge, the temperatures will rise and take a while to fall and settle again so the "trial run" needs to be as near to the "real thing" as possible.  During the trial run, adjust the fridge thermostat (dial with numbers usually going from 1 - 6, the higher the number, the colder the temps) to find the ideal temperature of 5C (41F).  As you adjust the dial, the fridge will take some time to settle and stabilise (as much as 48hrs) and this is why plenty of forward planning is needed.

 

You can use various things to house the tortoise inside the fridge.  It can be something as simple as a cardboard box with air holes or something more sturdy such as a wooden box (just remember to have the box in place during your trial run).  The box doesn't have to be packed with insulation material because you will be controlling the temperature and therefore wont be needing any added protection.  Having said that, many tortoises seem more comfortable with some padding/digging material making them feel more secure.  You can use shredded paper, hemp (aubiose) or a sand/soil mixture for them to dig into.

 

It's also possible (for those that have larger numbers of tortoises to fit into a fridge) to place the tortoises directly onto the fridge shelves which are lined with either thick cardboard or towels.   If you are doing this, then some barrier such as cardboard or polystyrene sheets should be added to the back of the fridge to avoid the tortoises coming into contact with the parts of the fridge that naturally get some ice droplets forming on them.

 

An "under the counter" size fridge containing hibernating tortoises.  The back of the fridge is lined with cardboard sheet and the shelves are lined with cardboard and newspaper. 

 

Another choice is to find shallow boxes that fit exactly onto the fridge shelves in which you can house several tortoises per box.  Try your local farm shop, boxes like these are used to deliver fruit/veg to them.

 

I have used all of the above before and all have worked as well as each other.

 

Once hibernation time arrives and the tortoises are inside the fridge, the temps can be monitored daily for any changes.  The door to the fridge should be opened daily for air exchange or alternatively, you can run some plastic piping (rubber aquarium tubing) through the seal of the door.

 

 

OTHER METHODS

 

There are other methods for hibernation apart from the above such as using a cellar (they usually stay pretty stable in temperature) or "natural hibernation" which is where the tortoise digs down under the earth outside.  Natural hibernation is ok as long as you can be 100% sure that the tortoises are in a location (such as a greenhouse or cold frame) where they will be protected from frost and damp (preferably with some type of back up heating for when the temps. drop too low) and that they cannot become prey to hungry predators such as rats.

 

 

 

Hibernation Length

 

Another part of planning is to have a rough guideline as to how long you are going to hibernate for.  If you are using the box method (or natural hibernation method), this may be decided for you by the weather.  If we have a really warm spell during January, it might be enough to wake the tortoise meaning it has to be got up immediately and kept warm and feeding.  If you are using the fridge method, you will have control over the length of hibernation as the tortoise will be in ideal temperatures therefore keeping his system in its hibernation state.

 

As a rough guideline, a very young tortoise or a tortoise that has not hibernated before should be given approximately 8 weeks of hibernation.  If after this time, the tortoise is doing well with minimal weight loss, there is no reason why it can't be extended.  Adult tortoises can be given up to 14 weeks, again monitoring them weekly to make sure there is not too much weight loss.   You need to always be prepared to take your tortoise out of hibernation early should it need it, and therefore an indoor enclosure with adequate heating and lighting needs to be made available at short notice. 

 

 

 

 

Winding Down

 

It's very important that the tortoise's digestive system is empty of all food when it goes into hibernation but at the same time, that it's fully hydrated.  If the tortoise's stomach contains food during hibernation, it can rot inside it and eventually cause death.   Tortoises need to empty out for *approx.* 4 weeks prior to hibernating but must be given the opportunity to drink regularly.  When you are winding your tortoise down, it means *no food at all*, not just a little bit because he is looking at you with pleading eyes. 

 

Below is a weekly guide to winding down:

The tortoise is to be given *no* food during any stage of the wind down period, this is very important.   It is also very important that they are given ample opportunity to drink and are fully hydrated.  Bath your tortoise every other day which as well as hydrating him, will encourage him to empty himself out. 

 

WEEK 1

 At the beginning of the wind down period, tortoises need to have day length and temperatures that are approximately the same as summertime.  This will keep their digestive systems working fully and therefore pass any recently eaten matter through the system.   You may find, due to the weather, that they are slightly slower than they were in the summer but be prepared for some pleading looks.  DON'T give in! 

 

WEEK 2

During week 2, you can keep the temperatures the same as week 1 but in lesser quantities.  Therefore, you should be aiming to turn the heat/uv lamps on a little later in the morning and off a little earlier in the evening.  This will simulate their shorter day lengths in the wild.   Towards the end of week 2, make the "daylight hours" shorter still making it a gradual process.

 

WEEK 3

By week 3, you will find that your tortoise is coming out from his hiding place less and less.  You can now leave the basking lamps off completely and just have a gentle background heat available such as a tubular heater if in an outbuilding or your central heating if it is inside the house. 

 

WEEK 4

During the beginning of the final week, any background heat should be turned down to a bare minimum.  You will probably find that the tortoise is not coming out at all now and is inactive.  Towards the end of this week, give your tortoise its final bath (not warm enough to stimulate him) and make sure he is thoroughly dried.  Place the tortoise in the box that he will be hibernating in.  Place the box in a cool place such as an unheated room or a safe outbuilding.  If you are using the fridge method, this will cool him down further which will more closely match the fridge temperature.  At the end of the 4 weeks (and as long as he isn't still passing anything in his bath water), the tortoise should be ready to go into its hibernation quarters.  Make sure you weigh your tortoise before it goes into hibernation. 

 

 

 

 

Monitoring

 

The tortoise will need careful monitoring during his hibernation period.  This will alert you to anything going wrong that may need action.  Thermometers should be checked at various points in the day and a physical check and weigh in will be needed weekly.  A tortoise's "hibernation stance" varies between individuals.  Some will tuck their heads and limbs tightly inside their shells while others will have all their limbs hanging out.  When making the checks, try and do it at a time of day when it's coolest to minimize the risk of disturbing it.   A couple of minutes observing and weighing your tortoise shouldn't disturb him in the slightest.  Check that its cloacal area is clean and dry and there are no signs of defecation or urination.  If a tortoise urinates during hibernation, it will need to be got up as it could easily dehydrate.  Also check that the nares are dry and clear.  Weigh your tortoise and keep a record of how its weight is changing.  A safe guideline is that your tortoise shouldn't lose more than 1% of its total body weight per month.  You will probably find that during the first couple of weeks, is when it will lose weight more, this is due to him settling down and perhaps being a little active.  If he does lose more than 1%, don't panic but monitor the situation as you may well find that a few more weeks down the line, he won't be losing any and therefore it will average out his weight loss over the total period.   

 

 

 

Waking Up

 

Wake up time will be guided by the weather, your decided hibernation length or by a tortoise that has lost too much weight etc.  I suggest waking them up early in the day which gives them the rest of the day to heat up and hopefully begin drinking and eating.  Make sure you have the tortoise's enclosure up and running with heat/uv lamps.  

 

Take the tortoise out of its hibernation location but still inside the box.  Place the box in a heated room for a little while and the tortoise will soon begin to stir.  As soon as the tortoise is waking up, take it out of its box and place it under its basking lamps.  Heat and light is the only thing that will stimulate him properly and get his system up and running again.  This is very important, a tortoise who isn't warm enough will not get going properly and then will have problems beginning to feed.  Once the tortoise has had a good warm up under its basking lights and is becoming more active, give him a nice long warm bath.  He needs the opportunity to flush out the toxins that have built up during hibernation and replenish his water supply.  You may find that he doesn't drink straight away but continue with warm baths until he does.  Drinking is far more important than eating in these first few days.   Once the tortoise is active (and has hopefully drunk) offer him some food. Some tortoises eat within half an hour of getting up, others might take a few days.    Continue with the warm baths daily for at least a week and then they can be gradually cut down. 

 

Remember that to keep his system functioning normally, supplemental heat and light are needed. A cold tortoise will not eat.