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Many species of tortoise kept as pets in the UK would hibernate throughout the winter in their natural habitat. Hibernation involves reducing the metabolic rate and temperature of the body so that it has a reduced energy requirement and can survive long periods when resources such as food are hard to find. 

The reptile community is currently divided in their opinion as to whether pet tortoises should be hibernated. Some take the view that hibernation is natural and, since tortoises do tend to slow down in the winter months anyway, we should let them hibernate just as their wild relatives do. Others feel that there is no need for a tortoise to endure the stress of hibernation because in captivity we can provide light, warmth, water and a constant supply of food during the colder months. 

In this article, we will help guide you on whether your tortoise is suitable for hibernating and – if you decide to hibernate them – advise on how to make the process as safe as possible.

Which species of tortoise hibernate?

Not all species of tortoise hibernate so it’s important that you first work out what species you have and thus whether or not they should be hibernated. If you are unsure, please speak to an experienced vet or a tortoise specialist.
Mediterranean tortoises DO hibernate and these include:

  • Spur-Thigh (Testudo graeca)
  • Hermann’s (Testudo hermanni)
  • Horsfield (Testudo horsfieldi)
  • Marginated (Testudo marginata)

Leopard tortoises (Stigmochelys pardalis) and Sulcata tortoises (Geochelone sulcata) are examples of species that DO NOT hibernate.

Some species occur in the wild over large natural ranges, so that some of that species will hibernate whereas others at the warmer end of their natural range will not.

Is my tortoise a good candidate for hibernation? 

Hatchlings (tortoises that have hatched during the current year) should not be hibernated as they will not have enough reserves to survive. 

If you have only adopted your tortoise this year, it is not advisable to hibernate it. 

Any tortoise that has been unwell during the year should also not be hibernated. Tortoises need a good fat reserve and should be as fit as possible if they are to survive a hibernation period. 

For the Hermann’s tortoise (Testudo hermanni) and the Mediterranean Spur Thigh tortoise (Testudo graeca), the Jackson ratio graph can be used to guide us on whether the tortoise is of a suitable weight-to-size ratio for safe hibernation. This involves comparing the length of the plastron (the bottom half of the tortoise shell) with the weight of the tortoise. 

Only hibernate tortoises that you know are fit, healthy, free from underlying health problems and are in good body condition.

How can I prepare my tortoise for hibernation? 

Ideally, your tortoise should have a pre-hibernation check-up with a vet to make sure it is well enough. This may involve a clinical exam alone, but other recommended tests include a faecal sample to check for internal parasites.

It is very important that tortoises undergo a pre-hibernation preparation period to ensure they are ready. The two main aims of this are (a) to ensure the tortoise is well hydrated and (b) to make sure the gut is emptied completely, as any food left inside the tortoise will rot during hibernation. 

Large tortoises (over 2kg in weight) will need a month of fasting, whereas small tortoises (less than 1kg) can be fasted for 2 weeks before they are hibernated. During this period, the ambient temperature should gradually be dropped till it reaches 10 to 15oC. The tortoise should also be bathed several times a week to aid hydration and encourage defecation to empty the gut. 

Remember to note down the weight at the beginning of hibernation.

How do I hibernate my tortoise?

There are three main methods that people use to hibernate their tortoises:

  • Underground

Some people allow their tortoise to hibernate themselves in the garden or greenhouse, letting the tortoise dig a hole and bury itself underground. The big issue with this is that it is exceedingly difficult to monitor the tortoise during hibernation. They can suffer damage from freezing temperatures and are susceptible to rodents and other predators.

  • In a box

Tortoises can be hibernated in an insulated box which is often left in a shed or garage. It can be difficult to regulate the temperature with box hibernation; it may drop below freezing in mid-winter, leading to permanent frost damage including blindness. Rodents can easily chew through boxes, their bites causing severe, life-threatening damage to the tortoise’s legs and shell.

  • In a fridge

This method of hibernation has become popular with many tortoise-keepers as it allows for close monitoring in a safe and protected environment. Fridges are usually between 4 and 8o C, which is perfect for hibernation – drink chillers are particularly good. It is advisable to put the tortoise in the fridge in a separate, lidded container (with air holes) to prevent any contact with cooling surfaces. The fridge should be opened every couple of days to refresh the air.

How often should I check my tortoise during hibernation?

It is advisable to check your hibernating tortoise every 7 days as a minimum. Weigh your tortoise each time and record and monitor that weight. If more than 5% of the starting bodyweight is lost, you should wake your tortoise up from hibernation.

You should also wake up your tortoise if they urinate during hibernation, as this means they have lost a large part of their water store and risk becoming dehydrated. 

How long should I hibernate my tortoise? 

Hibernation should be limited to a maximum of 3 months for adults and up to 6 weeks for yearlings. Remember, hatchlings shouldn’t be hibernated at all.

How do I wake my tortoise up from hibernation? 

Remove your tortoise from its hibernation box and immediately begin bathing, at least once a day, to allow drinking and urination. Initially, correcting dehydration is more important than feeding. 

The tortoise should be placed in a warm environment and a heat lamp provided to allow for basking temperatures of above 30oC. Food can be offered after the first bath has been given and most tortoises will start eating on the day they are woken from hibernation. 

Tortoises should have urinated and started to eat within a week of coming out of hibernation. If yours doesn’t do this, it’s important to seek veterinary advice as soon as possible. 

Remember that the experienced vets at Vet on the Net can assist you with any questions or concerns you may have about hibernating your tortoise. We can also arrange for faecal samples to be submitted to a specialist laboratory as part of the recommended pre-hibernation check-up and can help to guide you on treatments that may be required.