An outdoor tortoise will usually self-hibernate in early November depending on the weather. Food should be withheld from mid-October or even earlier if the tortoise has access to natural forage. This is to stop undigested food from decaying in the tortoise’s stomach whilst in hibernation as any undigested food could cause a bacterial infection or asphyxiation.
An outdoor tortoise may choose its own spot to hibernate in the garden or in its habitat; they tend to like dry areas and will often burrow into the soil. The problem with this is that they may not find a suitable spot and could be potentially at risk from predators such as rodents, flooding, and shell rot due to the bacteria in the soil.
Owner intervention is usually required to hibernate a tortoise safely and there are lots of different methods:
Place a large deep container into the ground and fill it with the soil making sure the container is covered to keep the tortoise dry. This method is good and allows the tortoise to change its position in the soil depending on the soil temperature, but the tortoise may still be exposed to very low temperatures.
A suitable place to hibernate a tortoise is in an unheated outbuilding. Place the tortoise in a small box, that is big enough for them to move about in. This can be wooden, cardboard or polystyrene, then fill with a suitable insulator, which can be polystyrene chips, shredded newspaper or straw. The box should need air holes in the lid. This box then needs to be placed in a larger insulated box, ensuring all sides of the inner box have insulation around them, some air holes should be made in this box too. During hibernation, the tortoise will dig down to the bottom of the box. The insulation material does not keep the tortoise warm but acts as an insulator to protect him should temperatures drop outside of the box.
It is important to monitor the temperature of where the tortoise is kept to ensure it is suitable. This can be done using an indoor/outdoor thermometer. An ideal temperature is between 5-6°C, anything lower than this and they run the risk of frost damage. Anything above 10°C and the tortoise will awaken. Before hibernation, the tortoise must be weighed as the weight will be lost during hibernation. Tortoises lose roughly 1% of their body weight per month during hibernation. It is also very important to check their weight whilst in hibernation. If they lose between 8 – 10% of their body weight, they must be awakened because once the fat reserves have been used up, the tortoise will start to break down muscle and other body proteins which can lead to post hibernation anorexia. It is also normal for a tortoise to move during hibernation if they sense a change in temperature. This is not a sign they are ready to be taken out of hibernation and they should not be removed until it is warm enough to do so. Tortoises tend to come out of hibernation naturally when temperatures rise above 10°C. When it is time for your tortoise to come out of hibernation offer them a shallow warm bath, this gives them the chance to drink and will encourage them to urinate, healthy tortoises tend to drink within a week and eat within 2 weeks if they are not, please speak to your veterinarian.
Dandelion and Watercress leaves are naturally high in calcium which is vital for healthy bones and shell development. Lettuce, Nasturtium, Sow Thistle, and Clover can also be given as they contain a level of calcium too. Cauliflower, Brussel Sprouts, and Broccoli can be given but no more than 10% of the total diet as they contain substances called goitrogens which can induce low thyroxine levels. Cucumbers and courgettes are good sources of water. Vegetables such as grated carrots, rocket, lamb’s lettuce, and kale can be given. Flowers can be given but do be careful as some are poisonous, Violas, Pansies, and Hibiscus flowers are taken well.
Beans and Peas can be given but only in very small quantities as they contain phytic acid which will bind with calcium into a form the tortoise is not able to absorb.
Fruits are eaten by tortoises in the wild to supplement their diets if no other food source is available, some fruits e.g. Bananas can cause stomach upsets, so it is recommended not to give fruit daily and to feed no more than 10% fruit in the total diet.
Supplements can be given, there are many available calcium supplements which are often combined with multivitamins, if you decide to use a supplement ensure it is suitable for reptiles and contains vitamin D3. Vitamin D3 is essential in the absorption of calcium into the body, this vitamin is essential if your tortoise is not living outdoors as vitamin D3 is created during sunlight exposure (UV rays).
Millpledge supplements such as Vetcal Pro-Gel and Vetamin & Zinc can be added to their diet to boost any deficiencies and ensure your tortoise remains strong and well.
Pellets can be given and contain good levels of calcium and vitamins however the fibre levels of pelleted food are often quite low, adding leafy greens to the pellet mix will increase this. Pelleted foods should not be used exclusively but can be useful when fresh foods are not available.
Spinach, Rhubarb leaves and Daffodils should not be given as they contain oxalic acid which can irritate the gut lining and can trigger bladder stone formation, also it will bind with calcium into a form the tortoise is not able to absorb. Flowers can be given but be careful when offering flowers as some may be poisonous. Meat in any form especially tinned dog and cat food should not be given as the protein, fat and vitamin levels are too high and can lead to liver and kidney disease.
Tortoises are grazers and tend to eat small amounts at one time, in the wild, they tend to bite off small pieces and move on, you may find when you have presented your tortoise with a pile of food they only eat a small amount and then walk over it, sometimes defecating or urinating on it, this can be frustrating so where possible try to feed a small amount twice a day to save on waste. Tortoises like to be free to roam so allowing them to graze on the lawn and borders with only a minimum of dietary supplementation is usually best, a good sign is if their faeces are well-formed and dark. Runny faeces can be a sign of parasitism but is more than likely due to low fibre in the diet.
Ref: Jepson L, 2006, Mediterranean Tortoises, Surrey, Interpret Publishing.