Indeed, of course, in Keats’ time there were not all that many tortoises kept in the UK. But now the situation has changed markedly. Years of importing tortoises from the Mediterranean has built up a substantial population in this country, and unfortunately diminished the population in the wild to the extent that several species are endangered in their native countries.
In the wild, tortoises hibernate for only a month or two, but in this country hibernation may last for up to 7 months, and sadly many tortoises fail to wake in the spring. Most fatalities occur either near the beginning, or at the end of the hibernation period. But don’t despair, you can certainly improve your tortoise’s chances, by a few simple measures.
In order to survive hibernation in good condition, tortoises need to have built up sufficient reserves of body fat, which in turn stores vitamins and water. If these reserves run out too soon then the animal’s body will begin to use up the fat contained within the muscles and internal organs, leading ultimately to death. Therefore your tortoise requires a good and healthy diet through out the summer months: 20% green vegetables, 10% fruit, 45% weeds and grass and 5% mineral-vitamin supplement is ideal for Mediterranean tortoises. Meats such as dog and cat food should never be fed, as they damage the liver and kidneys.
The best way to check if your tortoise is fit to hibernate is to have your pet examined by your veterinary surgeon in a ‘pre-hibernation check’. The vet will weigh and measure your tortoise, examine its eyes, nose, ears and look inside its mouth for signs of disease, and assess the level of stored fat. If your tortoise is underweight, or in the first few years of its life, over-wintering it in a heated vivarium is safer option than hibernation.
Provided your tortoise is up to weight and no other abnormalities can be detected, then you can start to prepare your tortoise for hibernation.
Very many tortoises die each year because owners attempt to hibernate them whilst they still contain undigested food matter in their intestines. It is natural for tortoises to gradually reduce their food intake as the autumn approaches, but it takes a full 4 – 6 weeks for the food last consumed to pass completely through the gut. So the first thing to do, is wait 4 – 6 weeks form the last meal.
Having decided if and when to hibernate your tortoise, the next question is ‘how?’
Place your tortoise inside a small cardboard box, ideally allowing for a couple of inches of insulation material all around – shredded paper is ideal – straw should be avoided as it can harbour mould spores. Next place this box inside a larger wooden or more substantial cardboard box – a tea-chest is absolutely perfect. Again the inside of this should be lined with shredded paper or polystyrene chips. The double box system allows a hibernating tortoise some movement, without the risk of moving to the edge of the box, where it could easily freeze.
Where to place your hibernation box depends on the temperature. The critical temperatures are a maximum of 10 °C (50 °F) and a minimum of 0 °C (32 °F). Too hot and your tortoise will use up its body reserves too quickly and die, too cold, results in blindness as the eyes quite literally freeze solid, and brain damage. The easiest way to check temperatures is to obtain a maximum-minimum reading thermometer from any garden or DIY shop, and check it regularly. An ideal temperature for hibernation is 5 °C - so if you have an old fridge this is perfect! Wherever you decide to place your hibernation box, make sure that your tortoise will not be at risk from rodents.
Once you've got your tortoise successfully into hibernation, the next thing to do is check it at regular intervals. Most healthy adult tortoises loose 1% of their body weight each month during hibernation. A tortoise which is loosing weight too fast may die, so weighing your pet once a month could save it! If, when checking your hibernating tortoise, you notice that it has urinated, take it out of hibernation immediately as dehydration is likely to occur.
If you would like further information about your tortoise's health and hibernation, please feel free to contact the practice.
For more information contact:
British Chelonian Group http://www.britishcheloniagroup.org.uk/
The Tortoise Trust http://www.tortoisetrust.org/