Terrapin and turtle information and care sheets

Health, Hibernation and Habitat

Author: Roman Muryn

13 August, 2011



Last year I wrote about making ponds and keeping North American turtles outside in the UK. My interest came about as a result of the appalling strategies that we in the hobby adopted in trying to manage the burden of unwanted animals that resulted from the consequences of the Mutant Ninja Turtle craze. This included hundreds of animals being shipped from a country (UK) where they cannot breed to a country (Italy) where they can breed if they escape.

Since the start of that craze and up until the present, millions of animals have been imported into this country, most of which have ended up dead. The law that was passed in 1997 to prohibit the import of Red Eared Sliders was largely circumvented by the import of their look alike cousins the Yellow Belly Slider and the Cooter. However many thousands have survived often as a result of caring and informed homes. Human lives are transient and circumstances change, often resulting in the rehoming of the pet turtle; too often the pet cannot be rehomed and is released into a local pond.

This is illegal.

The majority of animals thus released are of the Slider and Cooter variety. These animals when adult are mostly vegetarian and have a similar diet to carp. They do not however, have the same metabolic rate as carp and those that have kept turtles with carp know that the fish always gets to the food first. In the wild their dietary needs are not great, vegetation, snails and invertebrates. Maybe part of the solution to these unwanted pets is to keep them in outside domestic ponds provided the pond is secure and they can't escape into the wild.

In previous articles I have described pond design and have outlined which animals could do well outside in a UK pond. There is a proviso though, they have to be healthy and their environment has to be suitable - this is harder that it at first seems and attrition rate is very high if factors are unsuitable. Death rates can be up to 50%.

Since writing those two articles last year more information has come to light as a result of scientific study and this article is really an attempt to stitch up all the technical threads and apply them in a hobby context. Very few if any hobby books describe the hibernation issues in detail and I hope I can fill in a few information gaps.

I have titled this article as Health, Hibernation and Habitat



Let's start with the basic health of an animal; imported animals have never had to go through a natural selection process as they would in the wild. Contrary to popular opinion breeders are meticulous with their breeding regime and a very high proportion of their hatchlings survive. Yet in the wild a very small percentage of all eggs laid get transformed into hatchlings and predation by raccoons, skunks and human impact takes its toll. Once hatched they then run the gauntlet with other predators, now including fish, birds and of course humans. Any animal vaguely unfit is removed by nature, not so in the turtle farms.

During rearing they will have been kept in clinical conditions with no contact with natural pathogens and protection offered by anti-biotics, so no natural developed immunity has been developed. When introduced into the wild they will be susceptible to new pathogens - a bit like the spread of small pox with humans.

The young animals in nature have specific and balanced dietary needs along with the availability of natural sunlight and clean water. Regrettably, when bought for not very much on a whim, the animal will not fare well. All too frequently the result is a dead animal or an animal that has grown unnaturally, often with a deformed shell. If its body or organs have not have grown properly then it simply will not have all the tools to see it through hibernation as we shall see later.

I was fortunate enough to have visited Elmar Meier in Muenster Zoo and part of the discussion centred upon stress and the effect it had on the immune system; our own Kevin Eatwell echoed him in another similar discussion. This part of husbandry gets too little attention but the reader should be in no doubt that a stressed animal is extremely susceptible to falling sick. Some diseases such as herpes are always present but only surface when the host is under stress. Shingles in humans is a good parallel example. I have rehomed animals that have had real problems with introductions to the outside after prolonged imprisonment in a glass box. One little box turtle would not eat for months and only then when I put it into a small enclosure, it's taken 3 years to recuperated him.

The move from an aquarium to an outside world pond therefore does carry significant risk for all sorts of reasons.



There is a real dearth of plain speaking about turtle hibernation and it's a tricky subject to tackle as its littered with Old Wives Tales and wisdom borrowed from other hobbies.

There are many elements that contribute to a successful hibernation and each stands on its own by the end, the reader will see how they join up.

I hope I have shown that to go into hibernation a turtles physical condition is so important. All aspects of the body contribute to the survival strategy. Animals raised in glass prisons that have not developed properly may well not have the right tools to survive winter.



In the wild turtles select their own place for habitation and hibernation. Females will remember where they were born and hence remember a potential nesting site, then over the years they will learn of locations that prove suitable for feeding and hibernation. Much of their knowledge is instinctive and mistakes of choice are paid for with their lives.

Read any of David Carrols books - his accounts of turtle migration as the seasons change are very telling. He talks of migration in spring to vernal ponds where there is plenty of easy food such as tadpoles. He talks of migration to breeding areas and of migration to other areas as food availability changes. In the wild they have to hunt for their food and learn where to find it with the seasons; in the domestic pond this will not be an issue, but their willingness to travel and explore will be. The garden must be secure as they are great climbers.

When winter comes they will not have a choice of location for the big sleep and the pond keeper must provide suitable hibernation conditions appropriate to the animal type kept. It will invariably be a riverine type.

From my understanding the riverine animals do take care that they have good oxygenated water but they also have to deal with water level changes. In the UK we think floods, however in northern USA the depth of winter brings months of freezing temps often less than -100c for weeks and weeks. Rain does not fall; snow does, several feet in fact. This acts as an insulator from the severe weather above the water. The temperatures in the water will be the same as we would find in the UK. During the winter period the water levels often drop and air gaps develop between water and ice.

Animals do hide themselves away as some predators still go about their business even in winter. David Caroll tells of turtles that have been found by otters with varying degrees of damage - its distressing reading.

The spring brings on the thaw and with that flooded rivers, animals then seek more sheltered waters.

Last year was a nightmare for many of us that hibernated turtles outside. Whilst my pond dwellers all did well generally, my riverine species were hit very hard. The ice stayed for nearly a month and as I don't have any pump system the inevitable anoxic conditions overcame some of my animals - mostly the big Slider females.

So finally the habitat too plays a part in the ability for the turtles to survive outside in the UK.


In conclusion

There is no doubt that most of the commonly imported North American turtles can survive in outdoor ponds in the UK. This is confirmed by the many thousands that have survived since the original Ninja craze over 20 years ago. With luck many have found suitable food and hibernation conditions.

It is regrettable that the turtles have been lumbered with a reputation of being killers of UK fauna. These omnivores will take insects and other invertebrates but they are too slow to catch a fish or even a young bird. They will take easy protein so dead animals will be eaten. If seen eating carrion they will of course be labeled as the killer.

I have many turtles outdoors in my ponds I have never seen one catch a fish; I have seen them catch tadpoles and newts. However at the end of spring I always still have masses of little frogs hopping about and I have all three species of newts in my ponds.

I think the domestic pond can be a good way of reducing the numbers of animals released into the wild ponds provided it is secured to prevent escape.


So what do they need?

As we have read turtles have many complex needs and just placing them in a pond does not mean it will be suitable. It is an assumption commonly made.

Turtles are ectothermic and need heat (infrared) from sunlight to raise their metabolic level in order to move and digest food. They need sunlight (ultra-violet B) to help manage and produce vitamins, the two sunlight qualities go hand in hand. Without sunlight they will simply not survive. Their pond therefore needs a basking area that has full sunlight for good parts of the day but especially around midday. That basking area should be private so they are not scared into the water frequently and a bit of wind shade will help too. They should be able to get into their area easily.

The pond should not be too deep, say less than 2 feet. This depth allows sunlight to penetrate allowing plant oxygen generation. It also helps to reduce build the up of anoxic water layers by water circulation due to wind.

The pond should have sloping sides so that animals can move about and get to the surface easily if they are cold stiff or in trouble through acidosis.

The pond should have as many oxygenating plants as possible. If snow falls, clear it off the ice above the plants and allow the sunlight back in.

I shall be using an aerator this year to add movement to the water. In USA with waters under anoxic threat, the State wildlife Rangers strap outboard motors to jetty pylons and really circulate the water.



If you want to read more get these two books first.


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