The Maintenance and Breeding of Tortoises and Turtles in Cold Climates; a review of Housing methods employed by The Tortoise Trust
A C Highfield
In this brief abstract, I would like to address the problems we face when we set out to breed reptiles from hot climates in our own, very much colder climates. This is definitely a problem for us in Britain, and is no doubt even more of a challenge in Scandinavian countries. Possibly some of the techniques we have developed may prove useful here.
Firstly, we looked at the energy demands of keeping reptiles, and with large numbers of animals the energy required is substantial. The least efficient method is to rely upon multiple electrical heaters. These are expensive to install, costly to run and are subject to total failure in the event of disruption to the electricity supply. In winter, this could have serious consequences.
Heating for large installations
Individual vivarium accommodation is the preferred method for small collections, but where many animals are to be accommodated it is both costly and inefficient. The Tortoise Trust's own collection, for example, relied for many years upon individual electrical vivarium heaters: the energy usage (and wastage) proved to be very considerable. A move to new premises presented the opportunity to design everything from the ground up, with energy conservation and efficiency high on the agenda.
The solution ultimately arrived at involved highly insulated main buildings, with polycarbonate twin-wall roofing for maximum natural light transmission and minimum heat-loss. A first building comprising 90 sq. m. (800 sq. ft) included both a humid tropical zone (for Red-foot, Hinge-back and similar tortoises) and an arid semi-desert zone (intended primarily for G. sulcata, G. pardalis and G. elegans). A second building with 70 sq. m. (625 sq. ft). floor area was then designed to provide additional accommodation for tropical semiaquatic turtles such as Geoemyda, Rhinoclemmys, Cyclemys and Heosemys species. Roofs were angled at 50* to allow for maximum solar gain (at our latitude of 52*N, the optimum angle will vary according to location) and black plastic water containers were placed against a rear wall to provide a heat store. Additional thermal mass was provided by constructing the internal tortoise enclosures from concrete blocks. These were painted dark brown to increase solar heat absorption during the day - at night they act as an impromptu storage radiator, drastically reducing overnight heating costs. For further design hints on such buildings, organic gardening and permaculture manuals are a good source of advice.
The main heating for our buildings is provided by a combination of under floor hot-water piping and a number of central heating radiators. These are both efficient and economical. The main boiler is oil-fired. This system has proved extremely cost-effective to install, and the running costs are less than 25% of those incurred with our previous electric heating system.
The under floor heating 'pads' were constructed by excavating a 20 cm deep pit and filling this firstly with 15-cm-thick insulation material and then overlaying this with cement containing embedded plastic hot-water heating pipes. This method has proved extremely effective and is greatly appreciated by all tortoises. Some pens were also equipped with wall-mounted central heating radiators. To improve basking possibilities, these were fitted at just above floor-level and a mound of earth positioned just in front of each radiator. The slope facing the radiator is self-selected by tortoises wishing to take advantage of the heat for basking.
The role that insulation can play in reducing heating costs and improving thermal stability should not be underestimated. Our own tropical house was lined with 40 mm thick aluminium foil-lined insulation sheets on all external walls and ceilings. This alone reduced heat losses by 40%. The floors of the tortoise sleeping quarters were also insulated from ground losses by 80 mm thick insulation sheets which reduced overnight heat pad losses to almost zero. Insulation sheet is a very useful material, easy to install, and in conjunction with polycarbonate twin-wall it offers many design possibilities for energy efficient reptile maintenance. With ingenuity, these materials can be employed in most vivarium and terrarium installations to great effect.
Design of breeding accommodation
The provision of satisfactory breeding and nesting areas is critical to the success of any captive breeding project. Very often, however, this aspect is overlooked. If properly implemented a good breeding pen and nesting site will have a dramatic impact upon the number of eggs and hatchlings produced, and an equally dramatic reduction in stress caused to the animals and consequential disease problems.
Some useful guidelines for the design of breeding accommodation are as follows:
Accommodation for Aquatic and Semi-Aquatic turtles
- Flat, featureless hard floor surfaces in breeding areas are associated with high rates of failure to obtain effective fertilisation. In the wild mating takes place on slopes, or on a natural earth surfaces which allow the female to raise her rear plastron sufficiently for the male to gain access. On a naturally undulating surface this is facilitated: on a flat concrete or grass floor, as seen in many collections, it is seriously inhibited. The larger the animals involved, the more important this appears to be. With Leopard, African Spurred, Galapagos and Seychelles tortoises it is vital that the mating area surface is adequately sculptured.
- Breeding areas require adequate cover for animals to retreat, and careful attention must be paid to stress and aggression levels. Females which are stressed may experience laying problems later. Provide plenty of space, and above all provide a few plants and hilly areas for animals to hide themselves. Exterior enclosure walls should be opaque; if they are transparent many animals will spend much of their time trying to climb either over or through them.
- Nesting areas should be raised, and preferably gently sloped. South-facing slopes and terraces are ideal. Flat and featureless nesting areas are associated with a high rate of egg retention problems. Nesting boxes should have an adequate substrate depth. For large tortoises a considerable depth of laying site substrate is essential. For Geochelone carbonaria, G. sulcata or G. pardalis at least 50 cm is required. More for very large specimens. Smaller species will often accept a substrate depth approximately equal to their own carapace length. If an adequate depth not is provided, this can easily result in aborted laying attempts and secondary complications. After many trials, we have found that providing each penned area with two separate nesting mounds is much preferred by the tortoises. Ours are made from a mixture of clay-type earth and sand, retained in position on three sides by surrounding timber logs. One side, gently sloped, is left open for easy access. A selection of plants is grown on the nesting mound, and the fine root structure of these greatly facilitates excavation of the nest chamber. In the wild, most nest sites adjoin similar root-infiltrated slopes. The extra element of choice allowed by providing more than one laying site in captivity definitely appears to reduce stress and facilitates problem-free nesting.
- One special technique has proved useful with several species, terrestrial as well as aquatic, where the female seems to be experiencing problems in locating a suitable laying site. In this situation it is worth removing her to a separate area with a good depth of substrate of the appropriate type and with a 100 watt reflector lamp suspended about 50 cm above ground level. The female should be disturbed as little as possible. After a day or two in this environment, many otherwise reluctant females will lay without further difficulty. We have observed that some tortoises and turtles will lay in the early evening if maintained under a basking lamp, so when working with a problematic female, it may prove worthwhile persevering beyond normal activity times.
Surface mounted ponds
For larger animals a solid fibreglass pond may be more suitable. These can often be purchased read-made from water garden supplies. The addition of a simple wooden framework will permit most designs to be surface mounted. Alternatively, a plywood framework, with suitable reinforcements, can be made and then lined with a standard butyl pond liner.
Another fast and effective method of constructing shallow (up to 200 mm deep) surface mounted ponds, either indoors or outdoors, is to employ standard medium-density concrete blocks as used in buildings to provide the perimeter framework and to overlay this with a good quality flexible PVC or butyl pond-liner. The pond can be finished by overlaying natural-effect capping stones around the edges to hold the liner in place. Fitted with a central basking platform and undergravel filtration, such ponds can be highly effective and are well-suited to many species of turtle.
If using ponds like these in winter out-of-doors, it is important that insulation is applied around the walls and base to prevent the water freezing solid. Such ponds are obviously only suited to tropical species if adequately heated and located in a warm indoor environment.
Shallow ponds for semi-aquatic turtles
Shallow ponds for semi-aquatic species are often far more difficult to design than ponds that are designed for entirely aquatic species. The main problem is that of water depth; these ponds are usually required to provide only a shallow depth, typically 75 to 150 mm. This severely limits the choice of filter system, many of which will not work at all unless there is a greater head of pressure. Efficient filtration is especially important in shallow water pools as there is less water volume than in larger tanks and biotoxin levels rapidly attain high concentrations. Because high light levels are also experienced right down to the substrate proliferation of algae and overgrowth of blanketweed is also a frequent problem.
At the Tortoise Trust, we experimented first with shallow sunken pools lined with butyl pond liner for our tropical and temperate box turtles. For a variety of reasons, these were not very successful. Firstly, they were a chore to clean out (drain holes being almost impossible to install), and we experienced serious problems in achieving adequate filtration of the small volumes of water involved. They were rapidly abandoned.
We finally arrived at a new design. This is constructed from marine grade plywood and is double coated with brush-on resin to completely seal it against any water penetration. It can be partially set into the ground but is equally satisfactory surface mounted. For filtration an under-gravel system driven by a submersible pump of the aquarium powerhead type is used in combination with an AquaclearÒ hang-on-side unit. The under gravel component provides high quality biological filtration, whilst the AquaclearÒ filter is loaded with activated charcoal to assist chemical quality. Because parasite levels, especially flagellate organisms, in this type of pool can present a real danger, we also circulate the water through a small ultra-violet steriliser before returning it to the pond. To achieve this a second submersible pump is required. To further enhance the water quality and overall habitat, some aquatic plants are also included.
This design is highly effective, attractive and very versatile in the sense that ponds of unusual dimensions can be readily constructed. To prevent too much terrestrial substrate such as leaf litter and bark mulch from entering the water, the slope leading to the lip of the pond is made from a 20 cm wide bed of medium-sized pea gravel.