Tortuga Gazette 27(10): 8-9, October 1991

To Build a Pen

by Dorothy M. DeLisle

The advantages of keeping herps outdoors are many. They include lower maintenance, excellent ventilation, and access to unfiltered sunlight. Not only is the last believed important for vitamin D synthesis in reptiles (especially chelonians), but it has been well documented to have positive behavioral effects. In many situations, outdoor space is much less limited than indoor space. Thus, outside vivaria tend to be larger, which helps to reduce stress on the animals and allows for more natural behavioral interactions.

Only the most adverse of climates prohibit the keeping of herp species outdoors. The exact list of species which can be successfully maintained outside does, of course, depend on your precise geographical location. Sometimes two locations only a mile apart will have such dissimilar climates that the list of species suitable will be different for them. This is especially true as one moves inland away from the coast or up in altitude. Some areas may be suitable for outdoor housing of certain species only during a particular season; the remainder of the year they must be kept indoors. The list of species suited to a particular area can be expanded by such micro-habitat alterations as providing more extensive shade, a misting system, heated shelters, and chilled pools, etc.

An indoor cage is within a room, which is within a building, and an animal living in it has three levels of confinement. Outside, there is usually only one level of confinement, the vivarium itself. Thus, it is especially important when maintaining animals outdoors that the enclosure be made escape-proof.

If your locality has a lot of beasties that could potentially prey upon your captives, or if the captives are extremely athletic, it may be necessary to completely enclose the vivarium, aviary style. However, in many instances, an open pen will be sufficient. It is the building of such pens with wire fencing that the remainder of this article will concentrate on.

After having decided upon the dimensions of the future pen, the next consideration is the type of wire fencing. In order of strength, one's choices range from screen to hardware cloth to poultry mesh to sheep wire to chain link. Screen is universally unsuited as primary fencing wire; it damages much too easily. Chain link is excessive except for the largest of species; a giant tortoise is capable of going through anything less.

Normally, the thicker (stronger) the wire, the larger the mesh opening. Thus, a fencing of sufficient strength to retain an adult may have mesh large enough to allow the passage of hatchlings. Anticipate the appearance of hatchlings and design their containment into the pen. If there is no one wire that will contain both adults and neonates, then you will have to lay a secondary small mesh over the primary fencing, or as recommended by many turtle keepers, run a board along the base inside the pen. A board will serve the further purpose of providing a visual barrier which in some instances is beneficial in preventing rubbing against the pen side, or the inhabitants getting head or limbs tangled or injured by the wire.

In the U.S., wire mesh comes in widths of whole feet. You can save yourself a lot of time cutting up wire and generating sharp edges by having the heights of your fences correspond to the pre-sized widths of the fencing.

No turtle or tortoise requires a tall fence; three feet is usually more than adequate. A low fence has the advantage of allowing the keeper access to his charges from all sides of the enclosure. One need only lean over to pick up an animal or put down a food dish. However, low fences should not be used when certain predators (including humans and dogs) are a potential problem.

Even to turtles, excessive height poses only minimal deterrent to climbing up and over a fence. Stinkpots (Kinosternon odoratus), wood turtles (Clemmys insculpta), Pacific pond turtles (Clemmys marmorata), and a few other species have all been known to escape by climbing straight up and over six foot fences! Even fairly clumsy species can climb up a corner. Installation of a climb barrier is an effective deterrent. Indeed, climb barriers should be used to surround all pens containing climbing species and across the corners of all other pens. Remember to plan for the unexpected neonates who are often much more adept at climbing than their cumbersome parents.

Rather than using post supports, a stronger and more permanent fence is obtained by attaching the wire to rectangular frames which form individual fence sections. These sections are then fastened (bolted) together. They can be easily disassembled to change the dimensions or location of the pen. A frame made of "2 x 2" wooden rails is usually sufficient.

As no one wants to be constantly rebuilding fences, they should be built for permanence. By far, the most permanent wood is pressure-treated redwood, but even this should be painted. Although less strong, fiberglass screen does not rust like metal screen. Galvanized metal is more permanent than none galvanized, but less permanent than vinyl coated wire which is by far the best choice.

Although hand saws are adequate, table-saws usually give a straighter cut. This allows a tighter fit of the frame corners and thus stronger joints. Paint the wood before assembly so that all surfaces are coated. Any damage to the paint done during assembly can be covered with additional paint as can the joints to give them added strength.

When attaching the wire to the frame, first fasten down the corners but keep it loose as they will most likely have to be removed as the wire is worked flat. Make sure that the wire is in place along the entire length of the frame and keep checking for this during the next steps. Working from the center out, fasten down the wire along one of the narrow sides. Then, fasten it along the long sides of the frame alternating between the two sides. As you staple (or tack), try to do it at an angle so that you are constantly pulling the wire taut. Try to get the wire as flat as possible while doing this, pushing down on its center. After you have finished all but a couple of inches of the length, fasten the remaining width, again from the center out, then finish off the length. I prefer not to cut the wire from the roll until I an ready to fasten down the final side; this eliminates errors in cutting to size.

Many people make the mistake of stapling around the frame in a continuous circle; this usually results in a "bubble" in the wire as one approaches the end of the circle. If you used a stapler, you should use a hammer where necessary to make sure that all the staples are all the way in. Also hammer rough edges so that they lay flat against the frame.

After the wire is tacked down, use liberal amounts of paint to cement the wire to the frame as both staples and tacks will come loose. Furthermore, paint helps smooth out any sharp edges you might have. If you were foolish enough not to choose vinyl coated wire, you should consider painting the rest of the wire to give it longer life. It is actually an easier task than one might think. The manufacturer of the paint I use recommends galvanized wire be aged six months before being painted. Thus, you might want to purchase your wire well in advance of building your fence.

A trench should be dug along your pen perimeter, and the bottom of the fence frame sunk into it. The depth of the bury will depend on the burrowing propensities of the species to be contained. Six inches is good for non-burrowers. A large bail of hay in the center of the pen will minimize or even eliminate ground burrowing in many species such as Russian tortoises (Agrionemys horsfieldii). When in place, attach the frame sections to each other. Although they can be nailed together, they are more easily disassembled if holes are drilled and bolts inserted. They also stay together tighter this way.

The gate should be measured after the rest of the fence is in place. First loosely assemble it and verify fit before proceeding to make a permanent assemblage. A diagonal crossbar on each side of the gate will add greatly to its strength. Remember to put a burrowing guard, such as a plank, into the ground under the gate.

Climb guards can be put on when the fence is in sections or after assembly and should also be put on the gate. A "1 x 6" plank makes a good climb guard. Nail or bolt the painted board onto the frame, keeping in mind how placement will affect future disassembly.

If you have not already done so, now add the habitat to the pen. (For major reconstruction, it is often advisable to create the habitat before one installs the fence.) Next add the turtles and/or tortoises and enjoy watching them enjoy their outdoor vivarium.