Added April 28 2001
SIZE MATTERS
Of all the reptile orders, only the Squamata (lizards and snakes) show such a huge diversity of sizes, from creatures as small as the palm of the human hand to giants up to 10' long or, in the case of the largest boids, even 30'. In practice, however, very small snakes are rarely kept in captivity as they are extremely secretive in nature, often being burrowers, and often hard to keep alive on the usual terrarium diet. This means that from a keeper's point of view, only lizards are likely to be offered in such a wide range of sizes.
This article looks at the advantages and disadvantages of the different sizes
of lizards. It is hoped that the reader will find it thought-provoking and help
him or her to make a better-informed choice when considering the acquisition
of a particular species.
The assumption in the guide is that the reader will conscientously follow the
rule of thumb for the size of terraria for lizards, which is usually that the
cage should be at least 2½-3 times as long (or, if arboreal lizards are
kept, as tall) as the snout-to-tail length of the lizard, allowing more space
per individual kept within the terrarium. Snakes may be kept in somewhat more
economical spaces, but certainly not lizards, particularly those species which
are very active or highly-strung.
Small lizards can be considered as those which are under a foot (12" or 30 cm) in length. This category would include virtually all geckos (including the deservedly popular Leopard Geckos, Fat-Tail Geckos and Tokay Geckos), with the exception of the Rhacodactylus giant geckos from New Caledonia which often reach 14". Many skinks, such as the beautiful Mabuya species, also fall into this category, as do the popular Brown and Green Anoles (Anolis sagrei and A. carolinensis), European Podarcis wall lizards and the smaller Cordylus species (the ones usually seen in the hobby, since the larger Sungazers are now virtually unavailable).
This size category could in fact be further subdivided into Small and Very Small. Very Small I would consider to be under 6" in total length: the lizards I have in mind here are mainly the smaller geckos such as Lygodactylus and the anoles. This size really means a "hands-off" approach, treating these diminutive but often beautiful creatures as display animals instead. The larger geckos, such as the Leopards and Fat-Tails, will tolerate some handling, but not too much. Again, they should be really be regarded primarily as creatures to be admired and watched rather than petted. Although this is a generalisation and much depends on the species (Tokays will hardly ever let themselves be handled), I believe it is a good principle for small lizards.
Small lizards have some distinct advantages from the keeper's point of view. Firstly and most obviously, they do not require as much space as their larger brethren. For example, a tank or vivarium 30" by 12" will comfortably hold three Leopard Geckos, while a cage of dimensions 18" by 12" by 12" will hold a number of Lygodactylus geckos. An arboreal cage 24-30" high and 12" by 12" in floor space will make a good home for a pair of Gekko lizards (eg Tokays or White-Lineds), day geckos (Phelsuma) or a colony of Anolis lizards. Apart from the lesser energy required to heat and clean a smaller terrarium, Philippe de Vosjoli has also noted that many of the small lizards leave fairly small faeces that dry quickly, which means the cage requires cleaning less often than those occupied by larger reptiles.
Perhaps the most interesting aspect of keeping small lizards, as deVosjoli has also observed, is that some species will live harmoniously in a colony-type arrangement, provided that there is no overcrowding and that hiding places and visual barriers are provided to reduce the possibility of males fighting. This in turn gives rise to a wider range of natural behaviours (often including mating).
There are two factors, possibly disadvantageous, to be considered in the keeping of small lizards. The first is the provision of the correct-sized food. Lizards such as Leopard Geckos or Mabuya skinks will usually take the normal sizes of cricket that can be obtained from your local pet shop, but very small lizards usually require pinheads and possibly fruit flies as a variation in their diet. These smaller and less sought-after food items are often harder to obtain locally, and you may have to purchase them via mail order. The other factor is that preventing escapes is absolutely critical with small lizards (and particularly the very small ones) since once out of the cage they can be extremely hard to find or retrieve, and their smallness makes them liable to dehydrate more quickly. I recommend the use of well-fitting cage locks.
Medium-sized lizards here are considered as those over a foot (12"/30cm) in length but under 36" in total snout-tail length. This category includes such popular species as Bearded Dragons (Pogona sp), Blue-Tongue and Monkey Skinks (Tiliqua and Corucia sp.), Plated Lizards (Gerrhosaurus sp.), water dragons (Physignathus sp.) and the larger European lacertids (Lacerta sp.), plus less commonly-kept but often sought lizards such as the giant New Caledonian geckos (Rhacodactylus sp.), dwarf monitors (Varanus sp.) and various members of the Agamidae. The savannah monitor, Varanus exanthematicus, just squeaks into this category.
Again, it is a generalisation, but one thing many of the medium-sized lizards have in common is that they do adapt to human ownership and will tolerate handling, some actually becoming very tame (bearded dragons and plated lizards immediately spring to mind). Their larger size also means that in some cases they can be allowed out of their terraria for a period (obviously depending on circumstances and environment). In that sense one can talk more of a "pet-owner" relationship. Much depends also on the species, since some do not tame down much at all: make sure you know as much as possible about the species before you acquire it.
The most obvious thing to be weighed against having a larger and tamer lizard is of course the space required to properly keep one. In my own experience I have found that a minimum of 48" by 18" is required for two adults (male and female). Such a cage would also have to be quite tall in the case of many of the agamids, for example, or even longer in the case of savannah monitors. I have found glass to be extremely heavy when used in the construction of such sizes, so I recommend the use of other materials (provided they are safe for the animals) for these cages. Also, the larger size and weight of the lizards makes naturalistic displays (such as planting real plants in the cage) less practical, since after a while any living flora will usually be crushed or eaten. Branches and rocks, however, are both useful and attractive if laid out with thought. Larger lizards also leave larger faeces, as well as sometimes scattering their food. Spot cleaning is a good idea (cleaning out individual stools as soon as they have dried), and I have reverted to using newspaper for many of my medium-sized lizards since it is easily changed and absorbs the mess to a degree.
Lest this sound a bit negative against the medium-sized species, I can cautiously recommend some of them as "pets" (in a more limited sense than, say, a cat or dog), and many do still display interesting behaviour in captivity. Many also live longer than the smaller species. This raises an important reminder: reptiles and amphibians generally have a greater longevity than mammals and birds of the same size. Remember that in purchasing an animal you are making a lifetime commitment to it, which in some cases may be 10, 20 or more years.
This final category includes the true giants: most monitor species (Varanus), tegus and of course the Green Iguana and its close relatives. Lizards in this category are over 36" long and usually at least 48" (tegus) or even 72" (the largest male green iguanas). A few monitor species grow even larger than this.
These are all truly magnificent creatures, which is paradoxically one reason why few people should try to keep them. Put simply, the proper care and maintenance of most of these lizards is beyond the means of most private keepers. Questions of temperament aside (and this can be a real problem with some large lizards), their requirements for space means adapting at least an entire wall to a suitable terrarium for them, if not an entire room. Given not just the length necessary but also the width and height to satisfactorily house a large monitor, and it becomes clear why the reptile house at the local zoo is so large. If you live in a suitable climate (the southern USA or many parts of Australia spring to mind) then you may be able to provide accommodation outside, which in some cases is actually a better idea since the lizards receive natural sunlight and fresh air, but security then becomes even more important, not only to prevent the animals from escaping but also to protect them against other creatures including man.
Tegus and green iguanas merit a special mention here. Both are quite intelligent and do have the capacity to learn and to adapt to their environment. Many seasoned iguana owners allow their iguanas some or much time outside of the cage, often putting up special shelves on the wall, for example, for them to bask on. Similarly, some tegu keepers report that their pet can to a certain degree have the run of the house, becoming almost dog-like. (Such behaviour has also been reported by Robert Sprackland of the Water Monitor, Varanus salvatori). Provided that proper security measures are observed (including the elimination of the danger of objects being knocked over and especially avoiding any risk of fire), this "free-ranging" behaviour can be the most rewarding thing about keeping a large lizard. However, while the danger of salmella has been grossly exaggerated by certain groups (usually as an excuse to seek to ban captive reptiles), it should be taken into consideration, particularly with young children and particularly in the case of the green iguana. Lizards with a doubtful (ie aggressive) temperament also need very careful watching, especially in the presence of children or other pets.
The provision of a cage is at this size of lizard becomes more problematic, since few places stock ready-made terraria of these dimensions. You may be able to have one custom built or ordered, or alternatively if you are handy with woodwork and the like then you may be able to build your own. Some keepers convert human-sized furniture such as old wardrobes. Speaking from experience it should also be noted that in some cases you may have to carry the disassembled parts into the house before putting them together, as failure to be able to bring a large cage through your front door can be annoying and embarrassing!
Finally, it should also be remembered that logistically, large lizards have greater requirements in terms of food eaten (although they will still usually eat less than a similar-sized dog) and of faeces expelled. Monitors in particular defecate somewhat heartily, and if you allow them free roaming at all then you need to be prepared to clean up the carpet. For this reason cage furnishings should also be kept at a minimum, usually a few large branches (especially in the case of iguanas) or a rock for scratching claws on. The use of newspaper as a substrate is heartily recommended.
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