The Monitor Lizards (Family Varanidae) – Family Overview and Species Accounts, Part II

Hello Dave, Frank Indiviglio here.

Thanks for your comments. Glad you enjoy the articles. It’s my pleasure to respond…keeps me on my toes and hopefully helps others who read your comments and my responses.

Savannah monitors are somewhat problematical…they are very appealing when young, but require a real time and space commitment. Not all are easily tamed, and if not given suitable space as adults, they often become quite stressed and aggressive.

A 20 gallon aquarium is barely suitable for a hatchling, and would not be so for more than a few months. An adult will need a cage of at least 6-8 feet square and with a good deal of height…something along the lines of a modified bird aviary. It’s very difficult to provide a thermal gradient for large lizards in small cages, even if activity levels were not an issue (heating a basking site to the required 100 F or so will result in overheating the entire space in a small cage).

There is some evidence that certain heliothermic (basking) lizards and turtles can get by without UVB, but only if dietary factors are perfect; its also dangerous to generalize from research done on only a few species (please see my article on Chameleon Basking Behavior for further details). The tried and proven method for savannah monitors is to provide a high quality source of UVB and UVA radiation.

Bottom line is that these lizards are extremely interesting and relatively handle able under some circumstances, but their purchase requires a good deal of thought. Zoos and rescue centers are overloaded with unwanted monitors, and rarely accept donations.

Please keep me posted,

Best regards, Frank Indiviglio.

Hello Dave, Frank Indiviglio here.

Thanks for your feedback.

Sounds like a good idea. If you’re set on a monitor, you might want to consider a Storr’s monitor (Varanus storri) or another small species. A 40 breeder would be perfect for one, or even a compatible pair. Their behavior, intelligence level, responsiveness etc. is exactly the same as the larger species, with the added benefit that you can easily supply them with all they need in captivity. This allows you to see their entire range of behaviors, and perhaps to breed them; larger species are almost impossible to accommodate properly (living, foraging etc. in a somewhat natural manner, as opposed to merely surviving captivity) in most private collections.

Best regards, Frank Indiviglio.

Hello Dave, Frank Indiviglio here.

Thanks for your comment. Storr’s appear from time to time as captive bred youngsters, but not regularly; seem to be more popular with European herptoculturists.

Timor and related arboreal monitors have a lot to recommend them. They only reach 3-4 feet but are very active and need lots of room, especially vertical space – an outdoor aviary or custom indoor cage of 4-5 feet in height would be ideal. They and the blue tree monitors (V. macraei) and mangrove monitors that I’ve worked with have always utilized every inch of their environments, moving among different basking sites, foraging along the floor, etc.

The smaller black and green tree monitors (V. prasinus/beccarii) are easier to provide for if you’re considering in arboreal monitors, and just as interesting.

Good luck and best regards, Frank Indiviglio.

Hello Steven, Frank Indiviglio here.

Thanks for your interest in our blog.

US breeders sometimes offer them on Kingsnake.com, but infrequently; I would check this site for a UK based breeder, as shipping would not be advisable. You can find a list of UK Herp Societies here…members may be able to direct you to a local breeder.

Good luck and please keep me posted.

Best regards, Frank Indiviglio.

Hello, Frank Indiviglio here.

Thanks for your interest in our blog. In recent years, we have discovered that all monitors (Family Varanidae), including the savannah, likely do produce venom. Usually, a bite causes only pain and swelling, and no human fatalities have been reported; the venom seems designed to kill or slow-down the monitor’s prey. There is always a chance, however, that certain people could be sensitive or allergic, in the same manner as some people can be killed by a bee sting.

Best regards, Frank Indiviglio.

Hello Michael, Frank Indiviglio here.

Thanks for your interest in our blog. Great choice…if you provide a large enough cage, you’ll be able to see a great many natural behaviors, and even possibly breed them in time.

Timors are largely arboreal, so provide as much height as possible…a custom/home-made cage, in legs if possible, is best. Stock it with plenty of stout branches and large cork bark rolls; some individuals remain shy for long periods of time. Provide many hiding spots – the more security the lizard has, the more likely it will calm down and show itself.

Hide spots should be attached to the upper branches in your cage – cork bark rolls or homemade “birdhouse” style retreats work well. Pine chips can be used on the floor – spray the cage 1-2x daily; they are native to humid habitats. Be sure to provide UVB and a basking spot of 90-95F and a water bowl large enough for soaking.

Timors likely have a varied diet in the wild, given their size. Rodents can form the bulk of the diet; I prefer to alternate between pink/fuzzy mice and adult mice, as they likely do not catch adult (furred) rodents exclusively in the wild. Also give them roaches, super-mealworms, crickets, locusts and silkworms; (those I’ve kept loved wild caught grasshoppers as well), chicks and minnows. Hard-boiled quail or chicken eggs are also relished.

Enjoy and please let me know if you need \more info.

Best regards and please keep me posted on your progress, Frank Indiviglio.

Hello Michael, Frank Indiviglio here.

Thanks for the feedback. Providing UVB is the safest route to go. In most cases, monitors cannot fully utilize the Vitamin D3 in powdered supplements – they need to manufacture it in their skin (by basking in UVB of the proper wavelength). Without D3, they cannot metabolize dietary calcium. Basking lizards will also naturally adjust their exposure to UVB to meet their needs, which is not possible when dietary D3 alone is used. There is some evidence that certain heliothermic lizards (species that bask to produce D3) can use dietary vitamin D3 (please see this article re my experience with this), but providing UVB is the best way to go, especially for animals still growing. Most monitors grow quickly and suffer Met Bone Disease if denied UVB (big problem with zoo-bred Komodos). The ZooMed 10.0 is the strongest florescent – the basking site should be within 6-12 inches of the bulb. For longer distances, use a mercury vapor bulb (this provides heat as well, and some UVA). UVA is likely of value as well, but not as critical as UVB.

Providing a large water bowl for soaking is the best way to loosen skin; most will use this if available. You can try a applying a shedding aid and manually removing the skin, but hold off on this if possible as it may stress the animal. Long term unshed skin can lead to bacterial infection, but monitors typically shed over time and are not as prone to problems as are snakes.

Enjoy and please keep me posted,

Best regards, Frank Indiviglio.

Hello Michael, Frank Indiviglio here.

Thanks so much for the kind words, happy to be of assistance. Yes, the net can be a great resource, but it has it’s downsides as well. Concerning subjects that are new to me, I tend to be very careful.

The lizard will not get the benefit of UVB unless it actually basks, but it may be basking when alone. It may not, however, feel the need to warm up (having UVB paired with the hot spot is the best option, as they are drawn to the heat) if it remains very warm within the shelter. This can be tricky, because if you move the shelter to a cooler area, the lizard may still remain in it too long, and will be too cool. I suggest leaving as is, and situating the UVB source near the heat lamp. Vitamin D/Calcium deficiencies are long term processes, so you have time to experiment.

Providing shelter and security is really the only way to get them comfortable enough to move about and be seen. Unlike some monitor species, handling rarely works with Timors and similar (generally small, arboreal) monitors. They are very perceptive – noises, and perhaps scents, even when the animal is within the shelter, can prevent them from moving about.

If it takes crickets, you might try leaving some at large in the cage it is cricket-proof..he may start to forage in time. Allowing super mealworms to burrow into the substrate is another trick – the scent may get him moving. A timed mister can help also to get him moving as well. You can also keep him a bit hungry, then rub a mouse on branches and hide it under something…sometimes do not leave it in cage at all. Eventually he may begin searching for food by day. Some go crazy for hard boiled eggs and chicks, but be careful he does not become “fixated” on these items (not as common in monitors as in some snakes).

His behavior should change in time, but it’s very individual…I’ve had black, green and blue-spotted monitors that remained shy for years, even in quiet off-exhibit locations. I mainly observed them from a distance, using some of the tricks above.

Did you see this new info on Rosenberg’s Monitors?

Enjoy and please keep me posted.

Best regards, Frank Indiviglio.

Hello Michael, Frank Indiviglio here.

Thanks, my pleasure…please write in anytime.

I don’t personally know any private folks breeding lace monitors. Just in passing, I see them offered more by breeders in Australia than elsewhere. Make sure you have an empty room available if you plan on raising one – they are huge and active!

Please let me know if you need any further information. Good luck, enjoy and please keep me posted.

Best regards, Frank Indiviglio.

Hello Ashish, Frank Indiviglio here.

Thanks for your interest in our blog. It’s difficult to compare intelligence levels among reptiles, because their different life styles require each to develop unique survival strategies. However, most herpetologists do believe that monitors are among the most highly intelligent of all. I have noticed that they respond very quickly to changes in their environment, and seem to “plan” ahead…please see this article for more info. There are field reports of monitors running away from fleeing prey (rabbits) in order to circle around unseen and wait by the rabbit’s burrow in ambush! This seems to go beyond instinct.

Please let me know if you need any further information. Good luck, enjoy and please keep me posted.

Best regards, Frank Indiviglio.

Hello Ashish, Frank Indiviglio here.

Thanks for your post…many people wonder about this. Yes, Komodo Dragons are monitors. All monitor lizards are placed in the Family Varanidae. Please check here for a list of all 73 known species and information on where each lives. The Komodo Dragon will be listed as Varanus komodoensis.

Please let me know if you need any further information. Good luck, enjoy and please keep me posted.

Best regards, Frank Indiviglio.

Hello Ashish, Frank Indiviglio here.

Thanks for the feedback. I’ve spent most of my life as a biologist/herpetologist for the Bronx Zoo, where I was lucky enough to be involved with everything from animal care to field research. I currently a writer (books, this blog for ThatpetPlace) and consult for several zoos and museums. You can see a more complete bio here.

You might enjoy this article and the others linked there.

Good luck, enjoy and please keep me posted.

Best regards, Frank Indiviglio.

Hello Ashish, Frank Indiviglio here.

Thanks for the kind words; I look forward to your future questions, comments or observations.

Please let me know if you need any further information. Good luck, enjoy and please keep me posted.

Best regards, Frank Indiviglio.

Hello Ashish, Frank Indiviglio here.

Nice to hear from you again. Recently it has been discovered that certain monitors (i.e. the Komodo Dragon and Lace Monitor) do produce venom. All venom (snake, lizard) is derived from modified salivary glands, and is in a sense a “type” of saliva, but it is a unique compound, different from true saliva. Research is ongoing – other monitor species will likely be found to produce venom as well. Other lizard families are also surprising us – fro example, the Bearded Dragon has primitive venom glands, and produces a mild toxin!

Please see paragraph two of this article for a bit more info.

Please let me know if you need any further information. Good luck, enjoy and please keep me posted.

Best regards, Frank Indiviglio.

Hello Ashish, Frank Indiviglio here.

Nice to hear from you again. So far, studies have shown that monitor venom affects blood pressure and the blood’s clotting ability. I’m not aware of any articles establishing a direct effect on skin. Monitor venom seems to have evolved from a common source with snake venom (please see this article for further info on venom evolution). Snake venom dripped onto the skin has no effect (although spitting cobra venom in the eyes is dangerous). I’ve had venom from various snakes come in contact with my skin while working with veterinarians at the Bronx Zoo, and have had no reaction.

Of course, we may learn more in time. Also, venom, saliva and other fluids may contain bacteria that can cause skin reactions or severe internal infections. This is why any cut, however small, or any fluid from an animal that contacts the skin, must be treated as a serious concern and cared for properly.

Please let me know if you need any further information. Good luck, enjoy and please keep me posted.

Best regards, Frank Indiviglio.

Hello, Frank Indiviglio here.

Thanks for the feedback; Komodo Dragon bites always cause serious reactions (in addition to the trauma); not much known on the effects of the venom of other species on humans. As with snakes, some venoms may be very specific, and affect only certain prey species, but it’s never a good idea to treat any bite lightly.

Please let me know if you need any further information. Good luck, enjoy and please keep me posted.

Best regards, Frank Indiviglio.