Monitor Lizard Care Guide
Facts and Figures for the Monitor Lizard
Monitor lizards are indigenous to Africa, Asia, Australia, and Indonesia, living in habitats as varied as deserts, forests, and savannahs. Some monitors are primarily terrestrial, while others are arboreal. Most monitors are good climbers regardless of where they are found. Touted as the most intelligent reptile on earth, they make fascinating pets, if one can provide enough space for them. Monitors can vary greatly in size. Smaller species can be less than a foot long, but many larger ones can grow to be six feet or more in length.
Monitor Lizards are predators & scavengers
They will eat insects, birds, rodents, fish, frogs, other reptiles, eggs, and any other animal small enough for them to catch. They are also opportunistic scavengers and will eat carrion when they find it.
Some species are gentle and sociable, others extremely aggressive. For instance, the Komodo dragon is the largest living lizard and member of the monitor lizard family. It can be over nine feet long and weigh over 200 pounds. Their natural prey, a small indigenous deer, is being decimated by poaching, causing this canny predator to seek other prey, namely, people. One park ranger sitting quietly at his desk in a park hut was attacked by a hungry dragon that climbed the steps to the hut and grabbed his leg. Plainly, this animal strategized the best approach to acquiring an alternative prey item!
Not all monitors possess such ferocious tendencies. In fact, as a family, they present the keeper with a very wide range of options. Some species are gentle and easy to acquire such as the savannah monitor (selling for about $25 for a baby), while others can be quite expensive, going for as much as $700 for a juvenile. Some species are slow and docile, while species such as the Nile monitor are notoriously aggressive. And some are lightweight, arboreal insectivores, such as the black tree monitor, while others are stocky, ground-dwelling carnivores, like the savannah monitor.
Spend Time Researching This Challenging Reptile before Buying
For the potential keeper, the family Varanidae provides a wide variety of sizes, temperaments and husbandry considerations. They are, therefore, a diverse group of large, often powerful lizards, none of which should be purchased on a whim. For these reasons, one of the most important parts of choosing a monitor lizard as a pet, in addition to budgetary considerations, is to thoroughly research the species you are most interested in to get an idea of any one species’ pet potential and husbandry needs.
For instance, the black tree monitor is a very manageable small size, seldom exceeding 45 inches in length (including tail). However, black tree monitors tend toward a nervous temperament. Although gentle and regular handling can help to partially tame these lizards, black tree monitors make better observational specimens than “petting” pets. These animal tend to be on pricey end of things as well, selling for between $500 and $700 from a reputable breeder. Contrast this species with other more social if larger, species such as the savannah monitor, before making a final decision.
Monitor Lizard Habitat Design
More Room, the Better
As is true with all monitor species, the more room you can provide your pet, the better. Large, screen-walled habitats with wooden framing and screen roofs (to accommodate overhead lighting apparatus) are the most cost-effective way to house your monitor. Arboreal species such as the black tree monitor will require a vertical arrangement. And terrestrial species require plenty of horizontal space.
Pro's and Con's of Screen Enclosures
Although practical in many ways, screened enclosures have the disadvantage of making temperature and relative humidity regulation challenging. The horizontal habitat, with glass sides, needed for a juvenile savannah monitor is much less demanding to maintain in terms of light, temperature and humidity, but this animal will outgrow it’s enclosure within 18-20 months, so be warned. An adult savannah monitor will eventually require a custom built enclosure that is at least 8 feet long.
How Much Space does a Lizard Monitor Need?
- 30 gallon tank for small lizard monitors
- 55 gallon tank for 18" in length
- custom made enclosures for larger monitors
General space guidelines for young savannah’s and other ground dwelling monitors are nothing smaller than a 30-gallon horizontal tank for a small individual, a 55 gallon for a larger specimen of 18 inches or so, and a larger, custom-made enclosure for older juveniles and adult specimens. Additionally, allowing this animal to roam freely in a safe contained environment, such as an inescapable pen or closed-off room, is an excellent practice for the long-term happiness and welfare of your pet.
Height is a consideration even for a ground dwelling monitor. Even the squat and heavy bodied savannah enjoys a bit of climbing now and then. And furniture can add interest to the enclosure as well as providing added opportunity of a variety of body movements. A black tree monitor will need lots of stable climbing branches (affixed to the enclosure walls by screws or bolted into a stable wooden base) while the savannah monitor will need only a couple.
Lizard Monitor Substrate
The best substrate for a savannah monitor is a mixture of plain potting soil and cypress bark, mixed one part bark to two parts soil. Eco Earth, made from coconut fiber, also makes suitable bedding for virtually all species of monitor lizard.
For adult savannah monitors (Savy’s in the trade lingo), this substrate needs to be very deep, at least 6 inches. For juvenile Savy’s and arboreal species, the substrate materials can be the same, and the depth only 2-3 inches. Small Savy’s may have live plants anchored in their terrariums; larger monitors will likely trample and utterly destroy most plants. Large succulents such as aloe vera may be the only choice for adults of this species for keepers who insist on including plants. A little sand should be mixed into the organic matter and the substrate for adult savannah lizards needs to be kept slightly moist at all times to enable stable burrow construction by a savannah monitor.
For all species of monitors, lighting should consist of at least eight hours daily of full-spectrum ultraviolet lighting. Many hobbyists build movable habitats and wheel them outside on sunny days so that the monitor may benefit from natural sunlight.
Outdoor Habitat for Sun-Bathing
Another popular option is to have a second habitat outside that is very securely built, where you can place your lizard during the day. Make sure it has a shady retreat, so that the monitor may escape the heat of the sun if necessary. As with any species of reptile, overexposure to direct sun without the option of shade can cause your pet to overheat, resulting in death fairly quickly. Just like it is not OK to leave a dog locked in a car in a parking lot on a hot day (or a child for that matter), be mindful of your pet’s comfort when placing it outdoors. If you feel you don’t have the time to monitor your monitor properly during a sun session, then just skip it till you do.
Temperature and Humidity
Maintain daily ambient temperatures within the enclosure in the mid-80s Fahrenheit, with a basking spot reaching into the high 90s to low 100s for both arboreal and terrestrial monitors. Nightly ambient temperature drops of 10 degrees or so will help maintain a normal sleeping regime for these diurnal creatures. But it's critical that the owners never allow these temperatures to fall below 80 degrees, ever.
Savy’s need a scorching 105 to 110 degrees F under their basking light to emulate the Sudanese habitats they prefer. This is a good ambient air temperature at the warm end of their enclosure, and their basking rocks can achieve a surface (not air) temperature of 130 F. When thoroughly warmed, the monitor will leave basking area for a cooler location, so the ambient temperature throughout the enclosure should not exceed 110 at any time. For comfort and safety, the habitat needs a cooler end of around 85 degrees furnished with a humid hide or two.
The humidity at this end should be about 60-70% and this can be achieved by providing a heavy, wide and shallow water bowl. These lizards do drink quite a bit of water, and like most monitors, they prefer to defecate in their water rather than on dry land, so the water needs to be changed daily and the bowl sterilized either with bleach or on the hot cycle of a dishwasher every other day.
This tendency makes this species a little challenging for keepers with busy schedules, and so needs to be taken into consideration when pondering pet lizard species and their husbandry needs. These lizards will soak in their water bowl periodically, especially when molting. If the water bowl is not large enough to easily allow this, then keepers of savannah monitors should put them into a bathing tub once a week. That may seem odd for a desert species, but they will indeed thank you for it. This treatment is not necessary for an arboreal monitor, but misting twice a day is.
For black tree monitors, a relative constant humidity of 60 percent or higher at all times is also required. In the wild, this species seldom descends to the ground, so offer them water by securing one or more small, shallow dishes amidst their climbing structures. Misting the habitat with a spray bottle of dechlorinated water multiple times daily is highly recommended. Again, dishes need to be refilled and cleaned daily.
Lizard Monitor's Diet and Feeding Schedule
Feeding is a particularly interesting aspect of keeping monitors; these hardy carnivores are eating machines! Virtually anything that moves is on the menu, so you will have to be diligent in ensuring that your pet doesn’t overeat. In fact, obesity related disorders such as fatty liver, are leading causes of death among monitors. Be aware that diets that are consistently too fatty or too packed with meat proteins are problematic.
In the wild, the staple diet of many smaller monitor species is insects and other invertebrates. Recent studies have shown that presumed rodent eaters such as savannah monitors, actually consume mostly termites, millepedes, and scorpions. In captivity, these foods may be difficult to procure, but other insect species are readily available, and should be part of every small or juvenile monitor diet. Crickets, mealworms, waxworms, and roaches should be considered items.
Invertebrates fed to your monitor should be gut-loaded prior to offering them to your pet. “Gut loading” means placing the feeder insects on an enriched diet for at least 24 hours prior to being offered to your monitors. This enhances the nutritional value of the insects substantially. A purchased supplement such as those offered by reptile hobby stores is easily available and affordable.
The convenience of a dry gut load diet, purchased from a pet supply house, is undeniable. However, many experienced breeders and keepers have found these products inadequate, so for the really persnickety keeper (and you know you should be) the following formula for gut loading your feeder crickets or roaches is suggested.
- 24 pbw whole wheat flour (not self rising)
- 8 pbw calcium carbonate with vitamin D3
- 4 pbw brewer's yeast (Not baker's yeast).
- 3 pbw soy powder
- 1 pbw paprika (this is to provide beta carotene)
The ‘pbw’ stands for parts by weight, whatever that weight may be. Think of this formula as a table of ratios. For instance, if you begin with 24 tablespoons of whole wheat, you would add 8 tablespoons of calcium carbonate and so forth. So for every unit of whole wheat flour, you would add 1/3 as much of the same unit of calcium powder and so forth.
Vegetables are also important for gut loading as a source of beta-carotene, which is processed by the insects into retinol, a form of vitamin A that savannah monitors can use. Good vegetables are often bright in color and not too high in oxalates and phosphorus. Sometimes the healthiest foods are:
- hibiscus flowers
- acorn squash
- butternut squash
- bell peppers
- green beans
- snap peas
- yellow squash
Because monitor lizards are obligate carnivores, gut loaded insects are their only means of acquiring the nutrients needed for optimal health. In the wild, your pet’s prey items would naturally gut load themselves with a wide variety of vegetable foods, but the pet store variety may be impoverished in this regard. So it is up to the keeper to remedy this. Place your feeder insects onto this feed for 24 hours and then release several into your monitor’s enclosure.
Feeding method can be instrumental in taming shyer or naturally aggressive species. This is one compelling reason to err on the side of abundance in feeding mice. When ‘training your dragon’ it is critical to start with a young juvenile. Their developing brains are more likely to accept the lesson that human touch is not to be feared and human hands are not to be eaten.
If offering pre-killed food by hand in order to train, it is important to keep the enclosure a little on the warm side of the normal range and to make extra efforts to provide your youngling with opportunities for exercise outside of the enclosure whenever possible. And whatever the new keeper does in this regard, they should not attempt it until the new acquisition has been in their care for at least 30 days, well cared for but essentially left alone until they get used to their new habitat.
It is widely accepted to feed only pre-killed rodents to monitors. Live mice and rats can easily injure the animal they are intended to feed, resulting in lacerations, infections, or abbesses. Also, by offering non-living rodents, your monitor's vigorous hunting response will be slightly reduced, thereby lowering the chance of an accidental bite to the keeper’s hand.
When feeding rodents by hand (not literally by hand, but rather with tongs or forceps), it is best to use weaned mice (fuzzies) as soon as the lizard is old enough to swallow prey of that size. Unweaned baby mice (pinkies) are fattening and have almost no calcium benefit for your growing monitor. Given an understanding of just what size of rodent meal your monitor can swallow without choking, it is best to feed rodent prey items that just barely ‘go down the hatch’.
Also, it is important to have a comprehensive knowledge of your particular monitor species natural prey items. It is fine, indeed recommended, to feed a Nile monitor small fish from your local bait and tackle shop. But this would be an inappropriate choice for a savannah monitor as a steady diet and totally inadvisable for a black tree monitor. Using appropriate pre-killed prey items for training purposes twice per week is acceptable as long as the animal has plenty of room for exercise.
For passive feedings, in addition to insects, or for monitors that are too large to be interested in insects any longer, keepers who have been working with monitors for any length of time often formulate their own food staples using what is known as the SDZ diet. Quite a few years ago, keepers and animal nutritionists at the San Diego Zoo were experimenting with non-rodent based diets for their larger monitor species. At the time, they were working intensively with Komodo Dragons, but the diet they derived is now considered acceptable for all monitor species.
While the original formulation is not exactly known, it is widely now accepted that it contained nothing more than raw, ground turkey, eggs, steamed bone meal (as a source of calcium), and multivitamins. One experienced keeper reports having good results with one pound of raw, ground turkey mixes with two raw eggs including the shells. He replaces the steamed bone meal with one heaping tablespoon of a high quality calcium/vitamin supplement designed specifically for reptile use. Mix this well, and feed your lizard whatever it will consume in a few moments. The remaining mixture can be frozen in ice cube trays or larger containers for future feedings. This keeper uses this formulation to supply 70% of his monitors dietary needs.
Cleaning the Enclosure
Because of the size of the enclosures needed, many keepers will find themselves building their own out of plywood and screening. An 8 foot long enclosure with wooden sides is super heavy and hard to clean. It is for this reason that a bioactive substrate is highly recommended for any monitor species over 18 inches long.
A bioactive substrate will contain the mix of orchid bark or potting soil and sand as mentioned above, plus dried oak leaves scattered on top and a healthy dose of detritivores. For small monitors, the clean-up crew (trash eating insects) can consist of small isopods and springtails, but when you pet gets bigger and poopier, the enclosure will need to be supplied (and resupplied occasionally) with millipedes and centipedes.
The substrate needs to be kept slightly damp for the welfare of the detritivores, but then it needs that any for the comfort and humidity of the monitor. If a bioactive system is selected for an arboreal species, then the substrate depth will need to increased to 5-6 inches. With this system, the enclosure may need to be cleaned only once every 4-5 year.
The water bowls and furniture are an exception to the no cleaning rule. Furniture that is elevated, such as branches and basking areas, will be need to be spot cleaned and occasionally sanitized (twice a year or so as needed). The water bowls will need constant maintenance due to the high temperatures required by monitor lizards of various species and their tendency to poop in their bowls.
This makes a neglected bowl the perfect Petri dish for all kinds of nasty germs, so this action must be at the top of the keeper’s daily chore list, along with misting. Although live plants are often considered to be an attractive and integral part of most bioactive systems, the weight and activity level of these pets makes keeping plants alive in enclosures that contain adults virtually impossible. Instead, keep plenty of leaves on the substrate surface to compensate for lack of plant roots so that the detritivores should be able to find enough small undisturbed pockets of soil to be able to reproduce in them and keep your clean-up crew population at stable numbers.