Bosc Monitor Care Sheet (Varanus exanthematicus)

Bosc monitors are one of the best larger pet lizards that can be kept in captivity. This care sheet reveals how to look after Bosc monitors - a perfect read for all reptile enthusiasts, or those looking for a pet lizard. Bosc monitors are one of the more popular large lizard species kept in captivity. Hailing from Eastern and Northern Africa, the bosc monitor is capable of growing up to five feet (150cm) in length, though in reality most specimens top out at a more modest three to four feet in length (90-120cm).

While these certainly aren’t the biggest lizards available to reptile keepers, they’re certainly a far larger and more impressive species than the more commonly-kept bearded dragon or leopard gecko.

Together with their impressive dimensions, be aware that their teeth and claws are also in proportion of their body. A scratch or a bite from a bosc monitor is therefore likely to be much more uncomfortable than from a Green Anole! That said, a properly-tamed bosc monitor can become silly tame, posing no major risk for their owner.

Their potential size, combined with a fearsome arsenal of tooth and claw – not to mention a powerful tail – therefore mean that the bosc monitor is generally not a good pet lizard for beginners.

For reptile keepers with some experience, however, looking to upgrade to something a little bit different to the usual species seen in reptile stores, the bosc monitor can make an ideal introduction into the larger and more impressive lizards.

In this bosc monitor care sheet we’ll discuss everything you need to know in order to safely house, feed and care for your first pet bosc monitor…

Wild Habitat

Hailing from the arid regions of Northern and Eastern Africa, bosc monitors may be found across a wide range, including Ghana, Senegal and Ethiopia.

They are typically ground-dwelling lizards, though may occasionally climb when the desire arises. Far more commonly, bosc monitors use their sharp, elongated claws to dig. In doing so they may create a hole in which to hide, or may unearth potential prey.

Bosc monitors are carnivorous lizards, naturally hunting throughout the day where they feed on whatever live prey they can capture. With their forked tongues, they prowl the wild areas of Africa, looking almost like small komodo dragons, tasting the air for any tasty morsels. In the wild this is likely to consist primarily of a wide range of life invertebrates, supplemented with the occasional rodent or eggs from ground-nesting birds.

When it comes to bosc monitor care the best solution is to try and mimic this natural lifestyle as far as is possible in captivity. This means that a large cage will be required to enable these active lizards to explore and hunt.

A very hot basking area is also recommended, to help mimic the effects of the sun’s rays warming the earth. A drier environment is also preferable to more humid atmospheres, which can lead to health problems in bosc monitors.

Lastly, giving your monitor the opportunity to dig around in their substrate, and even to take a nice long bath, will also help to add interest and to foster more natural behaviour in their captive environment.  

Housing Bosc Monitors

Many people are taken in by how cute (and relatively inexpensive) baby bosc monitors are. They can often be purchased for similar prices to bearded dragons, and being less than a foot in length the chunky babies can be very appealing indeed. It is important, however, to appreciate just what you’re getting yourself into before buying a baby bosc monitor.

While young bosc monitors will be happy in a traditional wooden vivarium or large Exo Terra tank, adult specimens will require a far more roomy enclosure. Youngsters can be successfully housed in a tank measuring roughly three feet (90cm) in length, and eighteen inches (45cm) in depth.

Appreciate, however, that baby monitors can double in size in a matter of months when well cared-for, so it is often to start off with a larger cage of 120cm or more. This means that such a cage can be used for a longer period of time before rehousing is necessary.

Such a plan helps to save you money rather than needing to buy a new cage every few months. In the meantime, of course, your baby monitor will be able to get plenty of exercise, exploring their oversized cage until they grow into it.

Adult bosc monitors require considerably larger enclosures, which can be difficult to source from standard reptile stores. A cage of some six feet (180cm) in length, with a height and depth of three feet (90cm) is recommended as a minimum for adults. Due to the excessive size it may be necessary to build your own vivarium as your monitor reaches maturity (and process that can take just 2-3 years), or to order an over-sized vivarium from a specialist tank builder.

As bosc monitors like a hot and dry environment wooden vivariums are often the best option. These successfully hold in the heat, while making it easy to attach the various electrical appliances you’ll need. The wood also won’t rot in the otherwise dry environment. Cheap to buy “off the shelf” or to build yourself, this is often the most practical and cost-effective solution.

Heating & Temperatures

To mimic their wild environment, bosc monitors need a hot enclosure. As with other reptiles, it is recommended that one end be heated while the other end of the cage is allowed to remain slightly cooler. Under such conditions your monitor will be able to choose their preferred area; warming up under their heat lamp and then going off to explore the cooler areas of their cage once they have reached their optimum temperature.

A recommended temperature at the hot end is some 28-32’C, though this can drop during the night. This should be monitored continually with a reptile thermometer such as a digital thermometer or heat gun.

There are a number of ways to provide this level of heat. The first of these, and arguably the most popular solution, is to use a heat lamp. Alternatively ceramic heaters may be used. Ceramics don’t provide light; just heat, so some bosc monitor owners find them more practical as they can be run safely during the “night” without upsetting your bosc monitor’s natural circadian rythmns.

Note that both heat lamps and ceramic heaters can get very hot indeed. Not only do such heaters risk overheating the cage, but lizards can receive hefty burns if they’re unlucky enough to come into direct contact with the heating element. As a result, a number of precautions are essential for the health of your pet…

Firstly, any heating element should be safely protected with a bulb cover to eliminate any chance of your monitor coming into contact with it. Additionally, such powerful heaters should only ever be used with a thermostat.

There are a range of thermostats designed specially for reptiles, and they help to keep temperatures within acceptable levels. On colder days, the thermostat can gently increase the power of the bulb to maintain a suitable environment, while on hotter days it will be automatically turned down to prevent overheating.

Depending on how well-insulated your chosen bosc monitor cage is, and it’s overall size, it may be necessary to add supplemental “background” warmth to take the edge off the cooler end. This can be easily, cheaply and safely achieved through the use of one or more heat mats.

The best guide to heating your bosc monitor cage will be your lizard itself. Pay attention to his or her behaviour to see if changes are necessary. A monitor that only rarely ventures away from the basking spot could likely do with the temperature increasing further. In contrast, of course, a monitor that rarely goes anywhere near their hotspot, but instead lurks at the cold end may be finding their enclosure too hot.

By modifying the temperature of your bosc monitor’s cage in response to their behaviour you should quickly be able to find the optimum conditions for your pet.

Ultraviolet Lighting

Lighting your bosc monitor cage is a point of great contention. Veterinarians and reptile keepers alike are aware that some lizards – such as green iguanas – positively must have artificial lighting. Without the provision of UV light, such lizards are unable to effectively metabolize calcium, which can lead to weak bones, swollen joints, paralysis (particularly of the rear end) and sometimes even death.

It has been claimed by some authorities, however, that bosc monitor’s do not require UV light and can live perfectly happy and healthy lives without. Some keepers have even successfully bred boscs without the provision of artificial lighting.

That said, it does seem like an unnecessary risk when the reptile community is so divided. As a result, I recommend the use of a suitable UV bulb, placed as close to your lizard’s basking spot as possible. Ideally, the distance between lizard and tube should be no more than 30-45cm or so.

To maximize the volume of ultraviolet light available to your monitor use a reflector behind the bulb. Also be aware that most bulbs require changing every six months or so. Even if the visible light appears bright, the UV portion (invisible to our eyes) drops away over a period of months. If in doubt, a handheld UV monitor can be used to check the output of your chosen bulb.

Also, in cases where you opt to provide a UV light, your monitor should have ample opportunities to escape the glare. This means providing light in just one area of the enclosure, while also providing hides and artificial plants, where your bosc monitor can retire if desirable.

Water & Humidity

Bosc monitors may come from arid areas of Africa, but it is still considered a good idea to provide fresh water at all times. This should be provided in a heavy ceramic bowl, to prevent these powerful lizards from tipping over their water.

Like many other monitor lizards, it seems that bosc monitors often appreciate a nice soak in their water bowl. Selecting a bowl that will accommodate your bosc monitor safely can therefore be a wise idea. Note that monitors have an unfortunate habit of defecating in their water, so you’ll want to scrub the bowl and change the water regularly to keep it hygienic.

Normal household humidities are perfectly acceptable for bosc monitors, with no additional spraying generally being required.

Tank Decor

The first consideration when setting up your bosc monitor cage is the substrate which goes on the floor, and here there is much disagreement. Some keepers use orchid bark or beech chippings, though it is generally accepted that potting soil may be the best solution. Be certain that the compost you choose does not have any nasty chemicals added to it, such as the artificial fertilizer granules found in some brands.

Mixing this compost with some children’s play sand then creates the perfect environment for digging. In larger vivariums it can be a good idea to offer a healthy depth of substrate, and to pack it well. This enables your bosc monitor to dig naturally in the substrate as they might in the wild.

Bosc monitors are large, powerful lizards capable of digging and climbing. As a result, a beautifully-landscaped vivarium may not stay so for very long. Instead, tank decor elements should be sturdy, and ideally fixed in place with screws or reptile-safe silicone sealant. The use of large branches and pieces of cork bark, combined with artificial plants, can be put to use to create an appealing and varied environment for your monitor.

Lastly, don’t forget to provide your bosc monitor with somewhere suitable to hide away from prying eyes. There are a huge range of potential reptile hides, but the size of an adult monitor means that a very large piece of curved cork bark may be the easiest solution. For youngsters reson caves or curved wooden hides can also work well.  

Feeding Bosc Monitors

Learning how to feed your pet is a critical aspect of bosc monitor care. The reason is that bosc monitors can be prone to laziness and, as a result, may become obese over time. Over feeding your bosc monitor, or providing it with the wrong food can therefore lead to an overweight lizard which will, in all likelihood, shorten it’s lifespan.

Young bosc monitors are best fed every day or two, on a wide and varied selection of livefood, including crickets, locusts, mealworms and even earthworms. All livefood should either be dusted with a suitable mineral supplement, or gut-loaded before feeding. Doing so maximizes the mineral content of the food, helping to keep your monitor in the best of health.

As your lizard grows, so the feeding frequency can drop. Alongside this, the size of prey items provided can increase. Many experienced bosc monitor keepers offer dead mice to their pet roughly twice a week (every three days or so). This rodent prey can be supplemented with further invertebrate prey as desirable.

Bosc monitors are one of the best larger pet lizards that can be kept in captivity. This care sheet reveals how to look after Bosc monitors - a perfect read for all reptile enthusiasts, or those looking for a pet lizard.

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