Bosc Monitor / Savannah Monitor Care Guide

In this caresheet I’ll be covering everything you need to know for keeping a Bosc Monitor, also known as the Savannah Monitor, in captivity. This guide will cover Bosc Monitor housing, heating, lighting, water and humidity, diet and I’m also going to discuss the problematic issue with the sources of Bosc Monitors and why they’re one of the animals we rehome so often.

If I miss anything, don’t hesitate to drop us a message on Facebook, email or leave a comment.

Meet the Bosc Monitor / Savannah Monitor

The Bosc Monitor, also known as the Savannah Monitor (Varanus exanthematicus) is a large bodied monitor from Eastern and Northern Africa. An adult Bosc Monitor can exceed five feet in length, although three to four foot is more average. They can weigh up to 2kg and are prone to obesity in captivity, with an almost unrivalled appetite.

Whilst they’re not complicated to care for, we consider these an intermediate reptile species. This is due to their sourcing, size and patience requirements.

Lifespan is often disputed as with previous poor knowledge of reptile husbandry and diet, many Bosc Monitors die young, but with the correct setup, diet and exercise your Bosc Monitor should have no trouble exceeding 10 years, and some individuals have been reported as living up to 20 years.

Housing

An adult bosc monitor will need a very large enclosure, and this requires a bit of planning. The largest mass manufactured enclosure in the UK is 6 x 2 x 2 foot but this is simply not big enough for an adult Bosc Monitor. This leaves you with needing to either have one custom built, or building your own. We would recommend a floor space of at 8 foot by 3 foot for an adult Bosc Monitor.

There is some flexibility in sizes, as some Bosc Monitors might be 3ft and weigh only 1kg, whilst others will be four to five foot and weigh over 2kg. If you rehome an adult Bosc Monitor that is on the smaller side, it’s possible you can use a smaller enclosure. If you are buying a juvenile then you have no idea what their adult size will be and need to be prepared to house them even if they turn out to be on the larger side. A lot of adult Bosc Monitors are rehomed when they turn out to be larger than their owners had hoped.

Heating and Basking

Bosc Monitors need a basking spot of 90 – 100F (32 – 38C), with an ambient on the hot end of 85 – 90F (29 – 32C) and the cool end of 75F (24C).

As your vivarium is going to be very large you may need to experiment with multiple heating options. We can advise you on the exact equipment that would suit if we know the vivarium size, so feel free to message us for personal advice.

Turn off all your lights at night time.

Night time Heating – Night time temperatures can be 70-75F throughout. We recommend using a ceramic on a thermostat. If you use a thermostat that has a day night function, then you can use this ceramic to boost your daytime temperatures as well as provide night time temperatures.

Controlling Heat – You should always control your heat sources with a thermostat. Your heat source plugs into the thermostat and a probe goes into the vivarium. The probe detects the temperature and then automatically adjusts the heating element to the correct heat output. This gives your animal the correct temperature at all times, whilst also saving electricity!

Measuring Heat – You should have a thermometer – either analogue, or digital – in the enclosure as it is possible for thermostats to be faulty and you want to double check that your temperatures are correct. Ideally having one on the hot end and the cold end, or having one with two probes provides you with the best information.

UVB Lighting

For decades people kept Bosc Monitors (And other monitors) in captivity without UVB, but up to date research shows a great deal of benefits of UVB and we believe UVB is essential for Bosc Monitors as an active diurnal lizard.

We recommend a UV Index based on the research by Arcadia, which states 4-6 UVI for Bosc Monitors. This is the in the basking zone, not at the floor of the enclosure, so you need to measure from the bulb to the basking area, which may be a raised rock or slate to help increase temperatures. If the distance is 10-12″ then you want to use a T5 6% UVB or T8 12% UVB. If the distance is 12-18″ then you will want a T5 12%, whilst if the distance is 18-24″ then you will want a T5 15% or comparable.

You can read more about the differences between T8 and T5 lighting in our UVB guide.

Your UVB lighting should be on for 10 – 12 hours a day, which you can set on a timer if you’d like. Always turn off your UVB lighting and your basking bulb at night time.

Water

A large fresh water bowl should be provided at all times, and Bosc Monitors will benefit from a bath several times a month, both for helping shedding and for exercise.

Humidity

An ambient humidity of around 50% – 60% should be fine for Bosc Monitors. You may occasionally want to give the substrate a spray to dampen it slightly and increase the ambient humidity. You may want to provide a humid hide with sphagnum moss if you find your Bosc Monitor is experiencing any shedding problems.

Decor and Substrate

Bosc Monitors love to dig, so giving them a deep substrate of soil, coir, Earthmix, orchid bark or similar helps them stay active. Whilst not natural climbers, they do like to explore and will climb sturdy platforms of branches like large pieces of cork bark. A piece of slate or large basking platform can help absorb heat at the basking spot.

Social Needs and Housing Together

Whilst bosc monitors are not especially territorial, two males will still fight. With the difficulty in sexing Bosc Monitors (see the next section), we would urge you to strongly only get one Bosc Monitor. In addition to this, they are highly keen feeders and will fight over food, so would need to be fed separately, which makes it difficult to encourage them to hunt and leads to potential for injuries. The sheer space required to house two together adequately also makes it difficult. Bosc Monitors are completely happy living alone and we would recommend you to house them solo.

Sexing Bosc Monitors

Most monitors are hard to sex, and Bosc Monitors are no exception. The best way of knowing for sure is witnessing a male externalizing his hemipenes, which look like a large floret of cauliflower coming from the vent, and often surprises first time Bosc Monitor owners! A dominant male may pop them out and drag them on the ground, presumably as some sort of dominance or territorial marking. Males will also have a larger bulge at the base of the tail where they are storing these hemipenes when not in use.

There are minor physical differences but these are hard to be definitive with, and most obvious in fully mature individuals. Females harge a more narrow face, larger nostrils and larger eyes, with a thinner neck and generally more delicate profile. Males tend to be more colourful as well, but this is certainly no guarantee. Males grow a lot faster than females generally and be a bit weightier, but your female could end up a similar size in the end.

Experienced sellers may be able to “pop” a baby bosc monitor, manually popping out the sex organs to give you a definitive answer. The larger the monitor grows, the more muscle they have and the harder this is to do. This can also cause injury, so should only be done by those experienced and comfortable with the process. Unless breeding, knowing the sex of your Bosc Monitor may not matter anyway.

Diet

Bosc Monitors have a large appetite. In the past a lot of people fed Bosc Monitors solely on rodents or dog food, and it has led to a lot of adult Bosc Monitors being overweight. Overweight lizards are very prone to heart problems and other organ failure, so you should try and keep your Monitor fit and exercised and not give in to his large appetite.

Younger Bosc Monitors will take a wide range of live insects such as crickets, hoppers, dubia roaches, mealworms and more. For adult Bosc Monitors you can still try to encourage them to hunt winged locusts if possible, although some will grow very lazy and wait for food to arrive!

Bosc Monitors will eat defrosted mice, but may also take boiled eggs, and butcher’s offal. We do not recommend feeding dog or cat food.

Juveniles should be fed live food every day, whilst adults will eat livefood a few times a week and some defrost rodents once a week. Exactly how much to feed is very dependent from monitor to monitor and you should simply aim to keep them active and not overweight.

Supplementation

Food should be dusted with a multivitamin D3 supplement once a week and straight calcium on all other days.

Exercise & Handling

A regularly handled Bosc Monitor can be extremely tame, but younger Bosc Monitors can be aggressive due to fear and stress. Most Bosc Monitors are very food orientated and this is something you always need to be aware of. If getting a Bosc Monitor you should be willing to commit some time every day – perhaps 30 minutes or so – to handling and exercise. The best way of handling a Bosc Monitor is simply to allow them out of the vivarium in a safe and secure space to roam, introducing them to your presence and getting them used to you. A lazy adult Bosc Monitor may need some encourage to come out and exercise!

Putting on a kitten harness and walking in the garden in the summer is a great way to stimulate a Bosc Monitor mentally and physically.

When holding a Bosc Monitor pick them up securely under the body, supporting all four limbs and body. Never pick them up by the tail.

Swimming in the bath can be good exercise to help keep Bosc Monitors fit and Bosc generally enjoy a bath, although may be upset by the slippery ceramic, so if you can put something they can grip on in the bottom of the bath they’ll feel more secure. In the heat of summer, I’ve seen people offer a Bosc Monitor a child’s paddling pool with warm water in it!

The Bosc Monitor Problem

Bosc Monitors have been bred in the UK but it is very rare due to the size of the enclosure they need, and particularly the depth of digging and burrowing that should be provided. This is a lot easier in countries where they can be kept outside, but the UK is simply too cold.

Thousands of Bosc Monitors are imported “Captive Farmed” into the UK. This means they are not taken from the wild population, but from farms in climates where the adults will live in an enclosed wild situation. This is excellent for maintaining wild populations and far preferable from a conservation point of view, but it is still problematic as these monitors are often shipped at days or weeks old – sometimes with egg umbilical cords still attached – through a stressful and arduous import procedure. Because some of these were reared in an outside environment, they can also have a host of parasites that you wouldn’t get from captive bred indoor animals, which is often made worse by the close quarters with other lizards and the stressful conditions which intensifies the parasite load. Left untreated this can be fatal. This was a huge problem in the 90s and 00s, although far fewer Bosc Monitors are brought into the country these days as the demand has dropped due to increased husbandry knowledge and responsible selling. It’s a shame that they cannot be easily established in the UK as captive bred.

If buying a wild caught or captive farmed animal we always urge people to ask the seller about how long this animal has been in captivity, and if it is a recent acquisition, if it has had a full worming treatment.

The other problem and potentially the larger one, is that Bosc Monitors are often purchased by people without the true understanding of the size of enclosure and the amount of food an adult Bosc Monitor will need. They may also not realize the work required to keep them tame. Bosc Monitors are still often rescued and rehomed. They can have severe health and behavioral problems. Luckily I do believe that more and more shops, perhaps even the majority, are now selling responsibly and trying to keep customers fully aware of a Bosc Monitors needs. By reading this far in this guide, you’ve already taken responsibility by trying to understand their care needs, so this may well not apply to you.

It’s incredibly important that if you’re purchasing a Bosc Monitor you are fully equipped for their entire life, or you could consider offering a home to a rehome or rescue. A Bosc Monitor can make a fantastic pet – but it’s a large commitment. At the time of writing, I’ve been trying to find a home for a rescue Bosc Monitor for over 5 months. In that time we’ve had enquiry after enquiry, but each new home falls through as people realize the enclosure involved.

I really hope that this Bosc Monitor / Savannah Monitor Care Guide has covered everything you want to know. If you have any further questions please drop us a message on Facebook or an email. Thank you!