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Bosc Monitor

Bosc Monitor
Varanus exanthematicus

Bosc Monitors also known as Savannah Monitors, originate from Africa. Large monitor lizards come with challenges; from temperament to housing, equipment and upkeep costs, please take time to read our care guide.

OriginCentral/Southern Africa
Adults SizeUp to 3 foot
LifespanUp to 20 years
Food TypeCarnivorous Insects/Meat

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What does the Bosc Monitor look like?

Bosc Monitors are a stocky monitor species, generally greyish-brown in colour with lighter oval spots over their bodies which can vary between burnt orange and olive green and are more vibrant as juveniles. Their heads are fairly blunt at the snout and wide at the ears. The underside is usually white with grey dots/lines in an irregular pattern. They have long pink tongues which graduates to a blue coloured forked tip. They frequently flick out their tongue when out and about utilising the Jacobson’s organ in the roof of their mouth to detect prey. The size of an adult monitor can vary, the longest being around the 5ft mark, the smallest being around the 2.5-3ft mark, with many falling in between. They are not sexually dimorphic so are difficult to sex as adults.

Where are Bosc Monitors from?

The Bosc or Savannah Monitor is, as the latter name suggests, a species from central and southern Africa, with range from as far west as Senegal and Gambia, through Mali, Niger and Chad, to as far east as Sudan and Ethiopia. They often dig deep burrows to retreat to in their natural habitat of savannah areas, as well as scrubs, and arid grasslands with hot dry summers and monsoon like winters. 

How do you keep Bosc Monitors?

As with all large Monitor species, they require a lot of space, time and patience to tame down. We ask that you seriously consider whether you can provide the animal with everything it requires for the duration of its life. They do not make good pets for families with young children, as even the most docile animal has the potential of mistaking fingers for food - a large monitor can and will have the potential to cause damage should it bite. It is our responsibility to ensure that you are well informed with regards to knowing what keeping a large monitor entails, we would rather put people off buying than sell these animals to unsuitable or irresponsible owners.

Bosc Monitors are mainly terrestrial, which means that wherever you house them the floor space needs to be that of considerable measurements, for an adult the minimum floor space required is something near to 2.4 x 1.2 x 1.2m (8ft x 4ft x 4ft). For juveniles up to 30cm long, a 120 x 60 x 60cm (4 x 2 x 2ft) vivarium is the absolute minimum. From an enrichment viewpoint, most Bosc Monitors will climb if given the opportunity. The addition of rocks, cork bark and branches to create multiple levels, hiding and basking areas will be readily enjoyed by these intelligent creatures. 

We recommend using a sand/soil substrate maintained at around 50-60% humidity. The substrate ideally needs to be as deep as possible - for an adult, it is recommended to provide at least 45cm (18”) depth to allow the animal to burrow should it choose to, for juveniles as deep as they are long is ideal. They enjoy wallowing in water, provision of a large enough dish or pool is important to aid hydration, and bathing often helps stimulate a bowel movement. For adults in custom built enclosures, many owners opt to add in a pool with drainage underneath to make cleaning easier.

Heating the enclosure adequately is extremely important, as these lizards come from hot and arid areas of Africa. As with all reptiles, this temperature gradient is essential so that the animal can properly regulate its body temperature (thermoregulate) and digest foods properly. 

The most common method for heating a large enclosure is to use a guarded basking bulb on a thermostat, often combined with Deep Heat Projectors or Halogens (again, controlled by thermostats.) For larger enclosures it is easier to achieve the desired temperature gradient which ideally needs to range from around 25°C cool end, surface temperatures averaging 32°C - 38°C with an isolated basking area of between 54°C - 65°C basking. 

At night time the lights should be turned off, or if room temperatures are lower than 25°C, a ceramic bulb on a thermostat should be set to ensure the temperature does not drop too low.

With regard to UVB lighting, there is still a lot of outdated information suggesting that monitor lizards do not require UVB but they absolutely do. These are an African Savannah species, requiring a Ferguson Zone of 4. UVB exposure plays a vital role from the synthesis of vitamin D3 and the absorption of calcium, to the regulation of circadian rhythm and behaviour and activity levels.

The feeding of Bosc monitors has been a long term cause of debate. It basically boils down to whether to feed mainly rodents or insects. Following post mortems performed on wild Bosc Monitors, it was found that they eat a very narrow range of prey. The bulk of their diet are invertebrates; almost exclusively crickets, locusts and grasshoppers, millipedes, beetles and snails. Compared to other African monitors, they have a more specialised diet - they are not attracted to carrion, and very rarely eat things such as birds eggs, rodents or other reptiles - which are easily found in the wild.

Captive Bosc Monitors are often morbidly obese, because they will eat almost anything offered - often through boredom and lack of environmental enrichment. They are highly intelligent, and will soon work out that it is easier to wait and be hand fed a rodent, than it is to chase insects. This vicious cycle often has owners ‘killing with kindness’ because they believe the animal will starve through not hunting insects and resort to feeding rodents. Wild Boscs are cyclic animals which go through a period of diapause, meaning that they only feed for around half the year as adults; so persevering with only offering insects will not harm the animal at all.

Offering insects such as crickets, locusts, cockroaches and earthworms, every day is recommended for juveniles, and 2-3 times a week for adults, with a mouse, raw fish or egg (raw or scrambled) as a treat every 2-3 weeks. For treat items, make the monitor work for it! This can be done by simply making the animal chase the prey on the end of tongs, or hiding it inside a paper bag to make them use their big brains to solve this problem. They are intelligent to the point that (with time and patience) they can be trained to touch certain objects to gain a reward.

Whatever you decide to feed your monitor, ensure that it is getting enough exercise. Bosc monitors can become morbidly obese if they eat too much with little exercise. Being obese can seriously shorten this lizard’s life span, which should be up to 25 years, down to anything as low as 5 or 6 years. If your Bosc Monitor does become obese, a few laps swimming around the bath every week will help, encouraging them to walk around out of the enclosure, alongside reducing the food intake.

On all live feeds, use a good quality dusting powder to provide an essential calcium and vitamin boost to your Bosc Monitor. The traditional method of application is to use a spare live food tub or empty cereal container to coat the insects lightly in whichever dusting powder you are providing. We’d advise dusting your insects on every feed, alternating between calcium and vitamin powders according to pack recommendations.

Please note: Our team reserves the right to refuse sale of this animal if we feel that the long term wellbeing or welfare is in question. Large monitor lizards come with challenges; from temperament to housing, equipment and upkeep costs. It is our responsibility to the animal to determine your experience levels and suitability; we apologise if this offends you, but our strict policies are in place for the protection of the animal to ensure it has the best possible life - animal welfare always comes before profit. 

Do your research
Before you commit to buying any pet, please do your own independent research.