Bosc Monitor (Varanus exanthematicus)

by Bruce Jones

Area of Origin – Africa

General – The Bosc monitor can reach a total length of 3-4 feet and specimens have been recorded even larger, however they will generally reach 2 ½ to 3 feet in length. They are diurnal and will be active during the day. They become very tame and have distinct personalities and characters. They can live in excess of ten years and if correctly cared for they can reach an age of 20 years.

Suitability – Intermediate.

Housing – As bosc monitors are large and heavy bodied animals, they require a large and solid vivarium. The minimum size vivarium should have a floor space of 5x3 feet, larger is better. Young lizards can be kept in their long term vivarium or you can grow them on in a smaller enclosure. Young lizards will spend most of their time hiding, so be sure to provide plenty of cover and hiding places. Cork bark works well for this purpose as they can hide inside the bark and is great for climbing. There should be a raised branch or a hide which the lizard can climb on which should be close the spot bulb to allow the monitor to thermo regulate at its discretion. All décor should be secure to prevent injury. An adult monitor’s cage should have minimal decor as they are very powerful lizards and will easily move the decor around. Java wood and cork bark is ideal to be used for adult monitors and should be securely fixed to prevent the lizard from injuring itself. There should be a hide large enough for the monitor to use. There should also be access to fresh, clean water and they enjoy bathing in water so a large water receptacle should always be present.

Temperature – The monitor should have access to a basking area with a temperature of 35c and a cool end with a temperature of around 20c. Using a dimmer stat makes it possible to maintain the ideal temperature and create a temperature gradient.

Lighting – There are several schools of thought on whether Bosc’s require UVb light, but we prefer to use it, as they come from the African Savanah where they would naturally be exposed to high levels of UV light for the most part of the day. This lighting is required to help them produce vitamin D3, which allows their body to absorb calcium. A strip tube which emits UVb should be used, either 10-12%. This should be replaced once per year as the UVb will decrease over time.

Humidity – Boscs aren’t particularly fussy about the relative humidity in their vivarium but it is a good idea to spray the substrate every couple of days and to give the vivarium a light spray. It also recommended to spray the inside of one of their hides so that they have the choice of burrowing into a damp substrate which can aid in shedding.

Buying Tips – Ask to handle the bosc to gain and idea of its health, condition and temperament. A healthy young bosc will thrash around, hiss and possibly even bite; but this isn’t any cause for concern and is a good indication of a healthy specimen. Look for taught skin, clear bright eyes and no signs of faecal staining around the vent. A healthy Bosc should move around easily and have no deformity of the legs.

Varieties – There aren’t yet many colour morphs in the Boscs monitor, but as they become more commonly bred in captivity the number may increase. At the moment there are Hypomelanistic and Albino specimens although these are still very rare.