They are found in west and central regions of Africa from Senegal eastward to Sudan and southward to Northern Zaire almost reaching the Congo River and Rift Valley.
This ground-dwelling species usually find shelter in burrows, but being good climbers juveniles are sometimes found in low trees, and bushes.
The savannah monitor belongs to the subgenus Polydaedalus, which include other monitors such as the Nile monitor (Varanus niloticus) or the Ornate monitor (Varanus ornatus).
Like their name indicates their preferred habitat is the African savannah. But the species occupies a variety of habitats and is also found in rocky deserts, grassland forests, open forests, and woodlands.
These monitors aren't usually found in the rainforest or dry desert. These shy animals will also avoid more populated areas, and when they do encounter humans they may play dead in an attempt to avoid capture.
Savannah monitors are diurnal and most active when the sun is out and it's warm. In cooler weather or periods of drought, these lizards become mostly dormant.
That's why during the 8 months long wet season they will eat large amounts of food when it's most plentiful. This will give them the necessary fat reserves to sustain them during the dry season when food is scarcer.
Savannah monitor males are quite territorial and will defend their territory very aggressively. They show their aggression with loud hissing sounds and trashing the tail, before striking at their opponent. If need be they will wrestle and bite each other and can inflict quite severe injuries to each other.
With 5 subspecies their size and descriptions found in the literature is quite variable. Males are considerably larger than females.
Their maximum size is usually placed between 3.5 and 5 feet (105 / 155 cm), even though some source consider they can reach up to 2 m in length.
But the average size of most wild specimens is normally between 2 or 2.5 feet. The Savannah monitor has a stout body, with a short neck and wide head with the nostrils located midway between the tip of the snout and the eyes.
Their head can be turned in all directions, while the skull and dentition are adapted to feed on hard-shelled prey such as snails. Just like snakes they have a blueish forked tongue and are also capable of expanding their mouth, enabling them to swallow larger prey items.
The tapering tail is laterally compressed and covered in alternating brown and yellowish rings and has a double dorsal ridge. They have relatively short limbs and toes, and the caudal scales are keeled.
Their coloration varies according to the local environment. These lizards are normally grayish to brown in color, with the back covered with rows of circular shaped, dark edged yellowish spots. While their underside and the inside of the limbs is yellowish in color.
Subspecies / Taxonomy / Etymology
The Savannah monitor has 5 subspecies currently recognized.
The species specific name "exanthematicus" derives from the Greek word "exanthem", which means meaning a blister or eruption of the skin.
They were originally described has Lacerta exanthematicus by the French zoologist and botanist Louis Augustin Guillaume Bosc in 1792. This name was given as a reference to the large oval scales found on the back of their neck.
Diet / Feeding
The savannah monitor as a varied diet that includes arthropods such as beetles, crickets, centipedes, millipedes, scorpions and mollusks like snails. But they will also eat small mammals, birds, reptiles such as snakes or other lizards, toads, eggs and even carrion.
As adults they eat a very large quantity of snails, they have quite blunt teeth which help them crack the snail's shell. Their jaw has also evolved to apply the maximum force at the back of the jaw to further help in crushing snail shells.
Juvenile specimens are mostly insectivores since they lack the teeth to be able to eat snails.
The Savannah monitor uses a feast and fast feeding system. During the wet season which lasts for about 8 months, these lizards will feast gorging on plentiful and easy to find food. In the wet season, they can consume up to 1/10 of their own body weight in a single day.
While in the dry season savannah monitors live off fat reserves they have built up during the wet season feasting.
The Savannah monitor breeding season, as well as the feasting period occur during the wet season. When males find a suitable female mate they will follow them around relentlessly.
The male courtship display includes head nodding, and occasionally some bites and scratching with his claws to the female's neck and legs. Eventually, the female allows the copulation to take place, which can last for several hours.
About one month after mating females lay anywhere from 10 to more than 50 eggs. Females may claim abandoned mammal burrows or dig the 1,5 m deep nest herself, occasionally females use termite mounds to lay their eggs.
The nest keeps a constant incubation temperature of 29 or 30°C. The incubation period lasts for 5 or 6 months, and the eggs hatch usually in March. The savannah monitor eggs have an unusually high hatch rate around almost 100 %.
The hatchlings have a total length of about 130 mm and weigh on the average around 20 g. However juveniles will grow very quickly during the first 2 months, and at about 1 months of age, these small monitors start hunting food, mainly insects.
Conservation status and main threats
Savannah monitors are listed as Least Concern by IUCN, they are also listed on CITES Appendix II. They are hunted for food and also used in traditional medicine in some West African countries.
They are also killed for their skin and collected for the pet trade. Even though these lizards are the most common Varanid species in the exotic pet trade, their exploitation is considered sustainable.
Species: V. exanthematicus