The Desert monitor (Varanus griseus ) is a species of monitor lizards of the order Squamata.
Desert monitors normally display a variety of body colorations from light brown and yellow to grey. These lizards can also have horizontal bands on either their backs or tails, along with yellow spots across their backs. Their young are normally a brightly colored orange and have distinctive bands across their backs which may be lost as they mature. Their nostrils are slits located farther back on their snouts (closer to the eyes than the nose), and their overall body size is dependent on the available food supply, the time of year, environmental climate, and reproductive state. Males are generally larger and more robust than females, but females have a more gentle look about them. Those differences allow males to be distinguished from females from a distance without careful inspection. Adult monitor lizards also go through periods of molting in which they shed their outer layer of skin to expand their overall body size. This process can take several months and happens around three times per year.
Desert monitors are found throughout North Africa and Central and South Asia. They inhabit dry sandy deserts, dunes, and steppe-like grasslands. They can also be encountered at the edges of cultivated areas and rural gardens.
Desert monitors are solitary lizards that maintain large territories. During the middle of the day, they mainly stay in their burrows and only come to the desert surface to search for food. They are strong diggers and can easily build burrows that are several feet long. The skin of these monitors is adapted to the desert environment where they live, and they are excellent swimmers and divers and may even enter the water occasionally to hunt for food. They are also quite fast and able to run at a speed of 100-120 meters per minute. When running, they raise their bodies high and do not touch the ground with their tails. But monitor lizards can run fast for a short time, and usually move quite slowly. Monitor lizards can climb low trees and bushes and can jump from a height of more than half a meter. When meeting a human or another enemy from which it cannot escape, the monitor greatly inflates its body, as a result of which it greatly increases in size, hisses loudly, sticks out its tongue, and, opening its mouth wide, tries to bite. It whips its tail with force to the right and left, not allowing itself to be taken. Its bites are quite painful - the animal clings to the enemy and its sharp teeth penetrate deep into the wound. Desert monitors go into hibernation from about September to April. In April is a mass exodus from their hibernation, and they become most active between May and July.
The possibility of venom in the genus Varanus is widely debated. Previously, venom was thought to be unique to Serpentes (snakes) and Heloderma (venomous lizards). The aftereffects of a Varanus bite were thought to be due to oral bacteria alone, but recent studies have shown venom glands are more likely in the mouths of several if not all of the species. The Desert monitor has not yet been specifically tested, but its bites have shown aftereffects consistent with the venomous bites from other varanid lizards. The venom can be used as a defensive mechanism to fend off predators, help digest food, sustain oral hygiene, and possibly help in capturing and killing prey.
Desert monitors are carnivores. Their preferred prey is mice, eggs, or fish, but they will also hunt smaller mammals, reptiles, birds, amphibians, insects, or other invertebrates.
The breeding season of Desert monitors takes place between May and July. Females normally lay up to 20 eggs from the latter part of June through the beginning of July. They excavate burrows for their clutches and actively defend them from other individuals of their own species. The eggs are incubated at temperatures from 29 to 31 °C and hatch after an average of 120 days. At birth, the baby lizards have a total length of around 25 cm (9.8 in); they hatch fully developed and don’t require parental care. Young male Desert monitors become reproductively mature at 3-4 years of age, while females are to breed when they are 4-5 years old.
Desert monitors are not threatened at present, although in some areas a great deal of the land has been turned into farmland, which puts pressure on the species. Around 17,000 skins of these lizards are involved in commercial trade every year. In northern Africa, central Asia, and parts of India, Desert monitors are unprotected from hunting laws and are still hunted commercially.
The IUCN Red List and other sources don’t provide the number of the Desert lizard total population size. Currently, this species is classified as Least Concern (LC) on the IUCN Red List but its numbers today are decreasing.
