Pet Monitor Lizards (Varanidae): Like Giant Snakes With Legs!
Many characteristics of monitors remind one of snakes. The motion is slithering, although these lizards possess four muscular extremities. The deeply cleft tongue is continually stretched out to take up scent particles. When the throat is expanded, large pieces of food can be swallowed whole. Moreover, they display some mutual anatomic features that suggest their kinship with snakes, particularly to the giant snakes.
The monitor family contains the largest lizards, ranging from the Komodo dragons, which can be as long as 10 feet (3 m), to the “dwarfs” of scarcely 12 inches (3 cm). Just considering the smaller ones, species native to Australia are not in trade because strict laws forbid their export. As a consequence, all monitors are listed in WA II C2. Differences between sexes: It is seldom possible to tell the gender of monitors from external characteristics, such as the insignificantly fatter skull and the thicker tail base of the male. The only sure way is examination with a probe. Often both tips of the hemipenis will protrude during the passing of feces.
Reproduction: The eggs — there may be as many as 50 — are buried in the earth; in its natural habitat, the Nile monitor lays them in a termite mound. In the terrarium the clutch of newly laid eggs must be transferred to the incubator so that they do not fall prey to the predatory parents. All the larger monitors are predators and are particularly eager for the eggs of crocodiles and turtles. The maturation period lasts for about 110 to 200 days at 84°F (29°C).
Advice for general maintenance: Most monitors are solitary; keeping several in a terrarium therefore depends on individual behavior. A sliding partition for separating the animals should therefore be part of the terrarium plan and arranged in advance. Not to isolate the animals completely, a side of screen is recommended because visual contact and a chance for tongue touching will facilitate recombining the lizards later.
Water-dependent species need roomy swimming containers, which should measure in length at least twice the head-torso measurement of the largest lizard, in width one-half the head-torso measurement. When you are keeping large animals, you are well advised not to use a floor medium because the splashing of the water from the swimming pool and the usually energetic flight through the water will soak the terrarium floor. And then, too, the water will stay free of floor medium. If egg-laying is anticipated, then a container with suitable material must be introduced.
Warning: Be particularly careful in dealing with monitors: they can give you very deep bites. Newly introduced animals are especially frightened and move terrifically fast. They can escape while you are working in the terrarium and then must be captured again. A monitor that feels itself threatened not only uses its teeth as weapons but also its tail and claws. The climbing species have particular sharp claws and can inflict their keepers with wounds that take a long time to heal.
Varanus niloticus (Linnaeus, 1758)
Endangered species regulation: WA II C2
Total length: 80 inches (200 cm). Head-torso length: 32 inches (80 cm).
Distribution and Description: Africa south of the Sahara.
Habitat: Thin forests, savannahs, and steep banks, always in close vicinity to water.
Identifying characteristics: Slender head. Nostrils somewhat in the middle between the end of the snout and the eye.
Behavior: Diurnal. Inhabits water, ground, and trees. Solitary.
Maintenance: Water terrarium. 80 x 60 x 60 inches (200 x 150 x 150 cm), for one male and one female.
Decoration: Branches for climbing. For young animals only, plants from Africa. Sunning places and UV lighting.
Temperature: By day 77° to 86°F (25 – 30°C); by night 64° to 68°F (18 -20°C).
Humidity: 70 to 90 percent. Food: In the juvenile phase, insects; later, freshwater fish, mice, rats, chicks, eggs; in natural habitat also reptiles, amphibians, and large snails.
Varanus e.xanthematicus (Bosca. 1792)
Endangered species regulation: WA II C
Total length: 60 inches (150 cm).
Head-torso length: 28 inches (70 cm).
Distribution and Description: In many subspecies Africa, south of the Sahara, but not West Africa.
Habitat: Dry savannahs, briary plains, rocky landscapes, also in higher elevations.
Identifying characteristics: Head short and plump. Nostril directly in front of the eye.
Behavior: Diurnal. Lives in the ground, in rock heaps, boulders. Likes to dig. Solitary.
Maintenance: Shallow terrarium, 80 x 60 x 40 inches (200 x 150 x 100 cm), for one male and one female.
Decorations: Sandy floor, no pebbles, which would be flung against glass. Well-fastened stone piles and clay pipes sunk into floor for caves, stumps. Small water container or keep the floor of the caves damp. Sunning places and UV lighting. Sun terrarium.
Temperature: By day precisely 77° to 95°F (25 – 35°C); by night 59° to 68°F (15 – 20°C). For animals from the southern distribution area, pseudo-winter rest from November to February at 59° to 68°F (15 – 20°C; reflector lamps not turned on).
Humidity: 50 to 80 percent.
Food: In the juvenile phase, insects; later, mice, rats, chicks, eggs, and after becoming accustomed to them, freshwater fish.