Note: Please see The Monitor Lizards (Family Varanidae) – Family Overview and Species Accounts
for information on the natural history of monitor lizards.
Storr’s Pygmy Monitor, Varanus storri
This is the smallest monitor regularly available in the pet trade. Also nearly the tiniest member of the family Varanidae, this species has much to recommend it as a “first monitor”. Reaching just 14 inches in length, Storr’s monitor is one of the only monitors that can be housed within an aquarium-sized (see below) enclosure when adult.
A Popular Pet
Storr’s monitors are immensely popular because they combine all of the typical monitor traits in a small package – indeed, they act exactly like tiny versions of their larger cousins. What they lack in size is more than made up for in attitude, and they are quite bold as captives. In fact, keeping more than one in a cage, even a mated pair, is difficult due to their aggressive natures.
This plucky, brown little lizard hails from northeastern Australia. A subspecies, reddish in color but otherwise similar (V. s. ocreatus) ranges further west. In the eastern part of its range, Storr’s monitor is threatened by the introduced marine toad, which both preys upon and competes with it. Populations have all but disappeared from some areas already.
Storr’s monitors are quite active and should be housed in a tightly secured aquarium of at least 30 – 55 gallons (“long models are best”). They require a source of UVB light and a basking site that reaches 90 F or so.
Although they are often fed pink mice and small rodents in captivity, the natural diet of this species consists largely of insects. The bulk of their food in captivity should be roaches, crickets, waxworms, super mealworms, mealworm beetles and wild-caught insects. Canned insects, such as silkworms and grasshoppers, offer an excellent source of dietary variety. Many individuals also accept canned monitor diets.
Captive breeding is possible, but pairs must be watched closely for aggression. The 2-5 eggs hatch in 100 days at 82F.
Crocodile Monitor, Varanus salvadorii
At the other end of the spectrum from Storr’s monitor is southern New Guinea’s massive crocodile monitor – it approaches 9 feet in length (nearly as long as, but much lighter than, the Komodo dragon), and there are unverified reports of much longer individuals. The prehensile tail is twice as long as the snout-vent length. Crocodile monitors are black in color and boldly marked with yellow spots, and sport long claws and a bulbous snout (particularly so in mature males).
Highly arboreal despite their size, crocodile monitors dwell in the canopies of lowland forests in the vicinity of rivers and mangrove swamps. Little is known of their status in the wild, but there is concern given the limited range; the species is listed on CITES Appendix II.
In contrast to the other lizards described here, crocodile monitors are suitable only for very advanced hobbyists, or as zoo animals. Those I worked with learned to tolerate my presence, but remained wary and agressive even after many years.
In contrast to the usual structure of monitor teeth, those of the crocodile monitor are serrated and over-lapping – possibly an adaptation to holding onto and carrying large prey high above the forest floor. These animals are formidable predators, and capable of inflicting potentially life-threatening wounds.
Captive-bred animals are available and adjust moderately well (please see above) if given huge, high-topped enclosures that accommodate their arboreal lifestyles – forcing crocodile monitors to remain on the ground is, in my experience, quite stressful to them.
A cage or room of 10’ x 10’ by 10’ would be required for a single adult. UVB light and a basking spot of 90-95 F are needed. A humid environment is preferred, but they must be able to dry off as well.
Wild crocodile monitors feed upon cuscus, young tree kangaroos, naked-tailed rats, bandicoots, bats and other mammals, birds and their eggs, frogs, snakes, lizards and carrion. Captives do well on rats, mice, chicks, crayfish, large roaches and hard-boiled eggs.
Image referenced from Wikipedia.
Check back on Friday for more Monitor Species Profiles.