Varanus salvadorii

Varanus salvadorii

Varanus salvadorii, also known as Salvadori's monitor, Crocodile monitor, Papua monitor, or Artellia, is a monitor lizard is found in mangrove swamps and coastal rain forests of southeast New Guinea. It is speculated that the creature can grow to a length of 15 feet (4.75 metres) or even 18 feet (5.5 meters), which would make it the longest lizard in the world, but to date the longest recorded specimen is 11.5 feet in length. Most of this length is made up of the tail, which accounts for more than 60% of the animal's length. At birth V. salvadorii is about 18 inches (45 cm) long, while a sexually mature female may grow to 5 feet (1.52 meters). Because it has not been extensively studied, specific details about the monitor are unknown.

Taxonomy

V. salvadorii was first described as Monitor salvadorii by Wilhelm Peters and Giacomo Doria in 1878 from a female specimen with a snout-to-vent length of 19 inches (48 cm) long and a tail measuring 45 inches (114 cm) in length. The generic name Varanus is derived from the Arabic waral (ورل), which translates as "monitor" in English. The specific name is derived from a Latinization of Tommaso Salvadori, an Italian ornithologist who worked in New Guinea. Later, in 1885, it was renamed Varanus salvadorii by George Albert Boulenger. The monitor's closest cousins are the Komodo dragon (V. komodoensis) and the Lace goanna (V. varius). The Papua monitor is occasionally confused for the Water monitor (V. salvator) because of their similar scientific names.

Distribution

The largest of the seven species of monitors found on New Guinea, it is found in both the Republic of New Guinea and the northern region of the Indonesian Province of Irian Jaya. It inhabits the high and low canopies of the lowland rainforests and coastal mangrove swamps, sometimes venturing out of these areas during floods in the rainy seasons. No detailed field investigation data is available for the Papua monitor, so the extent of its range is unknown.

Description

The body of the lizard is dark green with rings of yellow spots. The tail is banded yellow and black. It has a bulbous snout that lends it the name "tree crocodile." It has long straight teeth and prominent curved claws. There is no external sexual dimorphism. Unique among living varanid species, the animal's tail is two-thirds longer than the snout-to-vent length in both juveniles and adults.

Behavior

V. salvadorii is an arboreal lizard. As such, it can hang onto branches with its rear legs and occasionally use its tail as a prehensile grip. The primary use of the tail, however, is to counterbalance its weight when leaping from one branch to another. The tail may also be used for defense, as captive specimens have attempted to whip their keepers with their tails. This species is occasionally seen in the pet trade, but has earned a reputation of being aggressive and unpredictable and thus only suitable for the most advanced keepers.

The monitors will rise up on their hind legs to check their surroundings, a behavior that has also been documented in Sand goannas (V. gouldii). According to native belief, they will give a warning call if they see crocodiles.

Diet

V. salvadorii's upper teeth are long and fanglike, designed to hook into fast-moving or feathered prey such as birds, bats, and rodents. Its lower teeth are housed in a fleshy sheath. In the wild it is the top predator on New Guinea, feeding on birds, eggs, small animals, and carrion. There are also reports from natives that it may take down pigs, deer, and hunting dogs, and that the monitor hauls its prey into the canopy to consume it. Its only competition is the New Guinea "singing dog", a feral dingo. Captive specimens have been known to eat fish, frogs, rodents, chickens, and dog food.

In general it avoids human contact, but their bites are capable of causing infection, like the Komodo dragon's. One fatality is reported from a bite in 1983 when a Papuan woman was bitten and later died from an infection.

Reproduction

Reproduction has only been observed in captivity, so nothing is known about its reproduction in the wild. The egg clutches, comprised of four to twelve eggs, are deposited around October to January, with the eggs showing a remarkable difference in dimensions, a phenomenon for which no explanation is known. Dimensions may vary from 7.5x3.4 cm (3.0x1.3 in) to 10x4.5 cm (3.9x1.8 in), while weight may vary from 43.3 to 60.8 grams (1.53 to 2.14 oz). Most clutches laid so far are infertile, and there have only been four successful breedings documented thus far. Hatchlings are about 18 inches (45 cm) long and weight around 56 grams (2.0 oz).

Conservation Status

V. salvadorii is currently protected under the Convention on International Trade of Endangered Species (CITES) agreement, but is not listed in the Endangered Species Act. It faces threats from deforestation and poaching as it is hunted and skinned alive by tribesmen to make Kundu drums. The species is maintained at 17 zoological parks worldwide. The total U.S. captive zoo population totals 52 individuals and an unknown number in private collections.

References

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