Varanus salvadorii

Geographic Range

Papuan monitors are endemic to the island of New Guinea, both Papua New Guinea and West Papua (Indonesia).

• Biogeographic Regions
• australian australian
  • native native

• Other Geographic Terms
• island endemic island endemic

Habitat

Papuan monitors primarily reside in coastal lowland environments, mainly tropical rainforests and mangrove swamplands. Though they are typically found from sea level to 200 meters above sea level, these animals may be found in mountains up to 650 meters above sea level. They live in arboreal and terrestrial habitats, depending on availability of sunlight and prey. Since this species resides in rainforests, its optimal temperatures are high, from 29-31ºC during the day.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• rainforest rainforest

Physical Description

Papuan monitors are the largest known species of monitor lizard found on New Guinea, growing up to 2.5 m, with an average weight of 20 kg. They have long tails, typically twice their SVL (snout-vent length), which are rounded at the base and triangular distally. The skin is covered with non-overlapping scales, and body color is mostly black with specks of yellow, white, or green, with folds around the neck. They have round snouts with long, forked tongues used for chemoreception, and very long, vertical teeth, as well as strong claws. Males are generally larger than females, due to reproductive energy expenditures by femmales.

• Sexual Dimorphism
• male larger

Development

There is no data regarding mating behavior or development of this species in the wild, but it has been studied in captivity. Egg clutches of 4-12 eggs are laid between August and January in a well-hidden hole (dug by the female). Most eggs are infertile in captivity; only four fertile clutches have been documented. Humidity and oxygen levels (altitude) appear to be important factors in egg development. Weight and dimension of eggs, as well as hatchlings, is widely variable (47-68 g and 42-49 cm, respectively); the reason for this is unknown.

Reproduction

Male Papuan monitors are aggressive, fighting (as all vanarids do) in a ritualized fashion that involves head weaving, bipedal clinching and wrestling in order to attract females; the larger a male is, the more likely he is to succeed. After combat, males will proceed in courting the female (by licking, stroking and scratching in other varnids), followed by a forceful act of mating, with the male biting the female's neck, resulting in bleeding wounds called mating marks. The female will then either comply, lifting her tail to allow the male to insert his hemipenes (one at a time, though both are used in one mating) or flip over in order to make copulation more difficult, if not impossible. Generally, female vanarids may mate with one or several males over a period of a few days.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

Breeding season is unknown and this behavior has not been observed in the wild. In captivity, when a male is introduced to a female, copulation nearly always takes place and eggs result. In general, varanids may lay more than one clutch of eggs per year and captive clutches of Papuan monitors typically have 4-12 eggs (although the majority of these in captivity are infertile). Size of the female seems to be linked to clutch size, with larger females producing more eggs. In captivity, eggs laying has been observed 3-4 months after copulation, with hatching taking place 20 or so days later. Male and female Papuan monitors experience varied growth patterns that illustrate this species' level of sexual dimorphism. Upon reaching sexual maturity (within 2 years of hatching), males continue to grow, whereas growth of female individuals is halted, with energy being diverted to egg production.

• Key Reproductive Features
• iteroparous iteroparous
• sexual sexual
• fertilization fertilization
• oviparous oviparous

Little is known about parental involvement of Papuan monitors after eggs have been laid. Following copulation, captive females have been noted to bury their eggs, digging holes and then filling them in such that the nests are barely visible.

• Parental Investment
• female parental care female parental care
• pre-fertilization
  • provisioning

Lifespan/Longevity

Lifespan of Papuan monitors in the wild is unknown. In captivity, they are known to survive for 12-20 years.

Behavior

Papuan monitors bask in the sun throughout the day. They are temperature sensitive and, when their body temperature exceeds temperatures of around 38ºC, body contractions aid in lowering body temperature. They are extremely agile, using their long tails to aid in balance as they jump amongst branches, and use contractions of their throat muscles to pump oxygen into their lungs when they need to move quickly and suddenly. They are known to exhibit a warning posture, in which they carry their tails rolled up behind them.

• Key Behaviors
• arboreal arboreal
• terricolous
• diurnal diurnal
• solitary solitary

Home Range

No information has been recorded on the home range of Papuan monitors due to the lack of observation in the wild. A closely related species, Varanus komodoensis , has been observed to have a home range of 2-3 km^2.

Communication and Perception

In general, varanids are known have well-developed auditory and visual systems. The tongue aids in chemoreception and olfaction, bringing air into the mouth and pressing it up against the large Jacobson's organ, which contains specialized chemoreceptors. This aids them in detecting food sources. Papuan monitors communicate with each other visually (movements such as head weaving during combat), through touch (during courtship behavior), and sound, hissing for short periods throughout a broad frequency span as a warning.

• Communication Channels
• visual visual
• tactile tactile
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• vibrations vibrations
• chemical chemical

Food Habits

Papuan monitors are carnivorous, feeding on small animals. They are known to prey on both adult birds and their eggs (particularly Cacatua sp. and maleos ( Macrocephalon maleo )). They are also known to eat small mammals (such as rodents), reptiles and amphibians, and insects, as well as carrion. They have long, sharp teeth and powerful jaws, and are known to swallow food items whole. Unlike many other varanids, they do not appear to adjust the ferocity of their attack based on prey size.

• Primary Diet
• carnivore carnivore
  • eats terrestrial vertebrates
  • eats eggs
  • insectivore insectivore
  • scavenger scavenger

• Animal Foods
• birds
• mammals
• amphibians
• reptiles
• eggs
• carrion carrion
• insects

Predation

Little is known about possible predators of Papuan monitors. As they are thought to be top predators in their habitat, humans likely pose the only regular danger to these lizards, due to deforestation and the value placed upon their skins.

Ecosystem Roles

Papuan monitors are large, powerful creatures that are the dominant predators in their ecosystem, with no known predators besides humans. They are predators of many smaller animals and their eggs, controlling the populations of these organisms. Wild caught Papuan monitors have been found to be infected with enteric parasites.

Economic Importance for Humans: Positive

Papuan monitors have been utilized by natives of the island for their meat and skin, which is important as clothing and as heads for ritual drums. They are not often actively hunted, due to the inherent risks associated with finding and killing these large animals, but are often caught in traps intended for other animals.

• Positive Impacts
• food food
• body parts are source of valuable material

Economic Importance for Humans: Negative

Many of the animals that are prey for Papuan monitors are important to island natives for food and economic purposes. Also, attacks on cattle and other livestock are not uncommon. If disturbed by humans, these lizards are capable of doing severe physical damage.

• Negative Impacts
• injures humans
  • bites or stings

Conservation Status

This species has not been evaluated by the International Union for Conservation of Nature and Natural Resources. It is listed in Appendix II of CITES, indicating that while they are not yet considered threatened or endangered, trade of these animals must be closely controlled.

Additional Links

Encyclopedia of Life

Contributors

Gregory Wojtasek (author), The College of New Jersey, Matthew Wund (editor), The College of New Jersey, Jeremy Wright (editor), University of Michigan-Ann Arbor.

References

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