Crocodile Monitor

## About

A crocodile monitor in a tree.

The crocodile monitor ***(Varanus salvadorii)*** also known colloquially as the tree crocodile, is a monitor lizard species native to the island of New Guinea. crocodile monitors are are a darkish grey-green in colour and are mottled with spots and stripes of bright yellow, white or pale green. The colourations and patterns of an individual may vary by region of origin. Crocodile monitors have characteristically rounded snouts and slender bodies with non-overlapping scales and very long tails. They also possess triangular backwards-facing teeth which are very long comparatively to the rest of the skull. they also have long forked tongues, characteristic sensory organs used for chemoreception by all monitor lizard species. They can grow to an astounding 2.5-3.25m (8.2-10.6ft) and can weigh up to 20kg (44lbs) making them the largest lizard species endemic to New Guinea. Males usually exceed females in length and weight. One individual reported from Port Moresby, Papua New Guinea was said to have reached a length of 4.75m (15.58ft) however, this report is unverified and likely fabricated or exaggerated.

## Diet

Crocodile monitors are carnivorous and also the apex predators of Papua New Guinea. They hunt and consume a variety of small species, such as rodents, bats, bandicoots, various reptiles and amphibians, insects and birds like maleo ***(Macrocephalon maleo)*** and cockatoos as well as their eggs. Despite their large and very sharp teeth, crocodile monitors swallow their food whole. It has also been reported by Papuan locals that a large crocodile monitor is able to subdue prey like livestock such as pigs, as well as deer. Unlike most monitors, which employ an ambush hunting method, the crocodile monitors anticipates its prey fleeing, running towards it while it attempts to escape head-on.

## Conservation Status

The crocodile monitor is currently considered least concern by the IUCN however, the species still faces some minor threats. Deforestation and the illegal pet-trade are the largest threats to the species currently, with the habitat degradation of Papua New Guinea become quite severe in recent years. Though deforestation is destroying vital habitat for multiple Papuan species, the crocodile monitor is largely unaffected, due to its currently widespread population. The illegal pet-trade is largely non-threatening to the species however, some crocodile monitors have likely been taken by the trade.

## Range and Population

The crocodile monitor inhabits much of the island of New Guinea, where its range extends from the eastern coasts of West Papua, Indonesia to the southern and western most areas of the island. The species inhabits the tropical rainforests, lowlands and mangrove swamps of New Guinea, occurring almost exclusively in areas undisturbed by human activity. Crocodile monitors have also been known to have a preference for habitats near water sources, favouring floodplains and riparian woodlands however, above all they prefer to live in low canopies, being an arboreal species. Crocodile monitors live at relatively high elevations, being prevalent on mountains up to 650-750m (2,132-2,460ft) above sea level. An enigmatic species, the crocodile monitor's exact population is unknown however, it has been labelled "less common than other large monitors." By the IUCN.

## Behaviour

The crocodile monitor spends most of its time basking throughout the day, using contractions to lower its eternal body temperature if it exceeds 38°C. They will use these same contractions in their neck muscles to pump their lungs harder when chasing prey in order to move more efficiently. Crocodile monitors are also surprisingly agile and are known to jump from tree to tree quickly and swiftly in the canopy. In breeding and courting behaviour, male monitors are highly aggressive, fighting one another in an effort to attract the females in the area. The fighting involves head waving, standing bipedally and wrestling and the larger male often wins. When courting, a male will stroke, scratch and lick the female in an effort to coheres her into mating. In compliance, the female will raise her tail, inviting the insertion of the male's hemipenes however, if she does not wish to mate, she will flip herself over, making intercourse difficult or impossible. When mating, the male will forcibly bite the females neck, causing deep incisions known as "mating marks". Egg laying has been observed to occur around 3-4 months after the initial copulation and clutches of 4-12 eggs have been witnessed in captive individuals. It is likely that individual female size relates to the among of eggs laid, with larger females produces larger clutches. Eggs may hatch as soon as 20 days after being laid. Through maturation, the sexual dimorphism of this species is demonstrated, seen mostly in the continued growth of male individuals following reaching sexual maturity, whereas conversely, females will halt growth, diverting energy to egg production.

### Relationship with Humans

Crocodile monitors are seen as pest species by farmers, as they have been known to attack cattle and other livestock quite frequently. Beyond this conflict, crocodile monitors are incredibly important species to the native Papuan peoples, their hide and meat being valued among locals as clothing and food respectively. Their heads are also often used to comprise traditional ritualistic drums. Despite their importance in goods, the crocodile monitor is not often hunted, mostly due to the species' enigmatic nature and hunting difficulties. They are however, sometimes ensnared in traps left for other species. Crocodile monitors are also infamous for their aggressive nature and often attack humans when threatened. Though the species is not venomous, its sharp teeth easily cut through human skin, leaving deep cuts which are susceptible to bacterial infections.

## In Captivity

The crocodile monitor is quite common in captivity and is housed internationally. Notable zoos which exhibit this species include; the Cincinnati Zoo, Chester Zoo and Samjung The Park in the US, UK and South Korea respectively. The crocodile monitor is also common place in zoos and tropical-centric exhibitions across Europe, in countries like Russia, Ukraine and Czechia. Oddly enough, the crocodile monitor has also begun to become popular in the herping community and many own them as exotic pets. When caring for a crocodile monitor, it is important to understand that they are wild animals and that an accurate and suitable environment, space, diet and temperature are all provided. It is recommended by crocodile monitor owners that they should be housed in large outdoor quarters, more similar to zoo enclosures than the average terrarium. Despite their common status in reptile keeping, it is advised that beginners do not attempt caring for and housing crocodile monitors, for abundantly clear reasons.

## Sources

* IUCN Red List of Threatened Species - https://www.iucnredlist.org/species/42485775/42485784
* Crocodile Monitor | Wikipedia - https://en.wikipedia.org/wiki/Varanus\_salvadorii
* Crocodile Monitor | Animal Diversity Web, University of Michigan museum of Zoology - https://animaldiversity.org/accounts/Varanus\_salvadorii/
* Crocodile Monitor | Smithsonian's National Zoo & Conservation Biology Institute - https://nationalzoo.si.edu/animals/crocodile-monitor
* Crocodile Monitor | ZOOINSTITUTES - https://zooinstitutes.com/animals/crocodile-monitor-1701/
* Crocodile Monitor | Reptile Rapture - https://reptilerapture.net/crocodile-monitor-caresheet.html