The black tree monitor or Beccari's monitor (Varanus beccarii) is a species of lizard in the family Varanidae. The species is a relatively small member of the family, growing to about 90–120 cm (35–47 in) in total length (including tail). V. beccarii is endemic to the Aru Islands off New Guinea, living in an arboreal habitat. The skin color of adults is completely black, to which one common name refers.
The generic name Varanus is derived from the Arabic word waral (ورل), which translates as "monitor" in English. Its specific name, beccarii, is named after the Italian explorer Odoardo Beccari.
An insectivore is a carnivorous plant or animal that eats insects. An alternative term is entomophage, which also refers to the human practice of e...
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TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
Oviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
Precocial species are those in which the young are relatively mature and mobile from the moment of birth or hatching. Precocial species are normall...
Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some anima...
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starts withHatchlings and juveniles of V. beccarii are a dark grey in colour, with regular rows of bright yellow-green dots which are particularly noticeable on their backs. As they mature, they turn completely black, losing the colourful dots. Fully grown specimens reach 90–120 cm (35–47 in) in overall length (including tail), with the males slightly larger than the females.
The black tree monitor is generally well adapted for living in trees. Its tail is particularly long, sometimes two-thirds of the overall length, and is used in a prehensile manner to stabilize the animal in the branches. In fact, the tail is used solely for this purpose, as the animal does not evince the defensive tail-lashing behaviour seen in other monitor species. Like other tree monitors, they sport some of the longest and most slender forelimbs of all monitors, which end in elongated digits tipped with large claws and adhesive soles, helping it maintain grip in the trees and catch prey. It also has unusually long teeth for a monitor of its size, which may help it to hold on to prey it catches in the canopy. In the wild, the black tree monitor is reported to be nervous and high-strung; it will flee if threatened, and if handled carelessly, will bite, scratch, and defecate on the offender.
V. beccarii is native to the Aru Islands in Indonesia, where it is known locally as waweyaro. It mainly inhabits humid forests and mangrove swamps, being highly arboreal.
The black tree monitor is primarily insectivorous, consuming mostly insects but also smaller lizards, small mammals such as shrews, scorpions, eggs, and the nestlings of birds. Like other members of the V. prasinus species complex, they are occasionally seen eating plants in captivity, although the gut contents of wild monitors were not reported to contain plant matter.
In captivity, newly hatched members of the V. prasinus species complex often refuse food for more than two weeks, although force feeding may be recommended before then and until they begin feeding by themselves.
Like other monitor lizards, this species is highly intelligent amongst reptiles, and like others of the V. prasinus species complex, demonstrates complex problem solving abilities, fine motor coordination, and skilled forelimb movements when hunting prey. When it cannot reach prey in tight crevices and hole with its jaws, it will instead extract prey by reaching for it with a forelimb and hooking it out with its claws, allowing it to exploit a wider range of niches.
Little is known about the reproduction of V. beccarii in the wild. Some report that this species and the rest of the V. prasinus species complex lay their eggs in arboreal termite nests. The surfaces of such nests would be relatively dry, despite very high relative humidity.
As of 2020, the species V. beccarii is listed as "data deficient" on the IUCN Red List, as insufficient information is available to make reliable population assessments. Deforestation, encroachment by farmland, and the international pet trade are noted as possible current threats.
