The Yellow-spotted monitor (Varanus panoptes) is a monitor lizard found in Australia and southern New Guinea. It's the third largest lizard in Australia, after perentie and Lace monitor. It is also known as the Argus monitor and may be referred to as the Floodplains goanna in the northern regions of Australia.
The Yellow-spotted monitor somewhat resembles the widespread Sand goanna (Varanus gouldii). Large, dark spots appear in rows along its back, becoming especially distinct at the center of the back where they are interspersed with smaller and paler spots. Bands of color occur toward the tip of the tail. Most individuals are yellow in color, with a background of brown or dark tan, but their color often varies on an individual basis or on their place of origin.
Yellow-spotted monitors occur in northern and western regions of Australia and southern New Guinea. They live in a large variety of biomes and habitats including savanna, woodlands, coastal regions, mangrove fringes, and urban areas. Yellow-spotted monitors favor riparian areas and are often found around a permanent source of water.
Yellow-spotted monitors are primarily terrestrial and spend a great deal of time on the ground. They are avid diggers and will dig large burrows or take over an already existing burrow, where they spend a sizable portion of their time. Despite this, they will eagerly forage in trees and in the water. These large lizards are quite fast and will run up to 100 meters away to the nearest tree or burrow when they are chased. They often "tripod", raising up on their hind legs and supporting themselves with their tail. This unusual behavior is used to spot potential prey or enemies from a distance or when they are threatened. This habit provides them a unique characteristic that separates them from most other monitors. Yellow-spotted monitors hunt for prey by keying in on the movement, chasing it down, and overpowering it. They have great senses, with smell being the most acute. Like all monitors, they have forked tongues and a vomeronasal organ in the roof of their mouths. They use this organ in the same manner as snakes and other varanids do and can often be seen flicking their tongues in search of a meal.
Yellow-spotted monitors are carnivores and prey on almost anything that they can overpower. Their diet includes fish, crabs, small birds, rodents, insects, and even other monitors.
In Arnhem Land (the Northern Territory of Australia), female Yellow-spotted monitors lay 6 to 13 eggs between January and February. The young of this species are known to reach reproductive maturity at the age of 2 years.
Recent studies suggest that the infestation of Cane toads, a novel and toxic species, has severely damaged the population of the Yellow-spotted monitor within the Top End (the Northern Territory of Australia). It is estimated that numbers have dropped by as much as 90% in many areas.
The IUCN Red List and other sources don’t provide the number of the Yellow-spotted monitor total population size. Currently, this species is classified as Least Concern (LC) on the IUCN Red List but its numbers today are decreasing.
