Photo: Lace monitor at WLT sanctuary Ringtail Creek Sanctuary - Angela and Bruce Anderson 

This article featured in Wildlife Lands Issue 21

Apex predators in Australia come in an unusual range of shapes and sizes - dingoes patrol the grasslands, eagles the sky and sharks roam its surrounding seas. But one of the most successful and ubiquitous predators is the often-overlooked monitors, or goannas - some of the largest lizards in the world.

There are 25 species of monitor lizard in Australia, found everywhere except Tasmania. Being almost entirely carnivorous, these lizards are robust with curved teeth and strong claws. Their diet often consists of mammals, birds, insects and other reptiles, and some larger species are reported to hunt kangaroos. They are also avid scavengers, and are often seen feeding on carcasses of livestock and wildlife.

Their fierce appearance and behaviour has made them a prominent figure in Indigenous culture, where they are represented in stories and art and valued as a food source. They are widespread throughout Australia, and are skilled hunters, climbers, swimmers and burrowers.

Monitors are Australia’s biggest lizards: the largest species, the perentie, can grow to up to two metres long. Commonly dark brown, grey or green, they are often marked with pale bands or spots for camouflage. Their sharp claws and teeth aren’t their only weapons – monitors will swing their heavy tails for self-defence, and their saliva may have venomous properties. They will also puff up their neck folds or rear up on their hind legs to appear bigger. Despite this they prefer to avoid a fight, and will usually make a dash for the nearest tree if they think they’re in danger.

But even the most successful predators struggle to survive in the face of development: as forests and grasslands are cleared for agriculture and urbanisation, remnant patches of habitat become more and more fragmented. Small territories make hunting far more difficult, and the removal of termite mounds, logs and leaf litter makes the search for nesting sites increasingly difficult. Young monitors face new threats from predators like dogs, cats and foxes, and larger species are susceptible to poisoning from eating invasive cane toads. 

Over 130 Wildlife Land Trust sanctuaries are home to monitor species, including lace, Rosenberg’s, black-headed and Gould’s monitors. These sanctuaries provide vital habitat for these lizards to nest, hunt and roam. In return monitors play an important role in the ecosystem: keeping small animal populations in check, cleaning up carrion and regulating populations of cats, rabbits and foxes. Wildlife-friendly sanctuaries are vital for monitors, as retaining shelters and nesting areas, fencing off stock and connecting significant habitats plays a huge role in allowing these awe-inspiring reptiles to thrive.