Frilled Lizard — facts, diet, habitat & conservation

The frilled lizard is one of the great bluffers of the animal world. Confronted, it transforms in an instant from a drab tree-hugging lizard into a hissing, gaping monster with a cape of skin flared around its head — and if the act does not work, it turns and runs away on two legs.

Overview

Frilled lizards live in the tropical savanna woodlands and dry forests of northern Australia and southern New Guinea, a landscape of scattered eucalypts and a sharp wet–dry seasonal cycle. They are arboreal, spending most of their lives clinging to tree trunks and branches, and their brown, grey, and orange mottling makes them extremely hard to see against bark. They are diurnal ambush hunters, dropping to the ground to grab passing insects.

The frill

The lizard’s collar is a flap of skin supported by long, jointed rods of cartilage that connect to the hyoid bones of the throat and, crucially, to the jaw. Because of that linkage, when the lizard opens its mouth wide the frill automatically springs open into a disc up to 30 centimetres across, brightly coloured on the inside and around the mouth.

The display is a threat bluff. Facing a snake, bird of prey, dingo, or quoll, the lizard rears up, spreads the frill, gapes to show the vivid mouth, hisses loudly, and jumps forward while lashing its tail — projecting the image of something far bigger and more dangerous. If the predator is not deterred, the lizard folds everything away and sprints for a tree on its hind legs.

Seasonal life

The frilled lizard’s year is split by the monsoon. In the wet season it is active, feeding heavily on the flush of insects — especially cicadas and beetles — putting on fat, and breeding. In the long dry season it becomes almost dormant, sitting motionless high in a tree, eating little, and living off reserves until the rains return. Bushfires, which sweep through this habitat regularly, are a hazard, and the lizards mostly ride them out in the canopy.

Reproduction

Males compete for territory and mates with frill displays and head-bobbing, escalating to biting and wrestling. Females lay a clutch of around 8 to 20 eggs in a shallow burrow dug in sunny, sandy soil early in the wet season. As in many reptiles, incubation temperature influences the sex of the hatchlings, which emerge after two to three months already able to run and flare a miniature frill.

Status

The frilled lizard is listed as Least Concern and remains common across northern Australia. The main pressures are changed fire regimes, habitat clearing at the edges of its range, predation by feral cats, and the toxic cane toad, which frilled lizards may attack and be poisoned by. It is also collected for the international pet trade, where it is prized for its dramatic display.

Frilled Lizard: common questions

What is the frill actually for?

Mainly bluff. When a predator gets too close, the lizard whirls to face it, gapes its bright yellow-and-pink mouth, and snaps the frill wide open — the jaw and frill are mechanically linked, so opening the mouth spreads the collar — making the animal look several times bigger and more dangerous than it is. It hisses, lunges, and lashes with its tail. If that fails it drops the display and bolts. The frill also helps with temperature control, catching sun to warm up or being spread to shed heat, and males use it in courtship and territorial displays.

Do frilled lizards really run on two legs?

Yes. When fleeing, a frilled lizard rears up and runs bipedally, its long tail held out as a counterbalance and its frill folded flat against the neck, heading for the nearest tree. It is one of the more committed bipedal runners among lizards, and the sight of one sprinting upright across open ground is striking. Once on a trunk it scrambles around to the far side, out of view.

Where do frilled lizards spend their time?

Up trees. Frilled lizards are strongly arboreal, clinging head-up to vertical trunks and branches where their mottled brown-grey colouring makes them nearly invisible against the bark. They descend to the ground to catch prey, move between trees, and, in the case of males, patrol territory, then climb straight back up. Through the long tropical dry season they become almost completely inactive, perched high in a tree living off body reserves.

Is the frilled lizard the one from Jurassic Park?

The dinosaur Dilophosaurus in the film was given a frill and venom-spitting ability inspired partly by the frilled lizard, but that was invention — the real Dilophosaurus had no frill and there is no evidence it spat venom. The frilled lizard itself is harmless to humans — no venom, and a bite that is startling but minor.