Chlamydosaurus kingii
The frilled lizard is a tree-dwelling agamid from northern Australia and southern New Guinea. Its famous neck frill is a visual signal used against predators and other frilled lizards.
By An Nguyen · Published · Updated
See the frill open and folded, juvenile camouflage, tree-climbing posture, body proportions, and natural color variation.
Click any photo to view it larger. 9 images available.
Core article
A closer look at habitat, diet, behavior, reproduction, and conservation.
Most photographs catch the frilled lizard at its loudest: mouth open, body raised, and a broad circle of pleated skin spread around its head. The display is real, but it is not the animal's normal posture. For much of the day, a frilled lizard is quiet and difficult to spot, resting vertically on a tree trunk with the frill folded against its neck.
The frill is a visual signal. A field study based on more than 300 hours of observation found two main uses: communication with other frilled lizards and deterrence of predators. Both sexes raise the frill during social encounters and when faced with a possible threat. During the breeding season, males also use partial frill displays, head movements, tail lashes, and forelimb waves when confronting rivals.
This evidence does not support several older explanations for the structure. The frill is not known to function as a gliding surface, food store, or primary temperature-control device. Its effect is visual: a normally narrow lizard can suddenly present a much larger outline, an open mouth, and contrasting colors.
For a closer look at the folding mechanism, display sequence, and field evidence, read why frilled lizards open their frills.
The folded frill lies along the neck and shoulders. Elongated supports connected to the hyoid apparatus hold the thin sheet of skin. When the lizard opens its jaws and moves this apparatus forward, the pleated skin spreads into a broad semicircle on each side of the head.
Color varies across the species' range. The body is usually grey, brown, orange-brown, or nearly black, while the exposed frill may show yellow, orange, red, or dark markings. Northern Territory guidance notes that a large frill can measure about 25 cm across. Adult males are larger and more robust than females, but field measurements found no matching sex difference in frill size relative to body size.
Adults can approach 90-95 cm in total length, although much of that measurement is tail. The tail is roughly twice the length of the body and helps balance the lizard during rapid movement. Curved claws and long toes provide grip on bark.
Frilled lizards occur across tropical northern Australia, from the Kimberley through the Northern Territory to Queensland, and in southern New Guinea. They are associated with open forest, dry woodland, and savanna where trees rise above a grassy or shrubby understory.
They are primarily arboreal. Radio-tracked animals in Kakadu National Park usually rested on branches high in the canopy and descended for short trips on the ground. Activity follows the wet-dry rhythm of northern Australia: feeding, growth, and breeding increase during the wet season, while the lizards become much less conspicuous in cooler, drier months.
Tree cover serves several purposes at once. A trunk is a lookout over ground-dwelling prey, a surface for basking, camouflage, and the nearest escape route when danger appears.
Frilled lizards are carnivores, but insects and other invertebrates make up most of the recorded diet. Rather than searching continuously, they often wait above the ground and watch for movement. A lizard may then descend, run to a prey item, seize it, and return to a tree.
Field studies have recorded caterpillars and swarms of winged ants or termites among their prey. A two-year Kakadu study found harvester termites to be a major part of the local diet in both wet and dry seasons. That result describes one monitored population, not a fixed menu for every frilled lizard. Beetles, spiders, and other invertebrates are also eaten, while vertebrate prey appears to be uncommon.
The familiar two-legged run is more than a last-second escape trick. Researchers observed frilled lizards using bipedal movement during routine foraging trips as well. The long hind limbs drive the body forward while the tail acts as a counterbalance; the forelimbs lift clear of the ground for a short burst.
There is no reliable field measurement supporting a precise top speed, so claims such as 15 mph should be treated cautiously. What is well documented is the sequence: remain inconspicuous when possible, display the frill if challenged, and run toward a tree when retreat is the better option.
Frilled lizards are not venomous. Their display is defensive, but a cornered animal still has sharp claws and teeth and can bite. Wild individuals are best observed without handling.
Breeding is tied to the wet season. In a long-term field study, females produced clutches of 4 to 13 eggs. The eggs are placed in a shallow nest in sun-exposed soil and incubate for about 70 days, with local conditions affecting development.
Frilled lizards have temperature-dependent sex determination: incubation temperature can influence the sex ratio of hatchlings. The young receive no extended parental care. They emerge able to climb, hunt small prey, and perform the same frill display used by adults.
The frilled lizard (Chlamydosaurus kingii) belongs to the Agamidae, the dragon-lizard family that also includes the thorny devil. It is currently the only recognized species in the genus Chlamydosaurus.
Genetic work has identified three strongly differentiated populations across northern Australia. Those populations have not been formally recognized as separate species, so reliable modern databases continue to use Chlamydosaurus kingii for the Australian and New Guinean range.
The IUCN Red List classifies the frilled lizard as Least Concern because it has a broad range and occurs in protected areas as well as some modified habitat. The overall population trend is listed as unknown, so Least Concern should not be read as proof that every local population is stable.
Land clearing, changes to woodland fire patterns, and feral predators can affect habitat quality or survival in parts of the range. Introduced cane toads are another potential local pressure. Monitoring matters most where several of these changes overlap, especially in the Trans-Fly region of New Guinea and intensively altered parts of northern Australia.
The frill is one of several very different reptile display and defense systems. Compare it with the color-changing signals of a chameleon, the dewlap and head-bob displays of an iguana, and the vocal territorial behavior of a tokay gecko. These animals share some ecological problems without using the same anatomical solution.
Kingdom
Animalia
Phylum
Chordata
Class
Reptilia
Order
Squamata
Family
Agamidae
Genus
Chlamydosaurus
Species
C. kingii
Field studies show that the frill is primarily a signal for other frilled lizards and a deterrent to predators.
Frilled lizards also run on two legs during routine foraging, not only while escaping danger.
The frill can measure about 25 cm across, roughly the width of a dinner plate.
Males grow larger than females, but the frill is not proportionally larger in males.
These sit-and-wait hunters descend from trees to seize caterpillars and swarming winged ants or termites.
The long tail makes up roughly two-thirds of an adult frilled lizard's total length.
Select a question to reveal the answer.
The frilled lizard (*Chlamydosaurus kingii*) is a large, mostly tree-dwelling member of the agamid or dragon-lizard family. It is the only recognized species in its genus.
Frilled lizards occur across tropical northern Australia and southern New Guinea. They favor open woodland and savanna with trees for perching, shelter, and escape.
They eat a wide range of invertebrates. Field studies record caterpillars, ants, termites, beetles, and spiders, while vertebrate prey is taken only rarely.
They erect the frill during encounters with predators and other frilled lizards. More than 300 hours of field observation found that its main roles are predator deterrence and communication, not thermoregulation or gliding.
Yes. They use short bouts of bipedal running while escaping and during normal foraging trips from a tree to prey on the ground.
They are not venomous and usually rely on camouflage, their frill display, and escape. A cornered or handled animal can still bite or scratch, so wild frilled lizards should be watched without touching.
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