Australian Geographic – July-August 2019

July. August 43

Between the 1880s and 1930s, various naturalists proposed

not only that the frill might be used for warming and cooling,

or gliding down from trees, but also for food storage, amplify-

ing distant sounds or attracting mates. Rick showed that two

common theories, relating to predator deterrence and social

interaction, did appear to hold true. He found that adult males

were heavier, had proportionately larger frills than females and

displayed more often than females and juvenile males. It sug-

gested the frill played a role in competition between males by

warning rivals off from entering a male’s territory, which is

roughly 2ha.

Frillies are agamids – members of family Agamidae, which

are commonly known as dragons. These typically have complex

social interactions, communicating with each other using behav-

iours such as head-nods, arm-waves and push-ups. They tend

to pick elevated sites to display to each other. “The frilly has

just taken that to a whole other level,” Rick says. “They’re one

extreme of a very persistent theme within the dragons, which

is that they’re very territorial and use vision to communicate.”

In Kakadu, at least, frillnecks prefer open woodland with

small trees, where they can perch on a branch a metre or so

from the ground. “A male can sit on his tree and, if he starts

slapping his tail and doing push-ups and f lapping the frill,

it’s visible for a prolonged distance to another male who’s got

terrific eyesight,” Rick says.

T

HE COLOUR OF the lizard’s frill is another topic that

has interested researchers. “It has been known for some

time that there’s variation in frill colour across their

range, going from red in the west, grading from orange in the

NT, and yellow in northern Queensland and New Guinea,

to whiter in southern Queensland,” says Dr Mitzy Pepper,

who studies evolutionary relationships among reptiles at the

Australian National University, in Canberra.

Mitzy led a team that looked at the DNA of 83 frillnecks

from across the species’ range to see if colour differences were

COMMON NAME

There is no generally agreed upon common

name. Among those widely used are frillneck

lizard, frilled lizard, frilled dragon and

frill-necked lizard – all of which are often

shortened to frillie. The species is known

as the bemmung to the Gagadju people

of the Kakadu region.

SCIENTIFIC NAME

Chlamydosaurus kingii

(King’s cloaked lizard)

WEIGHT

Typically 500–750g, but the

heaviest individual Christian

has caught weighed 840g.

LENGTH

70–95cm, including tail

BREEDING

Mating takes place in September.

Females lay clutches of 8–20 eggs in

November and hatchlings emerge about

February; the temperature at which eggs are

incubated determines the hatchlings’ gender.

DIET

Mostly insects and other invertebrates;

occasionally small vertebrates

ABORIGINAL RECORD

Gurndamen, the frillneck lizard, is a

Dreaming figure of the Gunwinku people

of Gunbalanja (Oenpelli) in north-western

Arnhem Land.

Frilly facts

This tiny hatchling is yet to develop the full

frill or colouration seen in adult frillnecks.

“It’s the largest and most

dramatic display structure

seen in any reptile.”

Frillnecks are large lizards,

adults o‘en growing longer

than 80cm, including the tail.

The frill is carried flat, as this

one is, until needed.

Frillneck

distribution

PHOTO CREDITS, FROM TOP LEFT: COURTESY AUSTRALIAN REPTILE PARK; HENRY COOK/GETTY