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86 IGUANA  •  VOLUME 13, NUMBER 2  •  JUNE 2006 GRISMER

Gliding Lizards in the Genus Draco use wings for “flight” and also to facilitate species recognition and intra-species communication.

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Standing on the peak of Gunung Kajang on Tioman Island
after a miserable, leech-infested, three-day climb to the sum-

mit, I was looking across a deep valley toward the twin peaks of
Nenek-Semukut wishing I could spread my wings, glide
between the peaks across the valley, land on the beach at
Mukut, and crack open a nice, cold drink — anything to keep
from hiking back down that mountain. As it turns out, I’m not
alone. Flying has been a preoccupation of humans for time on
end. Sadly, however, humans will never acquire the capability
of unassisted flight and we’ll have to continue appeasing and
teasing ourselves with everything from hang-gliders to space
shuttles.

In other vertebrates, however, flying is really no big deal.
Some fish leap out of the water to escape predators, extend their
enlarged pectoral fins, and glide for hundreds of meters. Many
frogs have extensively webbed, elongate fingers and toes that
function as parachutes when they leap from the leaves and
branches of trees to glide across the forest. Several groups of
mammals, ranging from bats to rodents to colugos, have
evolved many different ways to move through the air. Reptiles
have been flying for millions of years. The earliest fliers were the
Frigate Bird-like pterosaurs. They were also the first reptiles
capable of powered flight and ranged in size from chickens to
giants having wingspans of over 16 m. However, the most suc-
cessful flying reptiles of all time are (not were) the dinosaurs and
their modern-day representatives — birds.

In southeastern Asia, modern, non-avian reptiles have
gone crazy and flight of some sort has evolved independently at

least three, maybe four times in lizards, and once in snakes —
but why flight, and why in southeastern Asia? Although a num-
ber of hypotheses have been proposed, the overarching theme

The Flying Reptiles of Peninsular Malaysia
L. Lee Grismer

Department of Biology, La Sierra University, Riverside, California, 92515, U.S.A.

Photographs by the author except when otherwise indicated.

IGUANA  •  VOLUME 13, NUMBER 2  •  JUNE 2006 87FLYING REPTILES OF PENINSULAR MALAYSIA

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Black-bearded Gliding Lizards (Draco melanopogon) have light bodies
with big wings and can attain lift immediately after leaving the tree,
even at slow speeds, and are capable of considerable in-flight maneu-
verability.

The Bronzeback Snake (Dendrelaphis cyanochlorus) is an adept climber
that frequently preys on arboreal lizards.

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throughout all of them is predator evasion. Think about it:
You’re less than 15 cm in body length, you have no formidable
defenses, and you’re living in a jungle. By default, that makes
you one of nature’s “fast-food” entrées. So, if you want to avoid
becoming the next McLizard in the Rainforest Happy Meal,
you had better develop an effective escape mechanism.

This always seemed logical to me, but it really hit home
one afternoon while I was taking a break along the banks of the
Sungai Mentawak on Tioman Island. I was just about to
resume my hike when I noticed a Bronzeback Snake
(Dendrelaphis cyanochloris) crawling up the trunk of a large tree.
This snake’s ability to climb on flat, vertical surfaces had always
fascinated me, so I decided to watch for a while. Its coils were
purposely looped in just the precise way necessary for gaining
purchase on the irregularities of the tree’s surface as it contin-
ued to effortlessly push itself upwards. Then I noticed it was
ever so slightly moving its head from side to side and rapidly
flicking its tongue — the telltale signs that it was following a
scent-trail. At that very moment, I saw a Black-bearded Gliding
Lizard (Draco melanopogon) leap from the tree and glide
through the green, filtered light of the forest to land on a dif-
ferent tree. Then, suddenly, the snake struck and grabbed a
Spotted Forest Skink (Lipinia vittigera), which I hadn’t seen,
right off the side of the tree. While the Bronzeback Snake
gnawed and manipulated the Forest Skink in its mouth, to
position it just so before swallowing, I realized that this partic-
ular little skink and I had something in common; we both
wished that we could fly.

What made that crucial life-or-death difference between
the skink and the gliding lizard was a wing. In fact, gliding
lizards (genus Draco) are southeastern Asia’s most adept flying
reptiles, and their wings have clearly contributed to their wide-
spread distribution (India to eastern Indonesia) and radiation
(over 40 species). Oddly enough, the Draco wing is just a mar-
velously rearranged rib cage. The opposing ribs, the ends of
which normally meet in the center of the body to form a bony
basket (i.e., the rib cage) to protect the heart and lungs, have
become disconnected. The ribs have lengthened and now lie
bunched up alongside the body when not flexed. Muscles in the
chest that normally lift and elevate the rib cage to draw air into
the lungs now pull the ribs forward and outward, opening the
wing. The amount of skin along the sides of the body has

increased and now functions as the flying surface that the
lengthened ribs support. Although this wing is not capable of
generating power, it does provide enough lift to extend the
length of the glide and provide considerable in-flight maneu-
verability.

Gliding lizards use their wings for more than just flight,
however. These expansive surfaces also function as prime adver-
tising space for communicating to other gliding lizards. Each of
Malaysia’s 11 species has its own, unique wing pattern.

When not flying or displaying, gliding lizards are com-
monly seen sitting head-up on the trunks of trees with their
wings inconspicuously folded against their bodies. They spend
many of their daylight hours running up and down trees feed-
ing on ants, which make up the vast majority of their diet.
However, when it’s time for a change of scenery, they simply
leap from the tree, extend their ribs to open the wings, and
glide to the next tree. The extent and speed of the glide depends
on a couple of factors: Height of the lizard on the tree and the
surface area of the wing relative to the weight of the body. As it
turns out, not all Draco are created equal. The smaller, frail
Black-bearded Gliding Lizard, with its pencil-neck and light
bulb-shaped head, has a light body with big wings, attains lift
immediately after leaving the tree, even at slow speeds, and is
capable of considerable in-flight maneuverability. In stark con-
trast, the Orange-bearded Gliding Lizard (D. fimbriatus), with

88 IGUANA  •  VOLUME 13, NUMBER 2  •  JUNE 2006 GRISMER

Orange-bearded Gliding Lizards (Draco fimbriatus) have thick necks,
heavy, robust bodies, and relatively small wings; consequently, in-flight
maneuverability is poor, but glide speed is very fast.

Spotted Forest Skinks (Lipinia vittigera) often forage on trunks of
trees, but lack the escape capabilities of gliding lizards.

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IGUANA  •  VOLUME 13, NUMBER 2  •  JUNE 2006 89FLYING REPTILES OF PENINSULAR MALAYSIA

Wing patterns of gliding lizards serve to facilitate species recognition and intra-species communications. Patterns of western Malaysia’s species of
Draco are exceedingly variable. From left to right: (top row) D. blanfordii, D. cristatellus; (upper middle) D. fimbriatus, D. formosus; (lower mid-
dle) D. haematopogon, D. maximus; (bottom row) D. maculatus, D. melanopogon.

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90 IGUANA  •  VOLUME 13, NUMBER 2  •  JUNE 2006 GRISMER

More wing patterns of western Malaysian species of Draco: D. quinque-
fasciatus (top left), D. sumatranus (top right), D. taeniopterus (middle),
and D. melanopogon (bottom; note the variation in the extent of stip-
pling when compared to the individual illustrated in the previous figure).

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its thick neck and heavy, robust body and relatively small wings,
has poor in-flight maneuverability but a very fast glide speed.
In fact, when this species jumps off a tree, it has to dive straight
down with its wings folded against its body until it picks up
enough speed to open them up and glide. When it does glide,
it looks like a jet rocketing through the forest. Consequently,
Orange-bearded Gliding Lizards often are found high in some
of the forest’s tallest trees, from which they can safely dive in
order to gain the momentum necessary to initiate the glide.
Black-bearded Gliding lizards usually are found on lower por-
tions of trees.

As it turns out, this is one of the reasons these two species
can coexist in the same forest and even on the same trees. Their
flight anatomy helps separate them ecologically and keeps them
from competing directly for some of the rainforest’s resources.
In certain areas of the forest, up to eight different species of
Draco may occur together. Generally, when closely related
species with unique, restrictive life histories (and being an arbo-
real, flying, anteater is pretty restrictive) live in the same area,
the potential for competition is high and resources must be
carefully partitioned. Draco do this in such a way that you rarely
see more than two species in close proximity. For example,
Common Gliding Lizards (D. sumatranus) and Spotted Gliding
Lizards (D. maculatus) are common in open and disturbed
areas; Five-banded Gliding Lizards (D. quinquefasciatus) are
usually found in dense forest with relatively small, closely-
spaced trees; Giant Gliding Lizards (D. maximus) are somewhat
restricted to riparian areas; smaller Yellow-bearded Gliding
Lizards (D. haematopogon) and larger Blanford’s Gliding Lizards
(D. blanfordi) occur at higher elevations than most other
species; and Black-bearded Gliding Lizards and the larger
Dusky Gliding Lizards (D. formosus) are habitat generalists in
lowland forests.

However, Gliding Lizards aren’t the only flying, reptilian
denizens of Malaysia’s rainforests. As if geckos weren’t weird
enough already, with their big heads, bulging lidless eyes, abil-
ity to vocalize, and elaborate hands and feet, some can add
flight to their résumés. As exemplified by Flying Geckos (genus
Ptychozoon), their wings lack the elaborate thoracic (chest) mod-
ifications of Gliding Lizards. Instead, they are composed solely
of a large flap of skin along their flanks. These flaps remain
folded across the belly until the lizard jumps from a tree. At that
point, they become passively opened by air during the descent.
Accompanying the body flaps are extended flaps along the sides

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IGUANA  •  VOLUME 13, NUMBER 2  •  JUNE 2006 91FLYING REPTILES OF PENINSULAR MALAYSIA

of the head, neck, and tail, backsides of the hind limbs, and
extensive webbing on the hands and feet. During flight, when
all the flaps and webbing are splayed and extended, they serve
to provide more of a parachuting effect rather than generating
lift as with the wing of a Gilding Lizard. Nonetheless, I have
seen Kuhl’s Flying Gecko (P. kuhli) display remarkable in-flight
maneuverability and actually change directions 180° during
flight.

Very similar flying surfaces have evolved independently in
an unrelated species known as the Frilly Gecko (Cosymbotus
craspedotus). The Frilly Gecko is smaller than most Flying
Geckos and has not been observed demonstrating the same in-
flight maneuverability or ability to glide from tree to tree. It
usually uses its parachuting capabilities to glide from one por-
tion of a tree to a lower section of the same tree in order to
avoid predators.

The different means by which these distantly related
groups of lizards have solved the same problem (making a wing
to escape predators) beg an interesting evolutionary question. I
mean, if you’re a lizard and you’re going to make a wing, why
not do it the same way? Well, it probably has a lot to do with
the general life styles of the members of their respective fami-
lies to whom they are related. In southeastern Asia, the
Agamidae, the family to which Gliding Lizards belong, are
arboreal, diurnal, conspicuous insectivores that signal to one
another by puffing out their throats and expanding their chests
to display their brilliant color patterns. They also jump from
branch to branch in search of prey and to escape predation. So,
in a sense, they can already do everything necessary to fly —
jump from one place to another and expand their rib cages.
Now all that’s necessary is to do them both at the same time
and let natural selection run its course. In support of this
hypothesis is a remarkably obvious intermediate condition in
the Green Crested Lizard (Bronchocela cristatella), a common,
arboreal agamid also native to southeastern Asia. When threat-
ened, Green Crested Lizards will leap from one tree to next,
splay out their limbs, and expand their rib cages during flight.
Although they have no trace of a wing, the increased surface
area resulting from the expanded rib cage and splayed limbs sig-
nificantly decreases the angle of the drop and extends the length
of the “glide.” So, seeing how natural selection may again,
within the same selection regime and same related group of
lizards, be developing flight in the Green Crested Lizard is not
hard to imagine.

Geckos (family Gekkonidae), however, are cryptic species
that attempt to go undetected during the day and are active at
night. All the displaying and leaping common to many agamids

Tail and thigh flaps and webbed foot of a Flying Gecko (Ptychozoon
kuhli).

Nesting female Draco sumatranus.

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do not happen in geckos. In fact, their color patterns generally
match the substrate on which they reside, enabling them to go
unnoticed. Interestingly, the Flat-tailed Gecko (Cosymbotus
platyurus), a species closely related to the Frilly Gecko, presents
us with another example of intermediacy. It has the same folds
of skin along the head, body, limbs, and tail as the Frilly Gecko,
but they’re not nearly as well developed. These geckos lay these
flaps out on the trunk of the tree to prevent the curvature of the
body from casting a shadow where it contacts the trunk in
order not to give away its location. If these flaps passively
opened up like they do in other geckos when this gecko jumps
from one branch to another, and this imparted even a small
advantage by extending the length of the jump, natural selec-
tion will come into play. This is a likely example of what evo-
lutionary biologists refer to as “preadaption” — a situation in
which a structure evolves to be used in one context (camou-
flage) and becomes modified later to be used in a completely
different context (flight).

Because of their lack of limbs and other appendages, one
might think that the most unlikely group of vertebrates to
evolve flight mechanisms would be snakes. However, in penin-
sular Malaysia, three, closely related species of snakes have the
ability to glide for considerable distances. These are the Tree
Snakes (genus Chrysopelea). Their flight modification involves
a simple little notch on each side of each belly (ventral) scale
where the ends turn upwards along the lower sides of the body.
This notch works like an expansion joint, allowing Tree Snakes
to flatten out and widen their bodies. The flat, wide body works
like a parasail, and its undulatory movements during flight,
analogous to a spinning frisbee, stabilize the body to prevent it
from overturning. Prior to launching themselves from branches,
Tree Snakes hang the uncoiled forepart of their body off the

92 IGUANA  •  VOLUME 13, NUMBER 2  •  JUNE 2006 GRISMER

When threatened, Green Crested Lizards (Bronchocela cristatella) will
leap from one tree to the next, splay out their limbs, and expand their
rib cages during flight. Although they have no trace of a wing, the
increased surface area resulting from the expanded rib cage and
splayed limbs extends the length of the “glide.”

Kuhl’s Flying Geckos (Ptychozoon kuhli) display remarkable in-flight maneuverability and can change directions during flight.

Frilly Geckos (Cosymbotus craspedotus) usually use their parachuting
capabilities to glide from one portion of a tree to a lower section of
the same tree in order to avoid predators.

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IGUANA  •  VOLUME 13, NUMBER 2  •  JUNE 2006 93FLYING REPTILES OF PENINSULAR MALAYSIA

branch in a “J-loop.” Then, by rocking the body upward while
simultaneously springing outward by rapidly straightening their
coils and releasing their hold on the branch, the snakes take
flight. Intermediate conditions to this style of flight are found
in related, semi-arboreal snakes such as Bronzebacks (men-
tioned earlier), which have notched ventral scales that help
anchor them to the substrate while climbing vertical surfaces.
They also expand their rib cages as a defense mechanism to
expose brightly colored markings on their scales. So, the three
main ingredients, arboreality, notched ventral scales, and a
behavior involving the expansion of the rib cage, already existed
in this group of related snakes — perhaps another example of
preadaptation.

So, back to the earlier questions of “why flight, and why
here in southeastern Asia?” I think I’ve pretty much answered
“why flight,” so let’s look at “why in southeastern Asia?” With
the exception of birds and bats, when you compare the num-
ber of flying vertebrates in Asian and Australasian rainforests to

those in the world’s other major rainforest ecosystems —
Central and South America and Africa — a striking pattern
emerges. These other rainforests have no flying vertebrates.
Also, no really solid or generally agreed upon hypotheses
explain why. However, the most common explanation suggests
that the presence of flying reptiles has to do with Asian rain-
forests lacking the extensive vines and understory vegetation
that, in the other rainforests, connect adjacent trees to one
another. Additionally, the crowns of some trees in Asian rain-
forests are discontinuous. In fact, in species such as the Kapur
(Dryobanalops aromatica), the crowns of adjacent trees chemi-
cally repel one another. Consequently, getting from one tree to
the next is more difficult for arboreal species unless they climb
down to the ground and walk across the forest floor, running a
substantial risk of becoming prey for some opportunistic pred-
ator — so they fly.

Whatever the reasons behind these remarkable evolution-
ary success stories, I don’t think I will ever become accustomed
to standing in the forest and seeing a snake go gliding by over-
head or a Giant Gliding Lizard with a wingspan like that of a
small pigeon leap from a tree to glide 30–40 meters across a
stream and land on another. In no other rainforests in the world
can we enjoy these natural eccentricities, which leaves me say-
ing to myself once again, “I sure wish I could fly.”

Crowns of adjacent Kapur Trees (Dryobanalops aromatica) chemically
repel one another, resulting in a discontinuous crown.

Tree Snakes (Chrysopelea) flatten out and widen their bodies and can
glide for considerable distances. From top to bottom: C. ornata, C.
paradisi, and C. pelias.

Flat-tailed Geckos (Cosymbotus platyurus), a species closely related to
the Frilly Gecko, use folds of skin along the head, body, limbs, and tail
to prevent the curvature of the body from casting a shadow on a tree
trunk and giving away its location to a predator.

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