The draco lizard is a flying lizard of Southeast Asian rainforests that does not have wings. What this animal has is an extraordinary modification of its own skeleton. Five to seven elongated ribs extend outward from the body and are connected by a thin membrane of skin, forming a pair of gliding surfaces that fold flat against the body when not in use and spread wide for flight. It does not flap. It launches from a tree trunk, spreads its ribs, and glides up to 9 meters to the next tree, losing very little altitude in the process.
The gliding surfaces of males are brightly colored, orange and yellow with black markings, and are used in territorial displays as well as for travel. A male Draco defending his territory spreads his gliding membranes to signal to rivals and potential mates, the same structures serving two completely different functions depending on context. The female’s membranes are blue and are used less frequently for display.
How the Draco Lizard Glides
What strikes me about this species is how completely the solution departs from anything else evolution has produced for gliding. Flying squirrels use skin between their limbs. Colugos use a membrane that extends from neck to tail. The lizard uses its ribs, extended outward like the spokes of an umbrella, a structural solution that no other vertebrate has arrived at independently.
Its entire life is vertical. This small lizard feeds on ants and termites on tree trunks, defends a territory of several trees, and descends to the ground only to lay eggs, burying a small clutch in the soil and returning to the canopy within minutes. The ground is dangerous. The trees are home. The ribs are the bridge between them.
The Forest the Draco Lizard Needs
Draco lizards are inseparable from tall, closed-canopy forest with trees spaced close enough to glide between, making them true specialists of intact rainforest. Logged or fragmented forest, where the canopy is broken and trees are widely spaced, eliminates the gliding corridors they depend on. Deforestation across Southeast Asia has reduced their habitat significantly, and while the species is not currently listed as threatened, the forest it needs is disappearing at a rate that makes complacency unwarranted.