A colugo on the side of a tree with part of the patagium showing — In the daytime, colugos are normally nestled into the trees of the forest canopy. © Joshua Davenport/ Shutterstock

Colugos: Expert gliders of the forest

By Katie Spence

Colugos have a very clever mode of transportation that has earned them somewhat of a deceiving nickname. While we sometimes call them flying lemurs, they aren’t lemurs and they technically can’t fly.

Our scientist, Christian Ching, who’s been doing research in the forests of southeast Asia, introduces these mysterious, nocturnal tree-dwellers.

What is a colugo?

Colugos belong to their own unique order, Dermoptera. There are only two species – the Philippine colugo and Sunda colugo.

Philippine colugos live on the southern islands of the Philippines, whilst Sunda colugos are found in a few regions across southeast Asia, from southern Myanmar to Indonesia.

“There are thousands of species of bats and rodents and they’re very diverse,” explains Christian. “There are rodents that burrow, climb trees and scamper along the ground and all bats fly. Colugos, on the other hand, are an order by themselves that are specialist gliders and are only found in southeast Asia.”

An adult colugo clings to a tree as a baby colugo looks down — Colugos are excellent gliders and can transport their babies until they’re old enough to glide on their own. © stefanophotographer/ Shutterstock

At first glance, colugos look like a cross between a bat, a squirrel and a kite. They’re strictly arboreal – meaning they only live in trees – and their soft, mottled reddish or grey fur acts as camouflage, helping them blend into trees. Colugos also have pointed snouts, small ears, and large, forward-facing eyes, which give them excellent vision for their nocturnal lifestyle.

Being nocturnal means that they’re less likely to be competing for food with quicker animals. It also means they can stay out of sight of predators, such as eagles and other carnivores. In the daytime, colugos are typically found nestled high in the canopy, using their sharp claws to grip to the tree bark.

Colugos are the closest living relative to primates – the group that includes lemurs, as well as monkeys and humans.

“Evidence shows that they’re a sister group to primates. They had a common ancestor at one point and then they split off. Long limbs and flexible fingers went to monkeys and apes, whilst the gliding membrane and claws went to colugos,” says Christian.

What is a colugo’s patagium?

One of the colugo’s most important features is its patagium, which is a large membrane of skin. A few other animals have a patagium, such as bats, flying squirrels and even prehistoric pterosaurs. But the structure of a colugo’s patagium is unique. It stretches around their entire body from the neck all the way to the tips of the fingers and tail.

It’s thanks to their patagium that colugos are such excellent gliders.

Colugo holding onto the side of a tree looking down — Colugos are well adapted to their life in the tree canopy, with sharp claws that enable them to cling to the tree bark. © Attapol Yiemsiriwut/ Shutterstock

Colugos have been recorded gliding as far as 150 metres. Gliding between the trees is an extremely energy-efficient way of moving. It also means they can travel and hunt without descending to the dangerous forest floor where they could be attacked by predators.

Their patagium is vital for their survival but due to the tropical environment where they live, it can be prone to developing mould, picking up dirt or housing insects and parasites.

Colugos are one of only a few animals who have evolved toothcombsopens in a new window. This means that some of their teeth are subdivided into fine, comb-like structures which help with grooming and maintaining their patagium.

Can colugos fly?

Unlike birds or bats, colugos can’t fly. Instead, they’re gliding mammals. But what’s the difference between the two?

“Flying is active, meaning that an animal can gain lift and continuously fly, like bats do. Gliding, on the other hand, can only generate a small amount of lift and is more of a controlled fall,” explains Christian.

A colugo mid-flight with the patagium stretched out — The patagium of a colugo stretches all the way from the tips of the fingers to the end of tail. © Lauren Suryanata/ Shutterstock

Colugos are excellent at steering as they glide. Unlike a flying squirrel, whose patagium extends to the border of the hand, a colugo’s patagium extends right in between the fingers and creates a web. This allows them to have a large amount of control in the air.

Christian says, “Colugos are excellent at steering. I’ve seen them jump from thin little coconut trees and fly across around 100 metres, just to land on another trunk only slightly larger than themselves.”

Threats to colugos

Colugos live in the forests of southeast Asia. “They’re completely dependent on forests to survive and they’re extremely sensitive to disturbance,” says Christian.

“My friends and I used to go down a trail in Singapore all the time. We would see something from 10 to 20 colugos in an hour. Within the last six years there’s been quite a lot of construction work within a site nearby and now you’re lucky if you see one.”

“The forest hasn’t changed whatsoever and the tree coverage is still the same, but it’s the disturbance of the nearby construction and the habitat modification that pushes them away quite quickly.”

Colugo hanging from a tree — Colugos rely on forests for their survival but their habitat is threatened. © Butterfly Hunter/ Shutterstock

Colugos are hunted in some areas, but the biggest threat to them is habitat loss.

“Right now, a main concern within the conservation of colugos is that they are dependent on tropical rainforests. But within the world today, the tropical rainforests of southeast Asia are one of the ecosystems which we are losing most quickly,” says Christian.

There are also questions around the actual number of colugo species.

Christian explains, “Evidence has also suggested that the Sunda colugo, which is found in various regions of southeast Asia, might actually be made up of several distinct lineages, possibly even different species. If this is the case, as we watch losses of the Sunda colugo population in whole areas, we might be witnessing the extinction of entire species without even realising it.”

To protect colugos, we need to protect their habitats. To help them, try looking out for and supporting organisations that are actively working on conserving southeast Asia’s vital rainforests.