Colugos are aboreal gliding mammals found in South-east Asia. Formerly known as flying lemurs, there are just two species in a single genus, which makes up the entire family Cynocephalidae and order Dermoptera. Although they are the most capable of all mammal gliders, they cannot actually fly, and they are not lemurs.
Colugos are fairly large for a tree-dwelling mammal: at about 35 to 40 cm in length and 1 or 2 kilograms in weight, they are comparable to a medium-sized possum or a very large squirrel. They have moderately long, slender limbs of equal length front and rear, a medium-length tail, and a relatively light build. The head is small, with large, front-focussed eyes for excellent binocular vision, and small, rounded ears.
Their most distinctive feature, however, is the membrane of skin that extends between their limbs and gives them the ability to glide long distances between trees. Of all the gliding mammals, the colugos have the most extensive adaptation to flight. Their gliding membrane, or patagium, is as large as is geometrically possible: it runs from the shoulder blades to the fore-paw, from the tip of the rear-most finger to the tip of the toes, and from the hind legs to the tip of the tail; even the spaces between the fingers and toes are webbed to increase the total surface area.
They are surprisingly clumsy climbers. Lacking opposable thumbs and not being especially strong, they proceed upwards in a series of slow hops, gripping onto the bark of trees with their small, sharp claws. They are as comfortable hanging underneath a branch as sitting on top of it. In the air, however, they are very capable, and can volplane as far as 70 metres from one tree to another with minimal loss of height.
Colugos are shy, nocturnal, and restricted to the tropical rainforests of Southeast Asia. In consequence, remarkably little is known about their habits. They are certainly herbivores, and are thought to eat mostly leaves, shoots, flowers and sap, and probably fruit as well. They have well-developed stomachs capable of extracting nutriment from leaves.
There are two species, the Malayan Colugo being the larger and more common of the two.
Although they are placental mamals, colugos are almost marsupial-like in their breeding habits. The young are born after just 60 days of gestation in a tiny and undeveloped form, and spend their first six months or so of life clinging to the mother's belly. To protect them and transport them she curls her tail up to fold the gliding membrane into a warm, secure quasi-pouch. Breeding is fairly slow as the young do not reach full size until they are two or three years old.