COLUGO (FLYING LEMURS): CHARACTERISTICS, SPECIES, BEHAVIOR

COLUGOS

gliding colugo

Colugo look like crosses between a bat and flying squirrel. They are sometimes called "flying lemurs" but they are not lemurs, and they do not fly. They are arboreal, nocturnal, leaf-eating, gliding mammals that inhabit rain forests of Southeast Asia and the Philippines. They are not closely related to the true lemurs of Madagascar but make up its unique order: Dermoptera, or “skin wings.” They have the most extensive flight membranes of any mammalian glider, stretching from its head its tail and embracing all four limbs. In flight they look like kites. Mothers almost always fly with their babies with them. By contrast squirrel mother usually leave their young behind in a tree cavity.

Colugos are superb glider, arguably the best among mammals. They can travel as far as 70 meters (230 feet) from tree to tree without losing much altitude. One with a Sunda flying lemur observed traveling about 150 meter (490 feet). In contrast colugos are not very good climbers. They lack opposable thumbs and move up trees in a series of slow hops, gripping onto the bark with their small, sharp claws. [Source: Wikipedia]

David Attenborough wrote: The colugo "is about the size of a cat. Its gliding membrane stretches not from wrists to ankles, but to the tips of both fingers and toes, half way up the neck and to the very end of its tail. With the help of this, it can cover 70 yards in a single graceful and silent glide. It is. From all accounts, exclusively vegetarian. The fur on the upper side of its membrane is particularly handsome, dappled with cream or brown blotches each ringed with black that conceal it very effectively as it nestles in the center of palm trees or hangs below a branch with all its feet placed close together. Its floppy gliding membranes is so big, and its slender legs so extremely adapted to serve as lightweight struts for that membrane, that on the ground it is virtually helpless.

“But what kind of animal is it? Its teeth, that in most mammals normally provide valuable clues in establishing affiliations, are of no help for they are quite unlike those of any other living creature. The incisors of the top jaw are placed at the sides leaving a gap at the front ad the second of them has, uniquely among mammals, two roots. The incisors on the lower jaw are even stranger. They project not up but forward and are toothed like combs, Whether the colugo uses these to groom itself or to help it feed in some way is still not known. But although no living animal has teeth that are comparable, fossil skulls with very similar detrition are not uncommon in shales and sandstones laid down some 60-77 million years ago in North America. It seems that the colugo is the last living representative of a very ancient and successful; group that appeared just as mammals were beginning their expansion.

Colugo Characteristics and Anatomy

Colugos (Dermoptera) are strange animals that weigh one to two kilograms and are about the size of a very large squirrel and possess a large, well-furred membrane extending from the sides of their neck to the forepaws, and from the forepaws back to the hind feet and end of the tail. Phil Myers wrote in Animal Diversity Web: This membrane allows them to glide long distances (over 100 meters) with considerable manueverability. The membrane is covered by brownish or gray fur with irregular white spots. The fore and hind feet have long, needle-sharp claws, useful for holding onto bark and branches.

Skeleton of Philippine flying lemur

The skull of a colugo is very distinctive, broad and flat in outline and with a nearly complete postorbital process that sets off the eye sockets. The tympanic bullae are flattened, and the palate is broad and flat. The teeth are relatively small and simple. The molars retain the basic tribosphenic pattern, with well developed lophs used in chewing abrasive plant matter. The first upper incisor is reduced, while the second (outer) upper incisor is caniniform. The lower incisors form a comb-like structure that is thought to be used both in grooming and in feeding. [Source: Phil Myers, Animal Diversity Web (ADW) /=]

Colugos are sometimes called "flying lemurs," because of their habit of gliding and the fact that their faces are lemur-like. They are not lemurs, however, and they have not achieved real flight (among mammals only bats have attained that distinction). The order Dermoptera contains a single family, the Cynocephalidae, which is made up of a single genus (Cynocephalus) with two species. Colugos are found in southeastern Asia, including the southern Philippines. /=\

Colugos are herbivorous, feeding on fruit, young leaves, and flowers. They scrape green material from the surface of leaves with their lower incisors, using their tongue, which is very large, and incisors to pick the leaves. Like many other herbivores, they have a greatly elongated intestine and a very large cecum. The cecum, a sac located at the junction of large and small intestines, is divided into compartments, which harbor microorganisms that break down indigestible cellulose into components that the animal can assimilate. Colugos are nocturnal (active at night), passing the day in dens in hollow trees or suspended from branches. They hang upside down while feeding and travelling along branches. /=\

Colugos are difficult to breed and sustain in captivity and partly because of this relatively few formal studies have been conducted on them. Little information exist on the lifespan; the oldest known captive flying lemur lived to be 17.5 years old.

Colugos — Pre-Bat Living Fossil?

Brian J. Stafford of the National Museum of Natural History wrote in the Washington Post: Members of the order Dermoptera share many anatomical similarities with bats and often have been interpreted to represent a pre-flapping, gliding stage in the evolution of powered flight in bats. For example, the bat wing consists of skin stretched across extensively remodeled hands with very long fingers. Dermopterans also have part of the wing stretching between fingers of the hands, which also are highly modified and have long fingers. [Source: Brian J. Stafford, NMNH, Washington Post November 11, 1998]

However, flying lemurs are neither ancestral bats nor living fossils in the strict sense; they have been evolving along their own evolutionary path for at least 50 million years. Nevertheless, dermopterans may retain anatomical characteristics present in the last common bat-dermopteran ancestor, which probably was nocturnal and had a gliding membrane that stretched between arms, legs and body. It probably had other membranes that stretched between the fingers, between the arms and the shoulder or neck and between the hind limbs to enclose the tail, but not the toes.

ranges of the Sunda flying lemur (red) and Philippine flying lemur (green)

These characteristics are present in living bats and dermopterans. When this ancestral animal glided, it probably used its hands to help control the glide and to maintain stability. Experts have noted that proper orientation of the wing tips in gliding mammals may help to reduce drag, allowing the animal to glide longer distances. Increasing the surface area of the hand-wing would further enhance control and maneuverability and, if co-opted to produce thrust, could have preceded the attainment of powered flight in bats. This particular anatomical complex may have remained unchanged in living dermopterans because it performs an important role in controlling and stabilizing glide.

Other biological systems may have undergone dramatic changes. For example, gliding provides an efficient and rapid means of travel between food sources. However, powered flight is even more rapid. Therefore, ancestral dermopterans may have found themselves outmaneuvered by early bats and so obliged to specialize on an unexploited, but low-quality, food source — young leaves. One adaptive strategy for that kind of diet is to reduce activity and energy expenditure. Dermopterans rarely move around, and they do it slowly. They also have a digestive tract highly specialized for digesting plant material.

Colugo DNA Suggest Belong a Primate Sister Group

In August 2016, in a study published in the journal Science Advances, an international team of researchers announced that had found genetic evidence that suggests that colugos are part of a primate sister group. The team obtained tissue samples from the gliding mammals, performed genetic testing on them and found an interesting relationship between them and primates. [Source: Bob Yirka, Phys.org, August 15, 2016]

Bob Yirka wrote in Phys.org: Scientists and casual observers alike have debated for some time the family tree of colugos — many have suggested they are most closely related to tree shews due to a physical resemblance. They look a lot like bats and because they live in the treetops in remote parts of Asia they have been notoriously difficult to study—making things even more difficult is their failure to survive for long in captivity. In the 2016 study researchers sought to solve the question of their ancestry by conducting a DNA analysis on an available tissue sample from a specimen from West Java.

Their analysis consisted of using illumine instruments to sequence DNA from the sample which they used to create a genome assembly. In so doing they were able to identify 23,081 protein-coding genes which they then promptly compared to sequences made of other 21 mammals. They report that their analysis revealed colugos split off from other mammals approximately 80 million years ago and that the comparisons uncovered a relationship close enough to primates to call them a sister group. The team also tested tissue from a variety of colugo museum samples and in so doing discovered that there are far more species of colugos than anyone had imagined, from as few as 7 to perhaps 14.

The findings by the team are expected to contribute to a growing base of information related to the evolution of the earliest primates and may also help better understand the genetic origins of some modern human maladies—they found signs of positive selection in the colugos, for example, that if present in other mammals, may have led to night blindness and retinal degeneration.

Sunda Flying Lemurs

Sunda flying lemur

Sunda flying lemurs (Galeopterus variegates) are also known as Malayan flying lemurs and Malayan colugos as they inhabit both Malaysia and the Malay Peninsula. Native to tropical rainforests, they spend most of their time in trees but have adapted to a wide variety of environments, including disturbed forests edges, secondary forest, rubber and coconut plantations, gardens, fruit orchards, mangrove swamps, tree plantations, highlands and mountainous areas. [Source: Katrina Beatson, Animal Diversity Web (ADW) /=\, Wikipedia]

Sunda flying lemurs are widely distributed throughout Southeast Asia. They are found northern Laos, Cambodia, Vietnam, Thailand, Peninsular Malaysia, Sabah and Sarawak in Malaysian Borneo, Singapore, Brunei, Kalimantan, Sumatra, Bali, Java in Indonesia and many adjacent islands.

Sunda flying lemurs are herbivores (primarily eat plants or plants parts) and are also recognized as folivores (eat leaves) and frugivores (eat fruit). Among the plant foods they eat are leaves, fruit nectar, flowers, sap and other plant fluids, soft plant parts and young leaves. Their unusually comb-shaped lower incisors are thought to be used to scrape sap from trees or to strain fruits and flowers. /=\

Sunda flying lemurs are not endangered. The International Union for Conservation of Nature (IUCN) Red List classifies them as a species of “Least Concern”. In CITES (Convention on International Trade in Endangered Species of Wild) they have no special status.Although Sunda flying lemurs are fairly adaptive animals, their numbers have declined as a result of habitat loss, deforestation, logging and the conversion of forests into farm land. They lemurs sometimes hunted for their meat and skin. In somes places they are regarded as crop pests. It is not clear what their natural predators are. When threatened, they either freeze or climb higher into the trees. Patches of fur are said to resemble lichen. And they can always glide away to make a quick escape.

Sunda Flying Lemur Characteristics

Sunda flying lemurs range in weight from 0.9 to two kilograms (2 to 4.4 pounds) and range in length from 50.5 to 69 centimeters (19.9 to 27.2 inches). Their head and body length ranges from 33 to 42 centimeters (13 to 17 inches) and they have a 17.5 to 27 centimeter (7.1 to 10.6 inch) tails Their average wingspan is 70 centimeters (27.56 inches). Sexual Dimorphism (differences between males and females) is not present: Both sexes are roughly equal in size and look similar. [Source: Katrina Beatson, Animal Diversity Web (ADW) /=]

Sunda flying lemurs have small heads, large and forward-facing eyes, wide brows, and small ears. Katrina Beatson wrote in Animal Diversity Web: They have blunt snouts, and there are no obvious whiskers on their faces. The fur of Sunda flying lemurs is dense and mottled. While the underside is pale, the dorsal fur can be white, gray, black, or red. Unlike Philippine flying lemurs, Sunda flying lemurs have bold patches of color that look similar to lichen on a tree, which aid in camouflage. While Sunda flying lemurs cannot fly, a membrane of skin called a patagium allows them to glide. This membrane is fully furred, extending along the limbs from the neck to the fingers, toes and tail. When gliding, the patagium can extend to about 70 centimeters with the help of an extensor muscle in the flank membrane. Sunda flying lemurs have four legs of similar size with webbed feet and curled claws. Their digits are flattened, and the soles of the feet can form sucking discs to allow a better grip while climbing. /=\

Sunda flying lemurs have 34 carnivore-like teeth. Flying lemurs of the family Cynocephalidae have unique comb-shaped bottom incisors, which can be used for straining or grooming. These incisors include up to up to 20 prongs per tooth. While most incisors of mammals are single rooted, the second incisors of Sunda flying lemurs are double rooted. The front of the top jaw is toothless as the upper incisors are positioned at the sides of the jaw. The canines of Sunda flying lemurs resemble pre-molars. /=\

Sunda Flying Lemur Behavior and Reproduction

Sunda flying lemurs are arboreal (live mainly in trees), scansorial (able to or good at climbing), have the ability to glide, nocturnal (active at night), motile (move around as opposed to being stationary) and territorial (defend an area within the home range). They communicate with sound and sense using vision, touch, sound and chemicals usually detected with smell. Not much is known regarding their home ranges although they do broadly overlap. In the protected forests of Singapore, one Sunda flying lemur had a home range estimated at two hectares. [Source: Katrina Beatson, Animal Diversity Web (ADW) /=]

Philippine flying lemur

Sunda flying lemurs are largely solitary animals but have been observed in small, loosely connected groups and can be territorial of sleeping and foraging areas. They spend most of the day resting in a hole high up the canopy. At night they forage in the trees — gliding when they get to another foraging tree or to find possible mates and protect territory. Sunda flying lemurs are able to glide over 100 meters with little loss in elevation but are quite helpless on the forest floor and are almost never seen there. On trees they grasp the underside of branches or the trunk with all four feet. Climbing trees involves stretching out the two front legs then bringing up the two back legs in kind of an awkward hop.

Little is known about the mating and reproductive behaviors of Sunda flying lemurs. They engage in year-round breeding. The number of offspring ranges from one to two, with the average number of offspring being one. The average gestation period is 60 days. The average weaning age is six months and the average time to independence is three years.

Sunda flying lemurs are altricial. This means that young are born relatively underdeveloped and are unable to feed or care for themselves or move independently for a period of time after birth. Newborsn weighs around 35 grams. Weaning occurs at six months of age, and adulthood is reached at about three years. The mother can mate again shortly after giving birth, and it is possible for a female to be pregnant while still nursing. /=\

Parental care is provided by females. Offspring nurse from a single pair of mammae located near the mother's armpits. The mother can fold her patagium (membrane between the forelimbs and hindlimbs used for gliding) into a pouch to protect and warm her offspring. Young Sunda flying lemurs are dependent on the mother until they are weaned. Offspring cling to the underside of the mother, if not in the pouch, even when she is gliding from tree to tree.

Philippine Flying Lemurs

Philippine flying lemurs (Cynocephalus volans) are also known as Philippine colugos. Thet are found on the Philippine islands of Mindanao, Basilan, Samar, Leyte and Bohol. They are entirely arboreal and in rain forests but are also often seen near coconut and rubber plantations. [Source: Michael Kuo, Animal Diversity Web (ADW) /=]

Philippine flying lemurs eat leaves, fruit, sap, buds, and flowers from a variety of tree species. They hey prefer young leaves, which higher nutritional value than old leaves, and favor larger trees for foraging because larger trees produce more young leaves and other food sources. When feeding Philippine flying lemurs use their enlarged tongue and specialized lower incisors to pick leaves. Their stomachs are oriented towards ingesting large quantities of leafy vegetation. The intestines are convoluted and can approach four meters in length. The pyloric digestive region, the part near the exit to the intestines, is enlarged and divided into compartments. These chambers harbors microorganisms that help break down cellulose and other relatively indigestible carbohydrates.

Philippine flying lemurs are not endangered but they are threatened by deforestation and loss of habitat. The International Union for Conservation of Nature (IUCN) Red List classifies them as a species of “Least Concern”.US Federal List classifies them as Threatened. Philippine flying lemurs are sometimes hunted for meat. They are considered by plantation owners to be crop pests. fruits, leaves, and flowers. /=\

Philippine Flying Lemur Characteristics and Behavior

Philippine flying lemurs range in weight from one to 1.75 kilograms (2.20 to 3.85 pounds). They a little smaller and have darker and less spotted fur than the Sunda flying lemurs, the other colugo species. Both huge eyes and faces that resemble those of fruit bats. Sexual Dimorphism (differences between males and females) is not present: Both sexes are roughly equal in size and look similar.

According to Animal Diversity Web: The head is broad, somewhat like a greyhound's in appearance, with rounded short ears and a blunt muzzle. The limbs are of equal length, with strong sharp claws for climbing, and the toes are connected by webs of skin. This web of skin extends into a distinct structure called a patagium, which stretches from the side of the animal's neck to the tips of the fingers and toes and continues to the very tip of the tail. No other gliding mammal has such an extensive membrane.

The arrangement of the unusual and distinctive incisor teeth is similar to that of herbivorous mammals such as cattle or deer. The upper incisors are located on the sides of the jaw and are caniniform, leaving a gap at the front so they do not oppose the forwardly protruded lower incisors. The lower incisors are comb-like with as many as 20 comb tines arising from one root, which may allow scraping and straining food, and also grooming and cleaning the fur. The molars retain a three-cusped insectivores (mainly eat insects), pattern and have a shearing action that includes a large transverse component. This action, and the crenulated enamel of the molars, provide for efficient mastication of plant material. The dental formula is 2/3, 1/1, 2/2, 3/3 = 34. /=\

Philippine flying lemurs are crepuscular (active at dawn and dusk) and seek refuge during the day in holes in trees. Their foraging activities are highest before sunset and a few hours prior to sunrise. They glide from tree to tree by climbing to the top of a tree and then launching themselves into the air. They are in control of their glides, usually landing on the lower trunk of another tree and then climbing up to start another gliding cycle. To move up a tree, they grasp the trunk with their outspread limbs and move both front feet together, then both hind feet. The glide distances can easily reach over 100 meters. /=\

The average gestation period is 105 days. Usually a single young is produced, but occasionally twins are born. Newborns are relatively underdeveloped. Young are carried on the belly of the mothers even when they are gliding. /=\

Image Sources: Wikimedia Commons

Text Sources: Animal Diversity Web animaldiversity.org ; National Geographic, Live Science, Natural History magazine, David Attenborough books, New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Discover magazine, The New Yorker, Time, BBC, CNN, Reuters, Associated Press, AFP, Lonely Planet Guides, Wikipedia, The Guardian, Top Secret Animal Attack Files website and various books and other publications.

Last updated January 2025