Logo: Gliding mammals of the world

The world’s gliding mammals are an extraordinary group of animals that have the ability to glide from tree to tree with seemingly effortless grace. There are more than 60 species of gliding mammals including the flying squirrels from Europe and North America, the scaly-tailed flying squirrels from central Africa and the gliding possums of Australia and New Guinea.

Colugos: Early observations

The first mention in Western literature of the existence of the colugos was probably in History of Java by the early 17th century Dutch physician and botanist Jacobus Bontius, who spent his last years in the Dutch East Indies. It was not until many years later that illustrations of these animals began to appear. In 1774, the German naturalist Johann Christian Daniel Schreber began writing a multi-volume set of books on the world’s mammals entitled Die Säugethiere in Abbildungen nach der Natur mit Beschreibungen. This work was important because many of the animals included were given a scientific name for the first time, following the binomial system which Carl Linnaeus had established in 1758.

In 1780, the German zoologist and botanist Peter Simon Pallas recorded his observations of colugos in Acta Academiae Scientiarum Imperialis Petropolitanae. Most of these observations are largely fanciful, especially their ability to fly, although their probable relationship to primates was made with the suggestion they were ‘winged apes’. Pallas wrote:

The description which I had prepared almost sixteen years ago of a very rare animal, from the continent of eastern India and its islands, may finally come to the light of day, as I had promised some time ago; it has been rather perfunctionally treated even by the most recent zoologists, and certainly not known from autopsy. I have had the good luck in various museums, which I have looked through completely, to examine four specimens of different ages of this animal, known by the Linnaean name ‘Flying Lemur’; in these matters it will be of benefit to put in to writing whatever I observed, until some wandering zoologists may open up the treasure house of the Indies for us.

Before I set out my own observations, it will be appropriate to put forward a précis of the authors who have touched on the animal of which I speak. Bontius first made mention of it, unless I am mistaken, and this man has left more details about it than anyone else. He writes, ‘in Gujarat in India there exist amazing bats (as he correctly calls them), who fly in flocks in the manner of the wild geese, wandering in the air around evening, or hanging from trees, and who are through their mass, in which they equal a cat, and their extraordinary shape, an amazement to strangers. The Belgians have given them the name "winged apes".’

The Malayan Colugo by Peter Simon Pallas
The Malayan Colugo by Peter Simon Pallas from his Galeopithecus volans, camellii Descriptus. Acta Academiae Scientiarum Imperialis Petropolitanae published in 1780.

In 1799, the natural historian and artist Jean Baptiste Audebert described the Malayan Colugo and a rufous-brown form of the Philippine Colugo in Histoire Naturelle des Singes et des Makis. He made some interesting, though often inaccurate, observations including their ability to fly like birds or bats:

The animals of this kind were described by travellers under the names of flying cat, flying civet, flying monkey and flying fox; and by some taxonomists under that of flying lemur ... All the digits of Galeopithecus are joined together by a membrane, rather like those of web-footed birds. They are bunched together, and shaped like the blade of a knife: the nails are large, flattened on the sides and very curved and pointed ... moreover, it is easy to see that these animals can cling to the branches of the trees by inserting the sharp points of their nails in the bark, as squirrels do; but the membrane which covers their limbs right to the nails would seem not to allow them to make such lively movements as those of the latter animals...

The russet-red Galeopithecus was described and drawn by [Albertus] Seba under the name of ‘Chate de Ternate qui vole’ [flying cat of Ternate]. It flies quickly, he said, but very low, rather like our bats, circling as it looks for food. The description of Seba is correct, but his illustration does not show the unusual shape of this animal’s digits...

This Galeopithecus lives on the islands of the Indian Ocean. The following passage is found in An Account of the Pelew Islands, and seems to me to refer to the animal in question. ‘As they were seated close to the king, they saw a flying fox in a nearby tree; Captain Wilson’s servant, who had just returned from hunting and still had his rifle loaded, killed it. This animal resembles our bat, but it is five to six times larger; its head is like that of a fox, and its odour is the same. The natives call it Oleck. It runs along the ground and climbs up the trees like a cat; moreover it has wings and can spread them very well, which enable it to fly like a bird. The natives of Pelew eat them, and find them delicious...’ The most remarkable feature of Galeopithecus is the membrane which covers it, and which adheres to the four limbs and the tail. It runs from the chin right to the nails of the front feet, from there to those of the back feet and then it goes on to join the tip of the tail...

Because of its power of sustained flight, Galeopithecus are like the bats and flying squirrels; but they differ from the latter in that their membrane has a greater surface area; also flying squirrels can only glide, while Galeopithecus fly like the birds, according to Captain Wilson, and can fly in circles, according to Seba; but it is probable that the style of flight of these animals is not as sustained as that of the bats. These have true wings, formed by the membrane which wraps the long digits of their forelimbs, and give them the ability to beat the air in any direction, and to move very rapidly. With Galeopithecus, however, the head, limbs and tail are included in the membrane and the range of movement must be less; this movement must be somewhat jerky, and is midway between the gliding of flying squirrels and the flight of bats.

An illustration of a colugo by Johann Schreber
An illustration of a colugo by Johann Schreber in his Die Säugetiere in Abbildungen nach der Natur mit Beschreibungen, published between 1775 and 1787.
An illustration of the Philippine Colugo
An illustration of the Philippine Colugo from Audebert’s Histoire Naturelle Des Singes Makis published in 1799.

In 1800, the zoologist George Shaw made some further observations of the Malayan Colugo in his book General Zoology or Systematic Natural History, repeating the previous inaccurate observations:

This singular animal ... is a native of the Moluccas and Philippine islands, where it is said to frequent woody places, and to feed principally on fruits. It almost constantly resides on trees, and makes use of its membranes in the same manner as the flying squirrel. In descending from the top of a tree, it spreads its membranes, and balances itself to the place it aims at in a gentle manner; but in ascending it uses a leaping pace. It has two young, which are said to adhere to its breasts by the mouth and claws. The whole length of the animal is about three feet: the breadth, when expanded, nearly the same: the tail is slender and about a span long. The membrane, or expansile skin, by which it is enabled to fly, is continued, on each side, from the neck to the forefeet; thence to the hind feet; and again to the tip of the tail: it is not naked, like the skin of a bat’s wing, but covered with fur, in the same manner as the body: the inner or lower side, however, appears membranaceous, and is marked by numerous veins and fibres dispersed through it.

Camelli, in his enumeration of the animals of the Philippine isles, published by Petiver in the Philosophical Transactions, describes it as about the size of a cat, shaped like a monkey, but more slender, and of the length of about three spans from head to tail; but adds, that in some parts it arrives at a far larger size, so as to equal a Chinese umbrella in expanse. He describes the colour on the upper parts as dusky, and elegantly variegated with whitish streaks on the back, running beyond the body over the flying membrane: the face he compares to that of a monkey, and the manner of flight to that of a flying squirrel. Camelli adds, that the young adhere to the teats of the parent by their mouth and claws; but it is remarkable, that in his manuscript on this subject, now preserved in the British Museum, he expressly asserts that the female is furnished with two sacs or pouches on her belly, in which she carries her young while suckling ...

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Gliding Mammals of the World provides, for the first time, a synthesis of all that is known about the biology of these intriguing mammals. It includes a brief description of each species, together with a distribution map and a beautiful full-color painting.

An introduction outlines the origins and biogeography of each group of gliding mammals and examines the incredible adaptations that allow them to launch themselves and glide from tree to tree.