Colugos, or Snapshot of Life in a Snuggie

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What on earth is a colugo?!?  Sloth in a snuggie?  The potoo of mammals?  Despite the erroneous common name, “flying lemur”, colugos are gliders belonging to their very own distinctive group, the Order Dermoptera.  The share a common branch of the phylogenetic tree with treeshrews (Scandentia) and primates (Primates).  Malayan colugo (Galeopterus variegatus).  Image credit: David Yeo via gettyimages.

While researching last week’s post on specialized comb-like grooming structures in a variety of mammals and searching online for images of colugos, I noticed an astonishing number of photographs taken of this animal caught in the middle of, well, taking a poop.

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What is going on here?  Image credit: Crystal and Byran in Singapore.

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OK, I’m getting the picture here.  Image credit: My Blog.

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Image credit: Ecology Asia.

The pose is striking.  Colugos are enveloped in a snuggie-like wingsuit that extends around the body to form a gliding membrane called the patagium.  The rather long tail is also entrapped within this fabric of loose skin, looking like the pointed end of a diamond-shaped kite.  In order to keep this delicate membrane clean and in good order, defecation and urination happens in a vertical “standing” posture — usually the animal clinging on the trunk of a tree — and flipping up the tail, inverting the patagium over the back and exposing the nearly naked skin of the underside (Dzulhelmi & Abdullah 2009).  Wharton (1950) makes further observations on colugos captured from the wild.  Note that colugos are misleadingly termed “lemurs” here:

Captive lemurs can be stroked without much offense to the animals.  A sweet agreeable odor surrounds them.  They are clean.  When wet or dirty they can not rest until they have groomed themselves thoroughly.  To avoid solid excrement, which is a goat-like pill, or to urinate, they hang by the front legs from a branch, drop the hind legs and curl the tail over the back.  A pocket-like space just exterior to the anus is opened by this action.

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Step 1.

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Step 2.

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Image credit:  Step 3. Terrific series of a colugo doing its business. A vegetarian diet of leaves, flowers, fruits, buds, sap, and nectar keeps you regular (Dzulhelmi & Abdullah 2009). Image credit: tHE tiDE cHAsER.

Being caught at the toilet is a vulnerable moment for all of us, but perhaps even more so for the shy, elusive colugo continuously spotted by wildlife photographers.   And colugos seem to radiate an aura of adorable haplessness.  Specialized for living up in the trees, a colugo on the ground is practically useless until it can flop over to the nearest vertical surface and hop-climb up to safety (Wharton 1950; Dzulhelmi & Abdullah 2009).  Its chief defense against threat is camouflage and if that fails, quietly sidling around to the other side of the tree trunk in an “unnoticed escape” maneuver (Dzulhelmi & Abdullah 2009).

Image credit: Gehan de Silva Wijeyeratne via

“Please don’t look at me.”  Image credit: Gehan de Silva Wijeyeratne via Wildlife and Travel.

Colugos can also potentially glide away from danger.  Gliding has evolved independently many multiple times within mammals, but colugos are probably amongst the most impressive.  One animal was recorded to have traveled 136 meters (446 feet) with only a 10.5 to 12 meter (34 to 39 foot) loss of elevation (Nowak 1999).  Many glides have been measured to be over 100 meters (328 feet) (Nowak 1999; Vaughan, Ryan, & Czaplewski 2015).

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The gliding membrane, or patagium, extends from the neck to forelimbs, between the fingers and toes, between the limbs, and from hindlimbs to tail.  The membrane is supposedly so thin that it is almost possible to read through it (Wharton 1950).  This particular colugo is a mother, with a single youngster clinging across the belly like a belt.  Females usually give birth to one offspring after 8 weeks gestation and keep the baby enclosed within the patagium like a hammock for 6 months.  As the youngster grows, gliding decreases (Dzulhelmi & Abdullah 2009).  Image credit: Cede Prudente Blog “Wildlife Photography in Borneo.”

Gliding most likely evolved as a foraging strategy to move quickly from one food-bearing tree to another (Vaughan, Ryan, & Czaplewski 2015).  Colugos travel predictably from their tree hole dens in a daily nocturnal commute through the forest.  While this routine is convenient for photographers and the few intrepid scientists studying colugos, this behavior pattern has also been utilized by the native peoples of tropical southeast Asia who hunt these animals for their scant meat and soft, luxurious fur (Wharton 1950; Dzulhelmi & Abdullah 2009).  Wharton (1950) published a natural history of a colugo (Cynocephalus volans) species found on the Philippine island of Mindanao, which included this account (again, he uses the erroneous term “lemur”):

My Manobo companions indicated the path taken by the lemurs in leaving this particular tree, and told me that several weeks previously several natives had shot at the lemurs with bow and arrow.  Indeed, an arrow was still sticking in the side of a nearby mamacoa tree. . . . From a cavity 45 feet above the ground a head appeared and a lemur shuttled out and around the trunk.  It hesitated a moment and, with a twisting, outward leap, spread its membranes.  It dropped very steeply for perhaps twelve feet, then swooped across to land on the mamacoa tree, practically on top of the arrow which was impaled there.  Shooting the animal seemed to be a simple problem with the natives, once the exact landing place was determined, for experience showed that the animal would land on that spot the next time.

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Image credit: BBC Earth via YouTube.

Perhaps spurred by this curious observation in the forest, Wharton engaged in a rather unkind test of the single-minded flight path of the colugo:

Once, as an experiment, I repeated tossed a lemur from a tree about thirty feet high.  It always chose to sail towards a group of palm trees that stood near the beach.  Since the animal was obviously not in top shape and the direction it chose was down wind, it would invariably land heavily on the ground about forty feet from the tree with no obvious attempt to break its fall with its legs.  Lemurs are known to be of a low order of intelligence.

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Image credit: ImgKid via ZME Science.

Dodging the occasional human hunter and inquisitive zoologists of the “hands-on” variety are probably now the least of the colugo’s worries.  Utterly dependent upon forests, colugos are facing the consequences of massive deforestation in southeast Asia.  While it appears that their populations are either holding steady or only declining at a slow rate, thanks to an ability to tolerate disturbed habitat and adapt to secondary forests or plantations, there is still enough of a mystery surrounding the biology of colugos to prevent any confident declaration of their long-term future.

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What’s not to love?  Image credit”  Hendy Mp via Tumblr.

References

Boaeadi & Steinmetz.  2008.  “Galeopterus variegatus.”  The IUCN Red List of Threatened Species 2008.  Accessed 10 October 2016.

Dzulhelmi, M.N. & M.T. Abdullah.  2009.  “An ethogram construction for the Malayan Flying Lemur (Galeopterus variegatus) in Bako National Park, Sarawak, Malaysia.”  Journal of Tropical Biology and Conservation 5:  31 – 42.

Gonzalez, J.C. et al.  2008.  “Cynocephalus variegatus.”  The IUCN Red List of Threatened Species 2008.  Accessed 10 October 2015.

Nowak, Ronald M.  1999.  Walker’s Mammals of the World, Volume 1, 6th edition.  Baltimore, MD:  The Johns Hopkins University Press.

Vaughan, Terry A., J.A. Ryan, & N.J. Czaplewski.  2015.  Mammalogy, 6th edition.  Burlington, MA:  Jones & Bartlett Learning.

Wharton, Charles H.  1950.  “Notes on the Life History of the Flying Lemur.”  Journal of Mammalogy 31 (3):  269 – 273.

 

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