Posts on Borneo

On the Wings of Dragons

14 January 2015

If you’ve ever been on a walk in the rainforests of Borneo you may have experienced this not-uncommon occurrence: out of the corner of your eye you glimpse a leaf falling down from the canopy, only instead of it continuing down to the forest floor it abruptly vanishes onto the side of a tree. It might take a few moments to register, but suddenly you realize that there was just something not quite right about the trajectory of that leaf. A keen eye (and often a pair of binoculars) and a scan of the tree trunk will reveal the real culprit of the fraud: a gliding lizard. And, as it turns out, you were meant to be deceived.

With over 40 species distributed across Asia (and 10 in Borneo), Draco lizards are perhaps the most effective gliders in the animal kingdom. Although typically measuring less than 20 cm from nose to tail tip, they have been recorded gliding over 50 meters in a single leap. This is achieved by extending a flap of skin (patagium) on their sides which is supported by movable ribs, effectively turning the reptile into a miniature frisbee. Steering in mid-flight is controlled by the tail and perhaps also by the front legs which are pressed over the top of the wings while airborne.

Within a forest habitat the ability to glide is an enormous advantage and this may account for why these lizards are so successful and species diverse. Traveling from tree to tree with ease, Draco are able to forage over a greater area (they feed predominantly on ants) as well as escape certain predators without ever having to descend to the ground. Flight, however, brings with it certain dangers, and although the lizards are highly camouflaged when perched against tree bark with their wings concealed, their movements through the air put them at risk from detection by keen-eyed predatory birds.

A newly published paper in Biology Letters (see link below), with research supported by the National Geographic Society, finds evidence that the patagia of several Draco species mimic the color of dead leaves, providing the lizards with effective camouflage even while in flight. Researchers measured the color of Draco wing membranes and compared it with the color of fallen leaves occurring in the vicinity. Amazingly, a color correlation was found not only between each species’ patagia and the color of the most abundant falling leaves in their preferred habitat, but two separate populations of a single species (D. cornutus) matched the predominant leaf color at the different locations they were found in: reddish-brown mangrove leaves vs. dark-brown lowland forest leaves. More work remains to be done to substantiate this trend in other populations and species of Draco.

Studies like this continue to decipher the amazing minutiae of adaptations that rainforest organisms possess and show that, in a habitat teeming with predators and prey, deception plays no small part in the struggle for survival. Next time you see a leaf falling down through the forest, have a second look – in the jungles of Borneo things aren’t always what they seem.

Draco cornutus

References:

Klomp DA, Stuart-Fox D, Das I, Ord TJ. 2014 Marked colour divergence in the gliding membranes of a tropical lizard mirrors population differences in the colour of falling leaves. Biol. Lett. 10: 20140776. http://dx.doi.org/10.1098/rsbl.2014.0776

A Tale of Two Kitties

30 May 2014

Several days ago whilst hiking up a hill in Danum Valley to check on one of my camera traps, I had a chance encounter with one of Borneo’s most beautiful creatures: a Marbled Cat (Pardofelis marmorata), the first I have ever seen. I was about to ford a creek at the bottom of a small gulley and noticed something moving in the undergrowth on the opposite bank. The cat was so perfectly camouflaged that I didn’t realize I was staring directly at it until it moved again. About half a metre in length with a tail at least as long again, it was beautifully patterned with dark and tan blotches. It had seen me already (of course) and was slowly slinking away up the stream bank.

As luck would have it I had just left my camera in a hide a few hundred meters down the trail so taking a photo was out of the question. Without thinking I raised my hand to my lips and squeaked out a simple rodent alarm call. The cat stopped in its tracks and turned around, staring at me. Unbelievably it then began stalking back down the stream bank towards me until it reached a point on the opposite bank less than 4 meters from where I stood. We locked eyes for a few seconds, the cat trying to decide exactly what was going on, and me just trying to savor as much of the experience as I could while keeping my heart rate at a reasonable level. A moment later it turned and sulked away, uttering a low growl as it went, and disappeared quickly among the underbrush.

I glanced at my watch: 10:30 AM sharp. Bright sunny day and blue sky. While we normally think of the shy wild rainforest cats as strictly nocturnal, or even crepuscular creatures, it seems that the Marbled Cat is often active during the middle of the day. My good friend Dr. Jedediah Brodie, who has done a enormous amount of camera trapping in Borneo for his research on mammal ecology, thinks that this cat may use daylight hours as a means of avoiding confrontations with the apex carnivore of Borneo rainforests, the Sunda Clouded Leopard (Neofelis diardi diardi), which is more active at night and early morning. Although confusingly similar in coloration, the Clouded Leopard is several times larger than the Marbled Cat and wherever present would occupy the role of top predator without dispute.

As if just to prove a point, twenty minutes later and another 500 meters ahead on the trail I crouched down to examine the catch on my camera trap which had been running for the past two weeks, and a possible reason for the Marbled Cat’s diurnal habits became clear – a Clouded Leopard had been on the prowl just the night before:

Sunda Clouded Leopard (Neofelis diardi)

With five species of wild cats, Borneo is exceptionally rich in felid species even were it not an island. In addition to the Marbled Cat and Clouded Leopard, Borneo is also home to the Leopard Cat (Prionailurus bengalensis), Flat-headed Cat (Prionailurus planiceps), and arguably the least known of all the world’s cat species, the rare endemic Bay Cat (Catopuma badia). All except for the Leopard Cat, which survives well in disturbed habitats, are under threat due to habitat loss and poaching, making them the focus of long-term studies and conservation efforts.

On Assignment: Batang Ai

9 October 2013

On assignment: Batang Ai

One of Sarawak’s Heart of Borneo zones, Batang Ai National Park comprises over 270 sq. km. at the headwaters of the Ai River, above the Batang Ai hydroelectric dam. This traditional homeland of the Iban people is a beautifully rugged wilderness, with undulating hills of pristine forest accessible only through a vast network of clear water rivers and streams. In addition to hosting numerous rare and protected species of wildlife, the park is home to an estimated 300-350 individuals of Borneo’s rarest subspecies of orangutan, Pongo pygmaeus pygmaeus.

Since February this year, I have made a series of expeditions into the interior of this region on assignment for Borneo Adventure, a local company that has pioneered the area’s ecotourism and worked with the Iban people to develop a sustainable conservation strategy. My work was aimed at producing images for a book showcasing the rich natural and cultural heritage of Batang Ai and the neighboring areas. After a total of six weeks in the forest, enduring torrential rains, an enormous enraged orangutan, and several destroyed cameras (including one plunging into the river with a 600mm lens, and another having its innards invaded by an army of tiny stinging ants) I tallied over 6000 captured images. Shown below is a sneak peek view of a handful of the photos. The book is scheduled for publication and release in early 2014.

Potter waspHeadhunting relicsPhrynoidis asperaFungi
River fishingAerial viewWeavingPitta granatina
Pongo pygmaeus pygmaeusChloropsis cochinchinensisNeurobasis longipesHeadwaters of Batang Ai


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