By the Banks of the Tahan
The Bumbun hide overlooks a small man-made meadow with two trees at its centre, encircled by a wall of tropical wood and foliage. This brown moss-and-fallen-leaves-covered hideout is a window to this little opening in the rainforest. The two central trees contain rope-tied salt bricks to attract animals into the meadow.
gradually turned a soft blue. If there were a scale to measure the seamless and
smooth transition between night and day, it would have to be called by a new
name. The scale is fine, immaculate, and works at at-least two wavelengths: one
of the sky, another the forest. As we sat by the window hoping for the elephant
to return, the sky expanded its hues from the darkest to the lightest shade of
blue, the forest from a hazy, sleepy shade to a brilliant green. Against the
backdrop of distant calls of birds and the never-ending patter of water
droplets, the scene was set, excepting the dark-tailed tree rat (Niviventer cremoriventer complex)
dancing on the tree next to the hide, he never showed up.
In front of
the Bumbun hide lay a forest, among the oldest rainforests in the entire world,
of Taman Negara, simply meaning National Park. The window to this hide that
offered a vision at-best of 500-m is actually a primary rainforest stretching
over 50-km as the crow flies north, 88-km to the east, 38-km to the west, and
40-km to the south. It is an impenetrable forest, a forest where I again
suffered the endless forest effect – an illusion that the forests –
implying nature – is extensive and inexhaustible but in reality is a fragment,
and the ‘endlessness’ our figment of imagination.
is a sinewy, 50-km long river arising from Gunung Tahan – the tallest mountain
in peninsular Malaysia, flowing over a descent of 2000-odd meters, meeting
Tembeling River at Kuala Tahan. The Tembeling River itself is a tributary of
the sea-faring Pahang River that greets the South China Sea in the east. But
Tahan appears spindly only from space – its wide banks offer a perfect place to
contemplate and brainstorm, from statistical methods in the deep and dark rainforests,
to the fate of this ecosystem.
room talks and our walks by the river mingled in the rainforests: these forests
are so dense; it is quite difficult to sight wildlife. If you’re still with me,
think of it thus: if the tiles are dark, you may not easily be able to count
all your glorious hair fall, there will be some or many that you miss – what
you derive then is an estimate (a range between minimum and maximum).
is much easier, although gut wrenching. Counting animals is not, hence it is
often replaced by measuring occupancy – whether the space is occupied or not –
and abundance – how many occupy that space. The principle is the same, but my
colleague rightly pointed out to the nuances of occupancy versus abundance: larger
occupancy does not mean higher abundances, and both should be inferred
separately. To put it in our hair study, good news, hair-counters, having hair
spread over all the tiles doesn’t really mean you’re abundantly losing hair,
you’re perhaps just dancing a lot in the shower.
colleague’s cabin was often visited by the clouded monitor (Varanus nebulosus), and another’s by a
family of porcupines. One had a frog that lived in their pipes, its call
echoing through the entire area in the night, while rats and a troupe of geckos
that chuckled at odd times at odd jokes visited mine. It was a place by the
rainforest, after all, and they were all welcome.
touched the warm waters of Tahan River as we sped up stream, feeling the rush
of the rainforest. It came from the top of the mountain I could not visit, but
its waters connected me with the entire landscape. We swept past trees such as
the Neram tree (Dipterocarpus oblongifolius)
as ancient as they were tall, minarets of disproportional sizes, every living
tree an ecosystem in itself. While we did not see much except for the Rhinoceros
Hornbills flying higher up than the tallest reaches of the canopy, beneath it,
everything was practically invisible.
travelled at least 9-km up stream of Tahan River, by the rocky rapids of Lata
Berkoh wherefrom taking boats is not viable. A moderately sized tree that fell
on the path that leads to the cascade unfortunately made some visitors retreat.
On the way here we greeted the Talang tree (Koompassia
excelsa), one of the world’s largest trees growing over 50-m in height – an
emergent pillar of the tropical rainforests. In some walks I met with the Meranti
(Shorea sp.), Damar hitam siput (Shorea faguetiana), Meranti tembaga (S. leprosula)
– cousins of the central Indian sal trees! and Mengkundur (Tetrameles nudiflora) and Merbau (Intsia bijuga) – among the tallest Dipterocarps and Fabaceae trees
of the rainforests. I met every tree I could spend some time by with a warm
greeting – excepting the spiny palms such as Salacca sp. and the notorious Calamus
How I wish
I could converse with them. Would they, I wonder, reveal their secret to life,
and what it is they worry the most in the future? How many of these trees
remain, and how many of them will reach this gargantuan stature?
Yet as much
as I enjoyed their company, I still carry a painful gash courtesy of a
not-so-friendly burly Macrotermes carbonarius termite major soldier, and
saved myself another painful one by the Camponotus
gigas ant (macro as in large, and
gigas as in giant, I got acquainted
by the nomenclature used by taxonomists of rainforests fairly quickly, I’d say).
a country known for its underground oil reserves and aboveground oil palms. It
is the second largest exporter of palm oil products by volume, after Indonesia.
Oil palm and rubber replaced many of conventional agricultural areas, now
covering over 84% of the total land under agriculture. At one point, palm oil
was considered an important breakthrough in use as a biofuel agent. We know
that oil palms are among the biggest direct threat to rainforests wherever they
are built, but what remains to be known – or measured, or counted – is the
impact it will have at a global scale if palm oil use was slashed. When the
European Union recognised the fact that oil palms result in deforestation (only
this year), the PM of Malaysia alleged a risk of trade war instigated against Malaysia
and a threat to the people in oil palm business (more on it on Wikipedia) – farmers who saw a trade boom and
shifted their crops.
iconic butterfly the Malayan Red Harlequin (Paralaxita
damajanti damajanti), Malaysia represents two ends of a spectrum, from
azure blues of its waters to the ruby reds of its forest denizens, and everything
in between that we do.
At six o’clock in the morning everything is pitch dark. I peer into the darkness, my mind stuck on my colleague’s narration of a rendezvous with a lone elephant the morning before. He saw the tusker emerge from the wall, gripping at the tender grass blades as he made his way to the salt lick, took a few large chunks out of them, and disappeared into the wall. It has been nearly a decade since an elephant ventured by the Bumbun hide, we’re told.
|6:36, 6:42, 6:53 at the Bumbun hide|
|View from the Bumbun hide, and the actual expanse of Taman Negara|
We had congregated by the meeting point of the Tahan and the Tembeling rivers to discuss, first, how to find that one animal in the large forest – the needle in a haystack, if you will. Second, how to conserve something that is so hard to find. And third, using numbers in grassroots conservation.
|Tahan River: emerging from Mount Tahan and meeting the Tembeling River at Kuala Tahan|
My favourite way to imagine the number game is to count hair on the bathroom floor. If I still have you with me, and if you’re short-haired (there’s also some talk for the long-haired later), you may find your hair randomly placed on the tiled floor after shower. If these tiles are square in shape, and like me if you want to keep a track of your hair fall, you simply count the hair in each tile, and sum them. If the tiles are a lighter shade, easy peasy.
|Were it not for the boardwalks, we'd be covered in leeches. In ecological studies, however, |
these dense jungles present a more pressing problem: of detection.
Furthermore, in forests, animals are distributed randomly, influenced by some natural principal, such as availability of food, roost, nursing site, among many others – they also have a fluid but measurable space or home range that they maintain. Solitary, small mammals generally have smaller home ranges. I apologize, there’s more on hair here: short-haired people, draw an imaginary circle on each and every hair that’s fallen on the tiled floor, that’s the space your ex-hair represents on the floor. If the tiles are smaller, your hair’s home range fits appropriately in that tile with some overlaps.
Now for the long-haired ones: draw a circle on your ex-hair, and you will see that if the tile is small, the longer the hair, the more the number of tiles it covers, and by definition you will end up counting the strand of hair as one for every tile it sprawls across. This tile-by-tile counting wouldn’t work, for that will result in a multiple count of hair fall. In case of some herding and most large-bodied animals, their ranges are large, hence there are multiple chances of recounting them because they move around a lot.
Now replace the tile with a grid and the floor with the forest, and the problem remains: large-bodied animals such as gaur and elephants and herding animals such a wild pigs have large territories, hence if your grids are small, you may encounter them in every grid as they move about while you count them. This double-counting overestimates the animals present, and may even give an illusion that the forest is healthy, when we are only counting ghost animals! Theoretically, a grid slightly larger than the animal’s home range will be able to restrict double counting.
|While every ecosystem poses its own problems of population studies, the rainforests certainly take the biggest bite: |
they are diverse but difficult to detect, and in it lie all the idiosyncrasies.
Statistics takes us further into the number game. I was introduced to the Royle-Nichols occupancy estimation in our talks which exploits the dynamic nature of animals: “variation in abundance induces variation in detection probability”. In other words, heterogeneity (or differences in arrangement of things) in abundance can be measured as heterogeneity in detection probability. In our hair study, it means your hair sometimes gets bunched together or spread unevenly with the flow of the water as you’re counting, making effectively counting a hassle.
When covering any study of hair fall, however, care must be taken that you clear the bathroom of the previous hair fall event, least you count the old shed hair (or add someone else’s to your count!) and overestimate at your own misery. In population studies, it is important to assume that populations are geographically and demographically closed for the study duration. Any immigration or emigration will violate that assumption, and the answers will generally be over or an underestimation of the near-actual. For our hair study, the sampling occasion has to be one shower event.
Over a period of time, the rainforest population – or bathroom hair fall – study will give you the dynamics of populations – or trends in hair fall. One excellent example is using Wildlife Picture Index, a novel idea that measures changes in biodiversity from the occupancy estimates using camera traps. A study by Dr Jorge Ahumada and his colleagues in Costa Rica found interesting trends in wildlife populations by analysing camera trap records over a period of four years; that’s one each closed-population camera trap session per season. They found that the Lowland Paca and Central American Agouti showed significant declines in occupancy, likely linked to targeted hunting, and possibly with interspecific competition and an increase in predator densities in the same period. Well, what I should be looking at is whether coconut oil, egg, or beer reduces my hair fall over time.
Every time I moved out of the meeting room, my eyes would scan the horizon for tropical birds, birds I had never seen or heard. A pair of Little Green Pigeon picked small fruits on the banks of Tembeling River every morning. The echoes of the barbets from the depths of the rainforests filled the afternoon air, the plantain squirrels danced about the fern-clothed trees, and the long-tailed macaques squatted about my cabin every afternoon.
One night on the way to the Bumbun hide, we saw two turquoise eyes glinting in the torchlight. Those frozen eyes froze us in our steps, but curiosity got the best of us and we decided to take a closer look. Silently, as we moved closer, the owner of the eyes looked to the side, identifying itself as the mouse deer – not fifteen feet from where I was! This shy woodland creature is hard to come by, and this one politely fed in the rainforest understorey as we watched from a small gap in the trees.
|The clouded monitor - an excellent climber, is also quite tolerant of people, except when you disturb him during his sun basking session, like I did and got threatened in return.|
Understanding population biology is a key to conservation of that species, or the species that depends upon that species. While every ant and elephant talk excited me, we were here to discuss tigers and tiger-prey population studies; how do we protect them? Among the biggest threats to large mammals is poaching, either for the international wildlife trade or for meat. In Malaysia, our colleagues, in partnership with local communities and park authorities, started extensively combing forest areas to track movement of poachers and destroy wire snares. Called Project Stampede, it comes on the heels of the latest numbers for the country: only 180 Malayan tigers (formerly Panthera tigris malayensis, now P. t. tigris) remain, with an increased threat of extinction to tiger-prey population such as sambar (Rusa unicolor). The snares removed were at least a centimetre thick, aimed specifically at targeting large mammals.
In the neighbouring country of Thailand, the Indochinese tiger (formerly P. t. corbetti, now P. t. tigris) is also witnessing this crisis. About 4,000 snares were destroyed within a year in 2013-14. Here, the snares varied in size – they were mostly small, indented for smaller mammals, perhaps for the pot.
Only a day after my return, a news report published outlined how large carnivores – the Indochinese tiger, the Indochinese leopard (Panthera pardus delacouri), and the clouded leopard (Neofelis nebulosa) along with small and large wild ungulates, fell prey to poachers with guns, snares, and foot traps. The tiger and the leopard are now extinct in Laos, soon after they vanished from Vietnam and Cambodia. Only hope remains with Thailand and Myanmar. The Malayan tiger is hanging by an even finer thread – within 7–8 years, 60% of the population fell prey to poachers, the population collapsing from around 60 to 23 in Belum-Temengor – a forest in northern peninsular Malaysia continuing into southern Thailand, larger than Taman Negara.
|Up the Tahan River we go, the minarets of the rainforests guiding our destiny.|
This invisibility makes detection difficult. A new method is to use the river to collect this information, but how do we do that? Enter environmental DNA, or eDNA. A little cup of water collected from various locations in a flowing river contain DNA residues of species inhabiting that area. Used to identify the presence of elusive and rare animals – from mammals to fishes, this tool serves as an important precursory assessment before intensive studies are undertaken.
Population studies however pose a different kind of a problem we could not discuss in our hair example due to the gross-factor. In population studies, how do we avoid double counting, or underreporting, of animals that have no distinct marks moving freely about – as is the case with most wild ungulates? Imagine marking your hair to identify every individual hair fallen as they move about in water. No, right?
In such cases, models are being designed called “mark-resight” where, unlike mark-recapture, the “marked” individuals live in a population with “unmarked” individuals and no new marked individuals are introduced in the population (more on it here). These marks may be artificial (dyes, tags, collars) or natural (patterns, scars, and oddities such as a broken ear). For animals like the wild pig, sambar, and other tiger-prey species without distinct markings – including bears – mark-resight is becoming an increasingly promising tool to assess abundances and densities.
|The emergents of the rainforests (clockwise from top), the Talang tree, |
among the tallest in Taman Negara, the Mengkundur, and a relatively young Talang tree.
The beautiful designs of Taman Negara (clockwise from top left): the curious leaves of Trevesia burkii, the giant epiphytic fern Asplenium nidus, a coal-dark fallen leaf, and the blue-hue of the peacock fern (Selaginella willdenowii)
Our third talk was on taking the numbers back into the wild and “tracking the finer details of the growth” as my colleague put it. WWF’s Tigers Alive Initiative envisages doubling tiger numbers by 2022 in areas that have promise. However, recovering tiger populations is not an exponential process. There are finer details and tonnes of local (such as oil palm) and global nuances (such as illegal international trade in wildlife) that need to be addressed to achieve a sustained growth. My colleague put forth four scenarios of recovery, each scenario requiring different ways to address concerns; the rapid recovery scenario where tiger populations bounce back in a short period – either because of good connectivity to source sites or good prey density and low people densities. The tiger recovery depressed scenario where the conditions are conducive but tiger recovery appears to take time due to some anthropogenic pressures. The prey-recovery dependent scenario where tiger recovery depends mostly on prey density augmentation; and the low prey and low political support scenario where tiger recovery depends on social transformation. Every scenario requires longer period of recovery. In conservation – of tigers or any species of concern, the management falls within a gradient of these scenarios.
|The giant arthropods (clockwise from top left): Giant forest ant, |
giant millipede, and the giant forest termites
Well, if only I could take every bite to experience the pain of a thousand lives a rainforest feels. Allow me to address the elephant in the room: Elaeis guineensis, the oil palm. To be honest, my introduction to the tropical rainforests of South-East Asia wasn’t by the banks of Tahan River, although it was here that I reflected upon its diversity and diverse threats. It was many years ago, in biology textbooks, for their rich biodiversity but also for the oil palms gnawing at them from all sides.
My maiden visit to SE Asia was also along the same lines. As the plane flew over the Malacca strait, the rich mangrove forests, hugging small islands in deep-azure waters, stood out like green terrestrial clouds. The deltas of many-a-rivers arising somewhere in the mountains embraced the seas in a wide embrace, and as seas made way for land, I imagined minarets of Dipterocarps rising to the sky, only to be broken by the reality pockmarked in an otherwise uniform shade of green – new land preparations for upcoming oil palms.
|Pages from Earth's textbook: the oil palms to the left, and the tropical rainforests to the right.|
Gazing into the arm of the Milky Way one clear moonless night, the waters of Tahan River gently lapping up the sandy bank, I wondered if we are missing the subtleties of economy being a part of ecology. In the meeting room, my colleagues discussed econometrics and the usage of Dow Jones Indices in nature, and I confess that while both offer out-of-the-box ideas to balance our cheques and equations, I was helplessly hoping for a harlequin to hover by. And one did, one late evening.
|The Malayan Red Harlequin|
Gunung = mount/mountain
Kuala = confluence
Lata = waterfall
Taman negara = park of the nation
Views expressed here are strictly mine and do not reflect the views of any individuals or of my organisation.