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“The Pale Rim Around Her Wings”
by Chris Eckstrom
Borneo, The Infinite Tapestry
Forgotten Edens, National Geographic Society, 1993
In the night she was almost eaten by a tarsier. It was late evening, but she still rested where she had hidden all day, concealed along the midrib of a leaf. She’s a katydid, and her body, luscious green and veined like a tender new leaf, is a perfect disguise for avoiding capture by day: Even the pale rim around her wings helps to compensate for any shadow her body might cast that could guide a hungry bird or lizard to her. In the cover of night, she feeds on leaves, and listens. The rain forest around her is so black that you would not see that the trees rise twenty stories above her, but you might feel that the canopy reached even higher into the sky by the sheer enormity of sound pulsing inside the forest. Wild trills and shrieks, piping bells and low hoo-o’s overlay the steady rasping and buzzing and deep rhythmic thrum that comes from every layer in the stair-stepping tiers of the forest. Through the shrill whines of mole crickets, the metallic clinks of tree frogs and the swelling chirrs of unfathomable numbers of insects, she heard a male katydid singing. She picked up his song with tiny hearing organs on the joints of her forelegs. He was calling for a mate, and she responded. She crept to the tip of her leaf and waved her forelegs to home in on his position. Just above her sat a tarsier, a primate the size of a human hand. He clung to a sapling, his papery ears perked out like sails to the wind, his giant eyes open wide to see through the darkness. He sensed her movement, spun his gaze to her leaf, and sprang, but she flew just in time, a sudden whir swallowed up in the great drone of the night.
The symphony of cries surrounding the katydid speaks to the extravagance of life in her rain forest home. She lives deep in the lowland forest of Borneo, the huge island that forms the lush green heart of the Malay Archipelago. Shaped like a big ragged raindrop, Borneo straddles the equator between Southeast Asia and Australia. It is the third largest island in the world, filling an area the size of the eastern United States from Maine to Florida, much of which is covered in rain forest. Politically, Borneo is shared by Indonesia and Malaysia, with the tiny nation of Brunei wedged along the northwest coast. Geographically, the island is fringed with mangrove swamps and palm forests and the mouths of scores of dark rivers that snake inland through towering rain forests. From the coastal lowlands, the land rumples and rises to a mountainous central plateau of 6,000-foot highlands, the headwaters of all the big rivers. In the far north, one lone magnificent peak, Kinabalu, stands 13,455 feet high above the rolling sea of forests below, the highest mountain in Southeast Asia.
Ecologically, Borneo is a center of biological richness for the Indo-Malayan region--and a hot spot of world biodiversity. Twenty-five acres of Bornean rain forest holds more species of trees than occur in all of North America. Borneo shelters more varieties of birds than are found in Europe, as many mammal species as live on the continent of Australia. For reptiles and amphibians and other families of life, the statistics are equally high, but for the insect world, the figures are staggering. They comprise literally millions of species--the majority of life forms in the rain forest---and so overwhelming are their numbers that only a miniscule percentage have been described by science. On Borneo, the little katydid perched on the leaf she mimics symbolizes both the complexity and mystery of the rain forest: Her survival depends, in part, on her camouflage, and on the leaf she has evolved to match, in a great forest whose entire fabric is an infinite tapestry of connections between species like hers. But while we may speculate on her ecology based on what is known of other katydids, the one that whirled off into the night’s black maw has not yet even been named.
The forest that sustains such a wealth of life has the stature of a grand cathedral. The tallest trees in the Bornean rain forest soar to heights of 250 feet, higher than trees in Amazonia and Africa. They are the emergents, and they spread their boughs above the undulating roof of the forest canopy, open to the force of the sun and the wind. Most of the emergents and canopy trees are members of a family known as the dipterocarps, a word meaning “two-winged seed,” which the trees produce in periodic flushes, or mast fruitings, filling the forest with showers of brown whirligig seeds. They fall like swirls of spinning maple leaf pods in the spring, drifting down through a world that is bathed in a pale green, perpetual twilight. Only two percent of the sunlight that shines on the canopy filters down to the forest floor. The air inside is calm and heavy with moisture, and from the lacy boughs of the highest trees down to the great buttress roots that support them, the forest is layered with dense tiers of vegetation that shelter kingdoms of creatures both strange and magnificent. It is a world where giant squirrels grow larger than tiny mouse deer and delicate moths patterned like Indonesian batiks float by on nine-inch wings. Through the dark halls of the forest roam elephants and two-horned rhinoceroses, white-bibbed sun bears with shiny black fur and sleek clouded leopards that stalk the night. There are bearded pigs, barking deer, scaly pangolins--and white moon rats that emerge like pale ghosts after dark. Through the trees flit broadbills the color of emeralds, brilliant pittas jeweled in garnet and blue and hornbills with huge upcurved casques on their bills that work the canopy with lasso-whip wingbeats. High up swing solitary orangutans and troops of sociable gibbons, whose liquid bubbling songs ring through the forest at dawn; lower down live bushy binturongs with prehensile tails and along the rivers, proboscis monkeys with pendulous noses and partially webbed feet. There are insects that look like twigs, horned frogs that resemble dead leaves, and exquisite flower mantises precisely formed like the petals of an orchid--a disguise to their predators and a lure for the nectar-loving insects they eat.
The generous rains and constant warmth of the tropics create the steamy hothouse condiditons that help to promote such a luxuriance of growth and forms. Monsoon winds sweep the warm seas around Borneo, bringing as much as 200 inches of rainfall to the island each year. Rain is the lifeblood of the forest, and even in the driest months, few weeks pass without showers--or the tension and release of a storm.
It begins with a rumble like distant drums. The skies darken and inside the forest, it feels like nightfall. You hear the rain before it arrives. It sounds like a great ocean wave is approaching, and if you’re near a clearing, you might see a broad gauze curtain sweeping toward you across the forest. It pummels the canopy and streams to the forest floor. It teems down on the rivers with a thunderous beat, and turns steep trails into rushing waterways. The rain falls with an ever-increasing intensity and noise, rising in roaring surges of sound like an orchestra building to a feverish finale. Then suddenly it slows and stops. Sunlight beams down on the canopy. The forest drips, gleaming with moisture, and the world seems at once breathless and renewed.
On a bough high above the forest floor, two eyes bulge up. With a hop, a big frog lands on top of the branch and looks down at the crisscrossing network of greenery below. One hundred feet down, raindrops from the leaves of small saplings are still plinking into a pool. It’s a wallow created by a rhino, whose regular visits there to roll in the mud keep it a sump of shallow water. In a subtle way, the life of the frog perched high the canopy is bound to the habits of the lumbering gray rhino that lives far below: The heavy rains that soak the forest are quickly absorbed, and permanent standing water is scarce. The frog is a female, and though she spends most of her life up in the trees, she needs to lay her eggs in a foam nest overhanging still water, where her tadpoles will drop in and grow into frogs. When she’s ready to breed, she and her mate must journey down from the canopy to a pool on the forest floor, and that time is now. The male is already there. Far below her, he sits by the wallow and sings. She looks down, inches forward--and leaps. Her feet snap open like fans, and on huge outstretched webs connecting each finger and toe, she flies. Freefalling like a tiny parachute, she glides in a graceful, slow-curving spiral, down through the dizzying heights of the forest to the wallow--and lands on a broad leaf with a plop.
She is known as a Wallace’s flying frog, for the great 19th-century naturalist who first described her, and her astonishing aerial ability is believed to be linked to the unusual architecture of the Bornean forest. Unlike those of the Amazon and Africa, the rain forest canopy in Borneo is uneven; it rises and falls in rolling waves, with huge emergents poking up like islands. Beneath the canopy, the trees have fewer vines and lianas twining among them, and travel between levels of the forest or across the canopy layers is not as smooth for the creatures of Borneo as for those of other rain forests. To get where she needs to go, the frog flies--and she is not alone. One of the singularly amazing features of the Bornean forest is the wild array of mammals--and even reptiles--that have adapted to the forest’s structure with gliding flight. There are giant flying squirrels and flying lemurs known as colugos who spread huge elastic membranes connecting their legs to soar like dark kites between trees. There are flying lizards with bright red-and-yellow-patterned wings on their sides, flying geckoes that spread sucker-tipped webbed feet and skin flaps tucked under their bellies to sail between boughs, and perhaps most remarkable of all--flying snakes, who flatten their ribs and extend narrow folds of skin along the length of their bodies to swim through the air in fast-squiggling S-curves, drifting down through the layers of the forest.
The wind rustles the canopy, and a leaf twirls down to the forest floor. Within six weeks’ time, it will have returned to the canopy--decayed, broken down and reabsorbed as nutrients taken up by the sprawling roots of the great trees. One of the surprising twists of the rain forest’s richness is the poverty of the soil that anchors such a giant kingdom of life: Ninety-five percent of the organic nutrients of the Bornean forest are above ground, in the forest itself. The showers of leaves, animal droppings, blossoms and fruits that steadily rain down from the canopy layers are recycled many tens of times faster than in temperate forests; otherwise, their nutrients would be flushed away by the rains.
The forest floor is the musty workplace of the great decomposers and recyclers of the rain forest--fungi and bacteria, beetles and millipedes, streaming chains of ants and termites--and if you hike into the forest after an evening shower, some of them reveal their works in wondrous ways. Wait until dusk, when the six-o’clock cicadas begin to whine and geckoes bark from the trees; watch until darkness has risen like black fog from the floor of the forest to the sky. Enter the forest with a torch, alone and silent, then stand motionless and turn off the light. Beneath your feet and all through the undergrowth, the ground twinkles with chips of silver. It seems you are standing on a fallen drapery of phosphorescent lace. You might think it is moonlight filtering down through the canopy leaves, but if you pass your hand over the ground, it casts no shadow. The sparkling chips are luminescent fungi, and their weird light shines from the leaves and twigs on which they are feeding. Underground, fungi spread fine threads like roots, penetrating organic debris and slowly breaking it down. Especially after a good rain, their fruiting bodies appear--mushrooms and toadstools and others shaped in the bizarre forms of undersea tree corals, hairy orange cups or delicate snow-white veils. Nearby on a rotting log, a fresh cluster of mushrooms sprouts up--and glows fluorescent green, casting an eerie nimbus like pale neon. Chemicals in certain fungi make them gleam in the dark--some with a light so bright that you can carry them as a faint torch in the forest. Their luminescence may be a beacon to the beetles and other creatures of the night who consume them--and spread their spores through the forest.
By morning the green mushrooms have disappeared; a lone beetle creeps down the old log. The leaf litter below rustles, and a tiny pointed nose pokes up. A furry brown creature rushes over the log and the beetle is gone, carried off in a skittering zip through the leaves. The shadowy form is a treeshrew, a small mammal that looks like a fluffy-tailed squirrel with a long conical snout, black glass-button eyes and naked ears like a little monkey’s that lay flat against its head. Its name is misleading: Treeshrews are not purely arboreal, nor are they strictly insectivorous like shrews--or even members of the same family. They are classed in their own separate order, and in appearance and behavior, they are considered to resemble the primitive mammals that first arose and spread widely around the world during the dinosaur age, more than 100 million years ago. Today treeshrews are found only in the forests of Southeast Asia, and the headquarters for most of their 15 species is Borneo.
Treeshrews are among the many little-observed animals that help make the rain forest tick. Like squirrels, bats, civets and other small mammals, they play a key role in dispersing the seeds of the Bornean forest--but their movements are so swift and secretive that at best, they are only glimpsed. Though you might not catch the eye of the female who raced off with the beetle, you can sense her presence by a musky scent. Often in the forest you smell creatures you never see. The air inside is so humid and still that the odors of animals and the fragrances of fruits and blossoms linger in unseen clouds, and sometimes you seem to pass through spheres of scent that let you know who may be near--or attracted to come soon. The little treeshrew leaves a trail of scent where she goes, marking her territory, and if you could follow her crazed paths through the forest, you would see that once every other morning, she slips off at first light to one particular tree. Each time, she takes a new route, jumping between different saplings to make her approach. Fifteen feet up, she pauses on a bough by the tree, silent and motionless--then jumps into a hole in the trunk. Inside lie two newborn treeshrews, nestled in a bedding of leaves. For a few minutes, the babies nurse eagerly, swelling into fat balls full of milk. Then the mother climbs out and springs off--not to return for two days. Her system of maternal care is unusual, especially among mammals, but it may help to ensure success for her young. Until they are a month old and able to venture out from the nest, the baby treeshrews are helpless and utterly vulnerable: Their mother’s constant presence at the nest site might attract predators against which she could not defend them. So she sneaks inside, nurses them generously and fast, and leaves. In her absence, the young ones’ survival seems to rest on immobility and silence--and one other simple defense: While in the nest, the baby treeshrews have no scent.
Like most animals of the Bornean forest, the treeshrew is solitary, and although she weighs less than eight ounces, she logs the daily equivalent of a marathon--running for as much as ten hours a day over a relatively huge territory of several acres, just to find what she needs to survive. Her solitariness and hard work point to a paradox of what seems so fruitful and beneficent an environment. For both flora and fauna of the rain forest, common species are rare, and rare species common. The forest holds immense varieties of plants and animals, but most are widely scattered: Few plants occur in large stands; few animals live in big flocks or herds. A tree species that clusters in groves might be vulnerable to attack by insects or disease; at the same time, an animal must often travel far to locate, for instance, an individual fruiting tree whose food would not be sufficient to support a large group.
Competition in the forest is intense--for space, light, water, food--and, among plants, for pollinators and disperers of seeds. Many plants have developed specialized relationships with other species: The intricate designs of most orchid blossoms serve to fit hand-in-glove with specific insect pollinators; some trees produce fabulous blooms and cascades of fruits directly from their trunks to accommodate feeders and pollinators that inhabit the understory layers; and certain species of shrubs known as “ant plants” exude secretions that nourish private armies of ants who live in hollow chambers inside their stems--and ferociously defend the plants against other insects that might destroy them. But of all the myraid floral forms that find expression in the Bornean forest, one stands forth as the most outrageous of all--the incredible flower known as Rafflesia.
From a distance, a Rafflesia in full bloom looks like a brilliant red-and-white spaceship that just touched down on the forest floor. From a huge opening at the center of the blossom, five gigantic petals fan out--spanning a width that can exceed three feet. It is the largest flower in the world. Up close, the flower is even more bizarre: Inside the central cavity, the walls are polka-dotted and hairy, and from the bottom rises a peculiar forest of rubbery red columns, whose function remains unknown. The petals are thick and leathery to the touch--colored in a garish crimson-orange and often nubbled with bright white spots--and amid the browning leaves and debris of the forest floor, the entire flower looks so flamboyant and excessively overdesigned that it seems like a science fiction creation.
The 16 species of Rafflesia are native to the Southeast Asian region, and many are unique to Borneo--and extremely rare. Their requirements for survival are both exacting and mysterious. Rafflesia is actually a parasite, and the structural simplicity of the plant itself makes the flower seem all the more spectacular. The plant body consists solely of tiny filaments, like a fungus, that live only inside one particular vine,Tetrastigma, an unremarkable-looking member of the grape family. No one knows how Rafflesia’s seeds germinate and grow; it first appears as a thimble-sized brown bud on the grape vine that over a year’s time, steadily swells. In the biggest species, it expands to the size of a soccer ball, until it looks like a great blackened head of cabbage. Then, on some unknown cue, the black bracts split, and the petals unfold like gigantic frilled red lips around the gaping mouth of the flower. If it’s nearby, you can usually find your way to a blooming Rafflesia--even in the thick tangle of the forest floor. Just after opening, most Rafflesia blossoms send forth an odor as tremendous as the flower itself. The smell is like rotting flesh, and it is presumed to be a lure to the carrion flies that buzz in and out of the blossom for days--and pollinate the flower. Then, within a few days after opening, the blossom withers and collapses in a dark slimy mass. After that, its propagation hangs on a slim network of events: Only if the flower was a female fertilized by pollen carried from a male blossom that opened nearby at exactly the same time, will the Rafflesia produce a fruit full of seeds, and until recently, no one knew how they were dispersed. Researchers speculated that it might be a small animal, perhaps a nibbler that snuffles around in the understory and could inadvertently transport the seeds to the right place on the grape vine. Early one morning, from a blind set up near a ripe Rafflesia fruit, scientists observed a small dark creature climb into the fruit to feed: It was a treeshrew, and it ate for several minutes, then scittered off--the top of its nose covered in pulp.
One place where Rafflesia still thrives is on the lower slopes of Mount Kinabalu, the massive peak that rises like a glorious mountain island within the island of Borneo itself. All across northern Borneo, Kinabalu draws the eye; its jagged rock pinnacles even resemble the crown that it is to the island, and sometimes heavy wreaths of clouds so completely encircle the base of Kinabalu that is seems to float alone in the sky. The illusion befits the mountain: Kinabalu is a separate world, both linked to the tropical forests from which it rises and unique unto itself. From the lowland rain forests that wrap the base of the mountain to the 13,000-foot heights of the summit plateau, the slopes of Kinabalu are layered with distinct zones of life--floral kingdoms that change with each increase in altitude. Above the high tide line of the lowland rain forests, at about 4,000 feet, more than half of the plants on the mountain are Kinabalu’s own--found nowhere else in the world.
Climbing the mountain is an Alice-in-Wonderland experience, as you hike up through awesome colonnades of lowland dipterocarps into a cooler montane zone of smaller trees--oaks and chestnuts, myrtles and laurels--their branches decked with sprays of orchids. Of Borneo’s more than 3,000 orchid species--10 percent of the world’s total--more than 1,200 varieties grow on Kinabalu, from colorful necklace orchids that cascade in scented floral chains from the trees to tall sprays of elegant slippers and dainty jewel orchids hidden along rocky banks. Higher up, in the cloud forest, you climb through thick stands of bamboos and tree ferns that glisten with moisture combed from the clouds, then up to groves of stunted trees whose gnarled boughs are spongy with mosses and laden more thickly with even tinier orchids.
Above 8,000 feet, the trees grow ever thinner and smaller, and the soil is so exceedingly poor that few species can survive the twin rigors of cold and lack of nutrients. But here one of Kinabalu’s most celebrated families of plants has moved into an impoverished ecological niche--and flourished. They are known as the pitcher plants, and they have adapted to the harsh conditions with one of the most curious features of the plant kingdom: As they grow, some of their leaf tips uncurl and swell into long bulbous hollows with flaps that pop open on top--like old-fashioned water pitchers with hinged lids. In different species, the pitchers assume a wild array of shapes, from the wasp-waisted Low’s pitcher colored in lime green with a flaring burgundy mouth, to the gigantic Rajah, whose dark crimson urn can hold more than a quart of liquid. They dangle from boughs, swaying in the wind, and nestle along the steep slopes, like displays of painted pottery in an artist’s studio window. But the pitchers are a deadly lure: Under their rims, they secrete a tempting nectar that attracts insects who climb in, slip into a pool of digestive liquid--and dissolve, supplying the pitchers with nutrients that are lacking in the soil but that the plants are believed to need to survive. Their lids may prevent the pitchers from collecting moisture that would dilute their digestive fluids, but eventually, as they age, their lids curl back, and the pitchers slowly fill with rain; some animals come to drink from old pitchers, and if you look inside you may see the larvae of freshly-hatched insects, a cluster of snail’s eggs clinging just under the rim--or a tiny black frog, peeping to call a mate to the pitcher’s pool.
Beyond the pitcher-plant zone, the trees and shrubs steadily shrink to knee-height-- and lower. Great banks of clouds rush up the slopes; the winds gust hard, stinging with mist. At 11,000 feet, you pass the treeline, and 2,000 feet up the steep naked rock cap of the mountain spreads the summit plateau, a broad plain of granite cracked and peeled by ice and heat, and ringed with a dozen magnificent spires. If you climb to the summit of Kinabalu at sunrise, before the morning clouds build up to engulf the mountain, you can see westward to the pale blue mirror of the South China Sea, and look south across ridge after ridge of lowland rain forests below, as far as the eye can see. But the view is different from what a climber would have seen even 30 years ago. More people are settled in the valleys below; in the clearing season, you can see tall columns of smoke rising from the fields they are burning. Tiny red lines wind through the forested hills beyond, and if you could glide down and fly over the canopy like a hornbill, you could follow trucks rumbling down the red dirt roads, their trailers piled high with giant logs.
The face of Boreno is changing fast. The dipterocarp trees that form the great pillars of the forest grow tall and straight; their trunks are patched with resins that help them resist infection, and their wood is fine-grained and hard. These qualities make them the most commercially valuable tropical hardwoods in Southeast Asia, and throughout Borneo, they are being rapidly logged. The greatest concentrations of dipterocarps are in the lowland rain forests, where they comprise 90 percent of the large trees. The sale of their timber fuels the economies of Malaysian and Indonesian Borneo, and most of the island’s lowland dipterocarps have been, or are scheduled to be, logged. The majority of the cutting is selective--few forests are clear-cut--but the impact is more complex than the mere removal of the largest trees. Critics say that the act of felling and hauling often destroys swaths of surrounding forest, and that the presence of logging operations, in many places, disrupts local communities and their traditional use of the forest. Others point out that the logging roads that vein the forest offer easy access for hunters and poachers--and open new lands to clearing by settlers. While studies have shown that many mammals and birds can survive in carefully managed logged forests--and a few actually benefit from the changes--others have requirements too precise to survive logging’s effects. For the many plants and animals that only live in virgin forest--and the countless creatures whose intricate associations with other species form the forest’s grand interlocking web of life--a tree falls, and their world goes with it.
But a climber standing atop Mount Kinabalu would not be able to see other significant changes of the past 30 years. In the forests and hills of northern Borneo that spread below the mountain are lands that look as they have for many generations past. Most of the land visible from the summit of the mountain is part of the Malaysian state of Sabah, and since 1964, when a first park was established around Kinabalu, more areas have been designated for protection. Southwest of Kinabalu stretches the long spine of the Crocker Range, an entire mountain chain that is now a national park. To the east, a vital habitat along the huge Kinabatangan River has been proposed as a park to protect the rare proboscis monkeys that live in the mangrove-and-palm forests along its shores--a population that may represent the best chance of survival for a primate species that is unique to Borneo. On an especially clear day on Kinabalu, you might even see far to the southeast, to a region of lowland rain forest known as the Danum Valley Conservation Area. Covering 170 square miles, it encompasses the catchment basin of an interior stream, the Danum. It is a precious piece of the forest. Though it is small in relation to the size of the island, Danum Valley is the largest protected area of lowland rain forest in all of Borneo, and it holds a sample of the wealth of one of the richest natural kingdoms on earth, from rhinos and leaf monkeys, rare argus pheasants and otter civets to tiny treeshrews and flying frogs--even the tarsier and the small green katydid.
At dawn, the morning mist rises like steam from the huge lowland trees along the banks of the Danum: The forest is breathing. By early evening, the rain forest seems to exhale the very darkness it holds within, and far away to the northwest, when the last light gilds the highest rocks of Kinabalu, the blackness in the lowlands is already complete. Deep in the forest where the katydid lives, the insects are screaming. A family of flying squirrels glides the night skies across the river from the tall tree where they sleep in the day, and farther down in the dense understory, the little tarsier has just awakened. His eyes open wide and round to drink in the secret motions of the darkness. He leaps between saplings and freezes, muscles tensed: He’s hungry tonight. Every feature of his being is designed for the nighttime hunt--powerful legs to jump, sucker pads on his fingers and toes for clinging, huge radar ears to detect the slightest sound--but it’s his eyes that are truly extraordinary: They are 150 times bigger in relation to his size than are ours. He spins his head fast--a full 180 degrees--and fixes his stare on something below. The green katydid inches forward from the midrib of her leaf, directly into his sight line. The tarsier springs, and this time he doesn’t miss. In a blink in the darkness, she is gone. But hidden in the leaf litter below, her eggs are nearly ready to hatch.
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