24 EarthLines March 2016

The howling alerts you that something is coming. When it begins to rain in the lowland rainforests of Central America, the jungles of popular

imagination, howler monkeys send up the alarm, hooting crescendos, then wrapping themselves into dark, tight, miserable monkey-sized balls and moving not a bit until the rain is good and done. Parrots will talk endlessly about it. But parrots will talk about anything, almost anytime.

You rarely see rain coming in a tropical rainforest. Walking by a light gap, a place where a canopy tree has fallen and left a hole where once was vibrant life, you may look up and see the amorphous mass of clouds become thicker, the sky less blue. It looks like rain, but visuals often lie. Water can hide in such clouds for hours. In that much time, the clouds themselves have likely moved on.

In these forests, the first intimation of rain is the sound. The leaves are being slapped. For minutes after the rain becomes audible, there is no water on the forest floor. It filters slowly through a canopy both thick and high. Still dry, you hear it first, then begin

to feel it, and long after it stops falling from the sky it continues to fall from the canopy onto the ground. Puddles form on the clay surface of the forest floor, then slowly seep out of view.

One of the predominant sensations of being in such a forest is of water everywhere, as if you are forever approaching a vast, warm, but silent waterfall. On a night without rain, shining a beam of light up, you see water droplets flying through the air, seemingly suspended and moving … and yet, there is no sensation that water is falling on you. Water is all over, but it’s not actually raining. Moving through, it feels amazingly fluid. The ambient heat makes all of your body parts seem ready to melt. It’s not heavy, as people think. Walking is hard because of the mud, not because of the air. You don’t have to push through anything, but move at all and within minutes you will be covered in sweat. And that is a freedom, because trying to stay clean and dry in the rainforest is like driving your new car before it gets its first scratch. Walk just a bit and you first develop a sheen of sweat, then rivulets stream down inside your shirt, and soon enough everything

jUNgLE WET heaTher heying

Monkey tree-frog, Yasuní National Park © Geoff Gallice

EarthLines 25Issue 14

you are wearing is soaked through. Once that happens, you realize that the rain, if it comes, will be a relief.

~As a biologist who moves between latitudes, I observe obvious differences in biota – strangler figs and monkeys versus doug firs and chickadees. But the abiotic truths of the tropics – the processes of the non-living world – are just as different from those of the temperate zone as are the flora and fauna. At the equator, there are twelve hour days, and twelve hour nights, all year long. At the equator, you can not gauge the time of year by when the sun sets. It does not change.

In the tropics, there are also no marked swings of temperature between day and night – no long periods of light when the sun beats down interminably and things become very, very hot, nor any long hours of darkness where the cold settles in. Each tropical day is matched with the respite of a similarly long, cooling night. It is also true that the angle at which the sun’s rays hit the surface of the Earth is more direct, and therefore more intense, the closer to the equator you get. Like the round beam of a flashlight becoming elliptic and larger as you angle it away, so too is the sun’s energy spread across more area the farther from the equator you are. Light and heat spread and scatter before they get to us. Thus: hot tropical days even though they are always the same length.

Although there are barely any seasons based on daylength or on temperature in the tropics, there are many places with seasons based on rainfall. There are dry coastal tropical forests, which have distinct wet and dry seasons, trees that lose their leaves, obvious mating seasons, as the frogs posture and fight or the birds engage in song and dance. Climb away from the coast, get to any significant altitude, and the rain is both more likely to hang suspended, in cloud forests, and more likely to fall, when it does, seasonally. Move away from the centre – from the equator or from sea level, latitudinally or altitudinally – and abiotic forces converge on one another.

Even in lowland tropical rainforest, where it seems at first glance to be simply wet all the time, there are nonetheless predictable cycles of rain – times when it rains, yes, and then times when the heavens open, and it really, truly rains. Biologists talk imprecisely of those lowland rainforests as the ‘aseasonal’ tropics. But the truth is that like many occupants of the forest, the seasons here are good at camouflage.

~Once, early in my days in grad school, I was in a lowland rainforest in Costa Rica, in Sarapiquí, when the rainy season slid in behind our backs. Bret – then my boyfriend, now my husband – and I had finished our field work for the day, and wanted to go for a swim in the river. The mountains to our South fed the river, and it had been raining in those mountains. We knew

that, the way you might know that it had been raining at the beach, and are glad you aren’t there.

Walking across the high bridge to the accessible bank of the river, where a lovely sand beach had been our swimming spot for weeks, a local man we didn’t know began talking to us, trying to slow us down. Our Spanish wasn’t very good, but we did our best. While visitors in other countries, we would tend to talk to people who wanted to talk, but sometimes people will keep you for a long time, just chatting. We wanted to swim.

‘It’s been raining in the mountains,’ he said. He looked at us meaningfully.

‘Yes, true,’ we replied, not sure what else to say. He reached out to us, gestured upstream. We were not understanding, he seemed to imply.

‘It’s been raining up there,’ he said again. We looked, imagined rain in the distant landscape.

‘Much rain,’ we agreed. This, at least, was something our poor Spanish allowed us to say with assurance.

‘Wait,’ he said, putting his hand up, palm facing us, in a universal gesture. We stood there, looking between him, the planks and metal of the bridge, the surface of the water far below. ‘Look,’ he added then, pointing to the water.

It had begun to change. It was darker, now, with eddies where before there had been smooth flow. There were branches in it, and the water was moving faster every second. Now it rose visibly, two feet, four feet, eight – still below the level of the bridge we were standing on, but not by much. A giant log swept down, got sucked into a nascent whirlpool, and shot out downstream, many feet into the air. Then another. We should have gotten off that bridge, all three of us, but we stood rapt, watching, unmoving. The beach that we were going to was obliterated, the rate of flow so fast no swimmer could have survived it. Had this man not stopped us, delayed us in our descent to the river bank, we would almost certainly have drowned.

And then, the water changed again. The river smoothed, the eddies disappeared. It stopped rising, then began, much more slowly, to drop. No longer a raging vortex, it was still muddy and filled with forest detritus, and its flow was fast and strong, but it seemed predictable now. Like it would follow rules and expectations.

The man who had saved our lives nodded, said good-bye, and began to walk away. We didn’t even know his name. We had nothing to offer, nothing on us but the clothes we were wearing. Bret called him back, gave him the shirt off his back. We offered words of gratitude. He was appreciative. And then he was gone.

Later that evening, our professor at the time, he told us – people go to the rainforest terrified of snakes and spiders and predators, but it’s the water that will get you. Keep your eye on the water, and you will likely be just fine.

~Those times when it really, truly rains in the ‘aseasonal’

26 EarthLines March 2016

tropics often mark the change of season, and the moment tends to feel eerie and charged. In advance of it, for days, or even weeks, there may be suggestions of rain, but no rain. The promise of wet relief, and then … more sweat. Before the first big rain, many of the animals go still – only cicadas still keeping time during the day, frogs continuing the pulse at night.

The forests of the Tiputini Biological Station, in the Ecuadoran Amazon, are as aseasonal as they get. Tiputini is practically on the equator, very far inland on all sides, protected from weather created by oceanic winds and current. But there is a distinct start to the rainy season there, too.

In February of 2014, I took twenty American

another long, lean one that spews noise and fumes for the last few hours down the Río Tiputini, until we arrive at the station, our home for two weeks. There are no roads, no permanent human habitation except the station. While in graduate school, studying poison frogs, I had lived for many months in a tent in Northeastern Madagascar, showering in a waterfall, tracking time with the moon and tides. In some ways, Tiputini feels even more remote.

Landing at Tiputini that February, it was hot. But it always feels hot in tropical forests, especially when you have just arrived. You get acclimated. Usually.

~

undergraduates to Tiputini. Getting there from Quito takes a full day: first an hour’s flight over the Andes, then a few hours in a long, thin boat down the Río Napo. That ride ends in a military checkpoint, followed by a bone-rattling open-air bus ride through increasingly dense forest, and finally to the border of Yasuní National Park, the great jewel of the Ecuadoran Amazon, and by some accounts, the most biodiverse place on Earth. From that border, one last vehicle change, replete with the hauling of gear and provisions into the final boat,

Our first morning there, I go with a section of the class to a small lake, a rarity in the Amazon basin. In times past the entire basin was a vast inland lake, but it has long since become a land of rivers snaking through jungle. In some parts of the Amazon the rivers rise and flood reliably for months every year. Only the tops of the tree are above water, and you can boat through at canopy level, eye to eye with boas and monkeys that have been relegated to the treetops.

On this lake there is a canoe, and our guide, José,

Yellow-spotted river turtle, Yasuní National Park © Geoff Gallice

EarthLines 27Issue 14

paddles us out on it. In the bright equatorial light, we see sac-winged bats roosting on dead sticks emerging from the water. We see scores of hoatzin, improbable birds that provide direct visual evidence that yes, birds are dinosaurs. Hoatzin are large and ugly, ungainly in flight, and they cluster in spiny palms that form islands in the lake. We see a potoo, another improbable bird, mostly because, even six feet from it, with an unobstructed view of it on its perch, it is quite likely that you will not see it. Even if there are five of you, and you yourself have spent years in tropical forests looking for and at animals, and your guide is saying ‘I’ve pointed the canoe directly at it, it’s right in front of you’ there is a good chance that still, you won’t see it. And then, suddenly, you will. A nocturnal bird that roosts in perfect camouflage on snags, once you see it you think – ah, right, there it is. But then a giant fish flops out of the water, or you think you saw a caiman, or a cacique flies by, and when you look back to where the potoo was and in fact still is – again you can’t find it. They are that good.

But for all the dinosaurs and bats and caiman, the primary experience of being on the lake at this moment, before the rains start, is one of shimmering heat. We come off the lake glistening, slightly woozy, gabbling. Walking the couple of miles back to the station for lunch, it dawns on me: I am hot in a way that is not usual, where I come from. I am hot at my

core. Heat-drunk – more common than punch-drunk, in my non-punched experience – and more transient and deeply enjoyable than drink-drunk. For very few, this is daily life, everyday experience. But for me, and for those I have brought here, this is outside of what can be described easily. The air comes in swells despite the lack of wind. Insects and frogs call and buzz and shout, and their voices converge on the harmonics of the rainforest. The sound and suspended water seem to move through solid mass and air at the same rate, in a wave.

Later, the heat still pulsing, the air aquiver, a different section of the class and I ascend the canopy tower. The tower is a 120-foot-tall metal frame of stairs and scaffold, bolted to a giant emergent Ceiba tree, which itself has fig trees growing out the top of it. Every ten steps or so we turn 180 degrees, climb more, turn, climb, turn. At first, the vertigo is palpable. We are climbing a sparse, swaying metal structure deep in the Amazon. In places there are rays of sun beaming down like searchlights; in others the deep velvet green of the jungle is as dark as dusk. As we go higher, the sway intensifies, but the vertigo, oddly, diminishes. Climb, turn, climb, turn.

We climb amid woolly monkeys. The monkey troop is enormous, seemingly infinite. They keep coming in from the southwest, circling the tower in both directions, circling us, and we stop to watch the show.

Raining on the Río Tiputini, Yasuní National Park © Bret Weinstein

We are all, people and woollies alike, at least 70 feet up. The woollies traveling counter-clockwise around us arrive at a gap of six feet between two fig trees. Every single adult monkey who has navigated the tower in that direction makes the leap, but they have diverse methods. Some creep out to the edge of the branch they’re on, and leap from a static position. Most take it at a slight run, and land with a strong grip and a big bounce on the next tree over. One male misses his target, and plummets briefly before grabbing a branch lower down. Then comes a mother with a baby on her back, his four paws holding her tight, his tail twined around the base of hers. Then they’re off, running, and she leaps. She makes it, the baby bouncing perilously on arrival, and they continue into the heart of the tree. Baby climbs off, grabs something – a leaf, or an insect – and clambers back on Mom side-saddle, looking at us through half-closed eyes.

Standing at the top, on the canopy platform, we see birds – so many birds. Macaws and parrotlets, always chattering. Riotously colored tanagers, and some more subtly plumed, one lovely little one taking a bath in the axil of a large bromeliad. A lizard, a cresty-headed anole, captures a mantis and slowly, slowly, works it into his mouth. Howlers shout from far away. All this, and a view stretching across an endless forest, barely undulating into forever, the horizon a fuzzy line of green meeting hot white sky. The heat is otherworldly. There are a few brief moments of wind, then distant thunder. Such promise. But this kind of thunder, I learn, usually signals rain somewhere else. And no rain comes.

~A few days later; still no rain. Two students and I go to a salt lick with a blind built nearby. The lick is just a mud flat in the forest, where minerals collect, but the jungle dwellers know. First, one peccary arrives. Then ten. Then another twenty, ultimately at least fifty, probably more. Snorting and groaning in the mud. Every sixth one a juvenile. Three times they spook, and all run for the hills, funneling themselves up through a narrow passage on the far side of the mud flat. Slowly, after a minute or two, they come back, oozing back down the slope.

A few days after that I go back, alone, and nearly fall asleep in the blind, lulled by the heat and the buzzing of the cicadas. No peccaries. Half dozing, I wake to see a brocket deer come silently in to the lick, eat mud, then leave, as silently as it had come. Later, still from the blind, I watch an anole through binoculars, showing off his dewlap, doing push-ups, for nobody I could find. The air presses in, full of water, but still no rain.

Back at my cabin, a thunder crash, close in now. Is this the kind of thunder that means that rain will come here, rather than there? Heat envelops, a prickly background thrum pulsing forward into constant consciousness. Then the sound of a frog I have not heard before – braaahh

braaahh braaahh – loud in the near distance. Otherwise, forest small-talk – distant titi monkeys, parrots, other frogs. And then: another tremendous thunder break. Momentarily afterwards – silence. And then: back to braaaahh braaaahh braaaahh and forest small-talk. It is so damned hot.

~Finally, one day after lunch, I know it will happen. I confirm it with Diego. He is both the station manager and a researcher, and has lived here many years now. ‘It’s coming today, isn’t it?’ That’s all I need to say. Yes, he nods. It’s coming.

I can smell it, and feel it, coming. Ozone and buzzy-electric and that yellow-grey pall before a Midwestern thunderstorm, tingeing everything, even under the canopy, just a little. It is all of these things. But tell people who have never experienced it before that it’s now, it is coming, and they will tend to agree placidly and go back to whatever they were doing, because, well, yes, this is a rainforest, and it probably will rain, won’t it? Everyone knows what rain is.

No no no, I tell my students, no, you don’t understand – the rainy season is upon us. It’s happening. They nod distractedly at me and go back to reading about the rainforest, from the comfort of the lab.

When it really, truly rains in a lowland tropical rainforest, there is no replacement for being out in it. To sit inside under a corrugated metal roof when it hits, that is one loud thing; living inside a drum, it sounds like it must be hail. To sit outside but still protected, under a roof on a porch – well, you look through a screen of water, and the world grays out, the monkeys hunker down, even the leaves look sorrowful, muted green in a vertical wet world. But to go out into it or, better yet, to be out in the forest when it comes on, is to experience something else entirely.

A few fat drops and then: torrents. Trails turn into streams and then into pools, solid walls of water all around, cascading down slopes, yes, but also just pouring from the sky. It is all you can hear. It floods the senses – it is a cloud of shattering noise, bright cracks of branches falling, a river rising as you watch. The caiman on the river banks shift ever higher, resting with just their toes in the water, looking like logs. Your rubber boots fill in real time, water sloshing over the sides as you slog about. And you can fill your lungs, you can breathe deeply now that the spell is broken, but cannot share the joy with words, because nothing can be heard above the season. It has announced itself, roaring.

~The moment of first big jungle rain is a bit like the rare moment of rain in a desert – many organisms seize on it, for if they miss this opportunity to synchronize their activities, it will disappear.

28 EarthLines March 2016

hEAThER hEYINg is a professor of evolutionary biology at The Evergreen State College in Olympia, WA. Her Ph.D. work on the behavior and life history of poison frogs in Madagascar was groundbreaking, earning a distinguished dissertation award at the University of Michigan. In the book Antipode, Dr. Heying described her adventures as a graduate student working to reveal the hidden struggles and sex lives of frogs in an untamed place, on the far side of the world. This winter, Heather and her husband are with their two children and thirty undergraduates in the wilds of Ecuador, experiencing the mystery of neotropical diversity first hand.

gEOFF gALLICE is a tropical biologist whose scientific research focuses on the ecology and evolution of butterflies. In particular, he is interested in the clearwing butterflies, a group whose biology is fascinating, and which serves as a model for diverse studies in ecology and evolution in the tropics. He is also active in applied conservation research, including the impacts of road building on biodiversity and sustainable development in the Amazon rainforest.

EarthLines 29Issue 14

Some canopy trees burst into flower. Aelates emerge. Aelates, winged termites looking for a new life, a short life, emerge during breaks in the downpour, looking to make a new nest. But if they come out too early, or take too long, and the rain comes again, their wings become plastered to leaves, they drown in puddles, they drag their plump little dewinged bodies down trees, where gekkos and tanagers make snacks of them. The termites emerge en masse, looking for love for one brief moment. A jungle dweller who doesn’t pay attention to the rain risks an early death, or a life with no sex.

And now the rains, normally clocklike even in these ‘aseasonal’ forests, are getting less predictable. One year the rains come early; another year, they never end. How to synchronize blooming, or mating, when the clock is erratic?

Some of the rainforest emerges with the rain, but much of life there assiduously avoids the rains, or at least, avoids being out and visible when they happen. At a different salt lick, a wall of clay on the banks of the Río Tiputini, parrots go to klatsch. They are reliably there, early in the mornings, upwards of 150 of them at a time: blue-headed, mealy, orange-cheeked parrots, more. They meet and eat clay and talk and agree to meet again, tomorrow, same time same place. Weather

depending, of course. The parrots have a lot to say, but even they won’t klatsch in the rain. r

Parrots at a clay lick in Anangu, Yasuní National Park © Geoff Gallice