TROPICAL NIGHT


The tropics. Images of distant, foreboding lands covered in thick, impenetrable jungles of vegetation immediately come to mind. It has the flavor of mystery, danger, adventure, and even a little romance. Every time the word is mentioned in conversation, one can almost hear the wild calls of the forest creatures and see the eyes of thousands of animals peering at them between jumbles of leafy branches. In our minds, monkeys swing playfully through the vines overhead while snakes and small, furry creatures scatter under each footstep. But many people visit the rain forests of the world and return disappointed and unfulfilled, seemingly robbed of this magical experience. "How could this be?" they ask. "Where were all the fascinating and bizarre animals we've heard so much about?"

This experience is quite common among people who visit the tropics. They may have traveled hundreds or even thousands of miles to reach their destination, the great expanses of rain forest, to walk for hours with only the occasional sighting of a small lizard or the glimpse of a bird high overhead. The most common experience in a rain forest is one of prolific mud, endless sweating, and swarms of hungry mosquitos and horseflies. Many tourists return to their world exhausted, confused, and itching like mad. For them, the experience of the tropical rain forest is one to be avoided.

The solution for those of us traveling to these areas, who want to see the profusion of animals for which rain forests are renowned, is quite simple. Go out at night. You may not relish the thought of venturing into an unknown tangle of danger and the unexpected, and the thought of experiencing this same forbidden world in complete blackness may send chills up your spine or set your heart racing. But for the brave (and possibly a little foolhardy) it is a journey into the intriguing realm of the creatures that inhabit one of the most diverse ecosystems on Earth.

The animals of the rain forest are marvels of adaptation, particularly in camouflage. Even the most astute observer is hard-pressed to distinguish a well-camouflaged animal or insect amongst the confusion of leaves, branches, and vines. Even more so, many of the animals of the tropics avoid the day's heat altogether, retiring to underground lairs, piles of debris, or caverns in hollowed out logs and trees. Under these circumstances, it is no wonder that the average visitor to the rain forest comes away seeing very little.

But all this changes at sundown, when predator and prey alike come out in full view to hunt or forage for their meals, often coming down to the river's edge. Since color does not exist in a low-light environment, cryptic coloration is no longer useful in the darkness of the night. Many of the animals and insects leave the safety of their daytime retreats to wander out, oblivious to the threat of being seen. Grasshoppers and caterpillars crawl out from under leaves and palm fronds, no longer in danger of being spotted by hungry birds. Katydids, which may conform perfectly to a clump of green leaves in the daytime, perch on top of off-colored vegetation and branches, chirping and munching away. During the day, most butterflies flit by so rapidly that you can barely get a glimpse of their beautiful markings and colors. Identification is often an impossible task. At night, however, they perch upside-down under leaves and are very easy to observe close up. Most can even be picked up by hand and examined. It is a time for careful observation and a time for surprising encounters.

It may seem like a well-kept secret but a nighttime trip downriver through a rain forest can be one of life's most fascinating experiences. It is also a much more pleasurable experience than a trip during the day. With the coolness of the evening, you are not constantly sweating and if it is cool enough, you may not encounter any mosquitos or horseflies (except at dusk). You rarely need to put on insect repellant when venturing out at night and if you do so, you may only need to apply it to your face and hands. Paradoxically, insect repellant is of little use during the daytime when mosquitos are at their worst due to the continual flow of sweat, which simply washes any repellant away soon after you put it on.

The edge of day is also a time to encounter an abundance of wildlife. Dawn and dusk provide excellent opportunities for observing animals. Birdwatchers know that birds are most active in the early morning hours, particularly around sunrise. The noise of their calls and songs make them easier to locate and identify. Howler monkeys often roar from the trees overhead, announcing their territories. Their sounds can be heard for several miles and you may be awakened by them if you’re not a heavy sleeper. The males begin their low-pitched bellows, sometimes two to three hours before dawn, and are answered by males of neighboring troops. The forest resounds with a chorus of their booming voices and echoes, and if you are unfamiliar with the noise, it can fill you with a haunting sensation. Snakes and other reptiles emerge with the first rays of sunlight. They must raise their body temperatures before initiating other daily activities. As a result, most are quite sluggish and approachable as they lie in the warming radiance of the sun.

Sights

One of the benefits of going out in search of animals at night is that the light from your flashlight penetrates only a short distance into the forest, beyond which is unknown blackness. This is conducive to careful observation since it focuses your attention on a small area. You begin to notice details and hidden animals which you would have passed in daylight when your senses are overloaded with other visual inputs. Concentrating on a small patch of the forest or riverbank allows you to better explore the hidden nooks and crannies which would otherwise fade into the background of a daytime scene. Humans are naturally curious and when we can see far ahead and nothing in the immediate vicinity, we tend to forge on and not take the time to delve a little further.

Without fail, bats will swoop in and out of the beam of your flashlight, catching the myriad of moths and flying insects that are attracted to the light. You can feel the bats as they swish by your head, a rush of wind blowing on your face. It can be an unnerving experience as a bat appears from the darkness but never has one run into a person or made actual physical contact. You may be startled by their sudden arrival and mildly curse at them under your breath for appearing without fair warning, but soon you will grow accustomed to them and go on about your business, knowing they will collect the annoying moths and insects that flutter about in the glow of your flashlight. It is fairly common for the hovering bugs to fly haphazardly into your mouth or eyes so you may even welcome the unintended protection afforded by feeding bats. Besides, even though you might unintentionally swallow what may seem like dozens of the aggravating insects, you will never have to stop and spend five minutes spitting like mad, trying to dislodge a bat that had just flown into your mouth.

A flashlight can also be used to locate and "hold" other animals. During the day most mammals are inevitably aware of your presence long before you can reach them. In the night however, the wind dies and your scent cannot be detected well in advance. Without visual cues, it becomes much easier to surprise them if your approach is reasonably silent. The shine of the flashlight tends to freeze larger animals, similar to the effect headlights have on deer in the road. Since the animals of the rain forest are unfamiliar with bright light in the night, they do not relate the sudden appearance of "daylight" to any form of hostile presence and simply stare wide-eyed at its source, seemingly trying to discern what this bizarre occurrence is about. With this advantage, you may get the chance to observe a reclusive species you could never approach during daylight hours.

There are natural, but more subdued, sources of light in the tropical night. Hundreds of species of fireflies (compared to the fifty or so species in North America) flash their mating signals from all levels of the forest. Each species has its own flash pattern, a unique signal between male and female, announcing their whereabouts and availability to mate. Generally, their numbers within the confines of the trees are quite low but you may come upon large clearings in the forest where millions of them have congregated to display their nighttime beacons. As they perch atop the grasses in the open fields, it can look as if someone has meticulously strung countless blinking lights across each of the grass blades in some overblown display of Christmas spirit.

Other times you may surprised by small, constantly glowing lights that float down from the blackness of the forest canopy, hovering and bobbing like a helicopter looking for a place to land. The strange, luminous "landing lights" of a click beetle soon come to rest on a nearby branch of vegetation. Generally there are two glowing, yellow spots on the upper-side of the beetle's hard exoskeleton and a triangular, orange patch on the bottom. The yellow lights on top are continually displayed but the orange patch underneath is hidden between two plates below the head and is only exposed when the beetle is in flight.The function of these lights is still uncertain but may possibly be a form of mate attraction, similar to that used by fireflies. Natives and other local people have been known to collect the phosphorescent beetles, wearing them as necklaces and other forms of ornate jewelry.

On very dark, moonless nights it is possible to discern in the distance faintly glowing objects on the forest floor. Upon closer inspection the source of the weak light is found to be a bioluminescent fungus (basically, a glow-in-the-dark mushroom). The cap and stalk (or fruiting body) of several species of fungi can exhibit a faint, eerie glow; sometimes detectable up to twenty yards away. Other species produce light in their mycelium; the long, fibrous structures of fungi that are normally underground or unseen. Early explorers of the rain forest came back with tales of "glowing wood" and "logs of light", which are simply cases of bioluminescent mycelium growing in the bark of trees or in rotting logs.

Sounds

The most obvious change from the daytime environment when you enter the Amazon forest at night (other than the amount of light) is the "sound" of the forest. At dusk, a new symphony of noise begins, generally much louder than that of the daytime. When you first travel to the tropics, you may be looking forward to peaceful and relaxing evenings of sleep - away from the din of traffic and sirens of the States. You will soon discover that you are sadly mistaken, for the cacophony of chirps, squeaks, and croaks can be far worse than any night in downtown U.S.A. But like any city dweller, you should soon get accustomed to the constant background noise and upon your return, you may even find it hard to sleep without it.

Hundreds of species of crickets, grasshoppers, and katydids chirp their songs - some even singing in unison as they crescendo, then quiet, and then start again. During the rainy season, frogs come out to mate by the thousands - screeching their calls around newly-formed pools and streams. Each male tries to attract a mate by calling louder than the other males, resulting in a chorus that can be heard hundreds of yards away. If you are well-trained, you can even recognize each frog species solely by its call, exactly what the female must do while looking for a male. However, for a human, locating the source of the call is almost impossible. Our stereo ears are unable to pinpoint the direction or distance of the calling males. The calls seem to come from every direction and isolating a single one to follow from all the others is quite a formidable task. People often imagine the female frog wandering aimlessly through the leaf litter, looking for the source of her attracting racket, but somehow, they seem to manage to do so much better than us.

Some species of treefrogs call from inside rolled-up leaves which act as a bullhorn for their calls. These booming voices echo from all around and trying to locate a calling treefrog can be a maddening affair. Humans also tend to make noise unlike that of friendly beings as we rummage through the underbrush and as soon as you get close enough to possibly find the source of the call, the frog shuts up for awhile, until silence returns once again. This means in your quest to find it, you must search, stop, and wait for the next call. Search, stop, and wait. And the closer you get, the longer the wait between calls. Only with the greatest of patience and practice is it possible to locate calling frogs in the rain forest with some degree of success.

Other calls, resounding from the trees overhead, do not sound like a frog but more distinctly bird-like. When you shine your flashlight into the leaves above, two bright eyes among the branches glare back at you. The owner, a kinkajou, then turns away and disappears higher up into the vegetation. The kinkajou, also known as a "nightwalker" or "honey bear", is a tropical member of the raccoon family and spends its time in the trees feeding on insects, fruits and occasionally honey. Like the raccoon, it is primarily nocturnal, and only by following their unmistakable calls can you find one in the tangle of leaves of the canopy above.

Owls also call from the trees, and their outlines, along with those of bats, can be seen at dusk in open areas of the forest or alongside rivers as they swoop down in search of small rodents, insects, or reptiles. You may find yourself face-to-face with owls perched on branches of small trees alongside a trail. The feather markings of some owls form a mottled vertical pattern which matches the vertical tree bark pattern precisely. If you had passed them during mid-day, you probably would have walked by without noticing.



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Copyright © 1995 Dr. Nicholas B. Carter.
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