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Lifting the Green Veil
Photographs and text by Christian Ziegler

Rainforests are fantastic places, so full of magic they seem unreal. Life is everywhere, overwhelming us with the colors, shapes, sounds, and smells of exuberant nature. Rainforests are also very subtle places. Many animals are quiet and hide from visitors. It takes a long time to become aware of even a few of the countless creatures you are walking among. But if you close your eyes, you can feel their vibrant, if elusive, presence.

Howler monkey
Although howler monkeys' (Aloutta palliata) canines look fierce, they eat mostly vegetable matter.

The forest excels at concealing its treasures, challenging, and sometimes frustrating, a photographer like me. There may be a rustling in the leaf litter, the buzzing of an insect, a snake slithering into the ocean of green, a faint sweet smell hinting of a flush of flowers 100 feet above. You often perceive these events too late to get a glimpse, far less a good look, at the mysterious creatures responsible for them; they may be too high up in the leafy canopy, or too well camouflaged from sight. But then, in rare single moments, magic happens. A bird flits by and comes to rest, the sun shines on just the right spot to illuminate it, and you can see it, even snap a photo or two, before the scene starts to fall apart again. The forest opens its windows only briefly and rarely to share a secret with an observer.

Cicada
This colorful cicada has just emerged from its larval skin.

I’ve looked through these windows to photograph the rainforest of Barro Colorado Island for A Magic Web: The Forest of Barro Colorado Island. In a former life, Barro Colorado Island (BCI) was the top of a large hill in central Panama. Then, during the construction of the Panama Canal between 1911 and 1914, the Chagres River was dammed. Rising waters crept up the hill, leaving the hilltop isolated to form the largest island in the artificial body of water now known as Lake Gatun.

Covered with lush rainforest, the island has been studied and protected since the 1920s. In 1923, BCI was designated a sanctuary for the study of the tropical nature of the Canal Zone, becoming one of the first biological reserves in the New World. Since then, BCI has emerged as the most intensively studied area in the tropics of the Americas and, indeed, of the world. In 1946, the Smithsonian Institution assumed the management of Barro Colorado, and it became the seed from which the Smithsonian Tropical Research Institute (STRI) would develop, beginning in 1966. Today, BCI remains STRI’s main research station. A small campus in the rainforest, the station boasts housing for up to 60 scientists, modern lab facilities, and high-speed Internet. These amenities, coupled with a lively intellectual atmosphere, attract scientists from around the globe, making the island a mecca for tropical ecologists.

Red-Eyed Tree Frog Eggs
Red-eyed tree frogs (Agalychnis calladryas) glue their egg clutches to the undersides of leaves.

Positioned at the crossroads of two continents and two oceans, Barro Colorado is home to stunning biological diversity: 1,316 plant species, 381 bird species, and 102 mammal species have been recorded, while the number of insects is so great that it remains unknown. These thousands and thousands of different organisms, unique forms of life on Earth, each play a role in a vivid and complex web that makes the forest ecosystem function as a whole. But most of the living activity in the web goes on secretly and quietly, hidden behind a thick green curtain of vegetation or concealed by its miniature scale.

A microcosm of the web can be found in each square meter of forest leaf litter, where tens of thousands of springtails and mites feed on decaying plant matter and the fungi that grow on it, and vicious predators—large spiders or centipedes and sometimes more then a dozen species of ants—in turn feed on the arthropods. Seemingly small in scope, this so-called brown food web is essential for the cycling of nutrients in a tropical rainforest.

At a more human-size scale, mammals and other larger creatures play out their various roles as predator or prey or both. Ocelots eat sloths, for instance, and sloths eat leaves. To a plant, an animal may be a predator, and BCI is rich in leaf, seed, and fruit eaters. A bat called Artibeus jamaicensis, or the fruit vampire, is the most common bat species on BCI and loves fig fruits. But this is one of 20 bat species that dotes on fig fruits, which are available year round, and each likely has its own way to take advantage of them. Larger bats eat larger fruits, for instance. Such a diverse set of fruit-eaters—and there are other species that feast on figs as well—is not possible in a temperate zone, where fruit is seasonally available, accounting in part for the tropics’ greater species diversity.

Bat
The common fruit bat (Artibeus jamaicensis), shown here eating a fig, is the most common bat on Barro Colorado Island.

With diverse and abundant predators, prey have evolved amazing defenses. Katydids in the genus Mimetica—for mimic—exhibit near-perfect camouflage. Their color, shape, and texture imitate the leaves they rest on with incredible precision. But katydids are not just concealment artists. Some of them are specialized herbivores that prey on a single species or genus of plants. Specialized herbivorous insects help maintain tree diversity by preventing any given plant species from reaching high densities. On the other hand, the wide dispersion of the members of the tree species helps trees to hide from their specialized predators.

For every animal and plant I meet, I know that many other species—it might be dozens, hundreds, or even thousands—stay hidden. Each has a story to tell, sometimes bizarre and almost unbelievable, always interesting and fascinating, waiting for us to listen to it.

My goal as a photographer was to lift the green curtain of Barro Colorado for brief moments, to reveal the layers of the forest, to unravel its complex ecology, and to convey its beauty. This unparalleled habitat deserves our attention and protection.

—A Magic Web: The Tropical Forest of Barro Colorado Island, by Christian Ziegler and Egbert Giles Leigh (ISBN 0195143280), was published by Oxford University Press in 2002. Visit the website at A Magic Webwww.amagicweb.com.

ZooGoer 33(1) 2004. Copyright 2004 Friends of the National Zoo.
All rights reserved.

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