Teeming Life in Gabon's Rainforest
by Francisco Dallmeier, Alfonso
Alonso, Patrick Campbell, and Michelle Lee
It’s 5:00 a.m. We have already finished a quick breakfast and are beginning a long day in the field. We move out from camp along winding trails, laden with the supplies of modern-day scientists: binoculars, global-positioning system units, waterproofed notebooks, and such. We also carry with us the respect that people have acquired for this region over thousands of years. This is elephant, gorilla, leopard, and crocodile country. This is Gabon’s tropical rainforest—primeval jungle, an environment that sustains thousands of species, including Homo sapiens, and some that are dangerous to humans. It must be entered with care.
Specifically, this is Gabon’s Gamba Complex, more than 11,000 square kilometers (4,247 square miles) of tropical rainforest bordering the Atlantic Ocean and extending inland up to 100 kilometers (62 miles). This region boasts an incredible mosaic of habitat types that includes beach and sand dunes, littoral forest, mangrove forest, freshwater swamp, lowland seasonally flooded forest, upland nonflooded forest, open grassland, and extensive lagoons and lakes adjacent to the ocean. Further inland, expansive tracts of upland forest are sometimes dissected by lowland, seasonally flooded forest along rivers and larger streams. The entire area may represent a transition zone between the Guineo-Congolian tropical forest zones and savanna ecosystems to the south. That makes the Gamba Complex extremely important habitat for numerous resident and migratory species.
As part of the Smithsonian National Zoo’s Monitoring and Assessment of Biodiversity Program, we are privileged to head up a team of more than a dozen Smithsonian and international scientists, along with Gabonese researchers and “parataxonomists,” in an exciting multi-year biodiversity research and conservation project. We are documenting for the first time ever the rich variety of species and habitats—the biodiversity—of this region in west central Africa.
Scientists usually speak of biodiversity at several levels. Those interested in a single species might look at genetic variability within that species or the diversity of populations of that species. At a larger scale, biologists may catalog the number of different species found in a habitat type, known as species richness, or the different habitat types in an area. All of these studies contribute to biodiversity research, and the results provide useful information to manage and conserve the species or habitats in question.
Postage stamps issued by Gabon in 2004 celebrate
the nation's biodiversity. These stamps illustrate an
attitude shift from
the past—partly due to Smithsonian
efforts. The stamps below, issued in 1993, depict
a variety of animal traps.
In areas like west central Africa, where little research has been done, we started our work at the larger scale. Thus, we are attempting to describe habitat types and assess the different species found in those habitats in the Gamba Complex. The information we are gathering characterizes the area’s habitat types and documents the distribution of species in the field.
This baseline information is essential to in-country resource managers as well as to scientists in zoos and other conservation settings working to conserve rare or endangered species. The more we know about natural habitats and the behavior of species in those habitats, the more we can do to conserve elephants, big cats, monkeys, chimpanzees, birds, reptiles, and other creatures that attract millions of curious visitors to the National Zoo and thousands of other zoos worldwide. That knowledge also helps us to create strategies for protecting imperiled species such as gorillas—both in the wild and in zoos—and helping their populations recover.
Most of our initial research in Gabon has revolved around the question: What species are here and how can we collaborate with governments, industry, and other organizations to promote long-term conservation of those species? Our international researchers are experts in taxonomy, the science of classifying organisms in an ordered system that indicates evolutionary relationships. And they are adept at biodiversity studies that record all organisms—from large, charismatic species to small, elusive ones—and open doors to more specific ecological questions such as: Which snakes are active at night? Where are groups of gorillas nesting? What does today’s forest structure tell us about its history? How do these factors interact?
We are currently working to answer these questions about the Gamba Complex, and it is important to do so. The complex overlays vast oil reserves that have been a major source of economic activity in Gabon for more than 40 years. We initiated a partnership with Shell Gabon, one of the main companies operating in the complex’s oil fields, to provide sound biodiversity baseline information and to work with company personnel to integrate research findings into decisions related to both ongoing and future development of oil fields. This partnership also includes disseminating these results to all stakeholders through consultation meetings, briefing papers, scientific and popular publications, and regular updates on websites. We anticipate that the work will continue over the long term as biodiversity monitoring activities are carried out in different parts of the complex.
So far, our teams of experts have finished baseline studies at five locations: Rabi, where oil fields are in operation; Toucan, a relatively untouched area where oil operations are just beginning and where we have the opportunity to conduct research in the early stages of development; Loango and Moukalaba-Doudou, two recently established national parks; and Gamba, where oil operations have been in place for 40 years and small towns exist. Our work takes place during what we call the dry and rainy seasons in this tropical forest, although to most of us in the United States both seasons would be considered rainy (and hot, and steamy).
We are amazed at the results so far. The vast storehouse of biodiversity in the Gamba Complex is exceeding our expectations, and the knowledge we are gaining should have a tremendous impact on the conservation of rare species in their natural habitats, as well as in living collections at zoos.
A Plethora of Plants
Our botanists have established 75 biodiversity research
plots, each 0.1 hectare in size (about one-quarter acre),
throughout Rabi, Toucan, Loango, and Moukalaba-Doudou.
In the plots, researchers record the size and type of
trees and enter these data into computers using software
developed especially for this type of work. These data
allow scientists to describe the various habitats by
composition (the most common species) and structure
(the relative size and distribution of the trees).
The vegetation team has assessed tree diversity in the plots scattered throughout the Gamba Complex. They recorded more than 7,000 trees, measuring five centimeters (about two inches) or more in diameter, of at least 300 different species. They also collected hundreds of specimens of fruits or flowers for the botanical collections of international herbaria, where the public can view many of them and where scientists will conduct more studies to discover any secrets the plants hold. Remember, many of the pharmaceuticals we use today had their origins in wild plants.
As Dr. Henri Bourobou-Bourobou of l’Herbier National du Gabon says, “The Gamba Complex is rich most likely because it is very remote and thus relatively untouched by logging and other extractive activities. The canopy averaged 40 meters [130 feet] in height with the big trees that characterize a mature community , including Coula edulis, Diogoa zenkeri, and Santiria trimera.” Chimpanzees use wooden clubs and stones to break open nuts of the Coula trees, sometimes called Gabon nut trees, to extract the edible kernel; other primates eat the fruits of the Santiria, also known as the African walnut.
Analyses of preliminary data from all sites describe a dynamic, old-growth forest where tree fall gaps are common. “This allows for a mix of both early and late successional species,” explains Bourobou-Bourobou. “Lianas are abundant everywhere, and along with early successional species, they are often indicators of disturbance. But we believe most disturbance in this forest environment is from natural causes. There is evidence of selective logging in only a few localized areas. When all of the tree species are eventually identified, we will be able to examine the spatial aspects of vegetation in the complex to gain insight about the dominant species. We can then relate that information to the resource needs of animals in the region and add to knowledge about any rare species that may be vulnerable to human activities.”
What's in the Water
The aquatics team studying fish in the complex expected
to record between 40 and 50 species, based on studies
in similar habitats elsewhere in Gabon. “We were
surprised and very pleased to find 70 species so far,”
enthuses Jean-Aimé Yoga of Gabon’s Institute
for Research and Forest Agronomy. “What this means
is that the Gamba Complex may well be a ‘hot spot’
for fish diversity.” Jean-Aimé and the
other members of the aquatics team spend hours encased
in high waders as they explore the lagoons, lakes, streams,
and rivers of the complex. Using large gill nets for
deep water, beach seines for shallow areas with sandy
or muddy substrate, dip nets for small creeks, and occasionally
a hook and line, they are building a solid baseline
of information. Their work at 27 different sampling
stations in the Mbari, Echira, and Rabi Rivers is the
first-ever fish survey conducted for these three river
systems.
The team recorded several interesting species, including Polycentropsis abbreviata, a rare leaf fish that stalks prey by camouflaging itself as a leaf floating in the water, and seven species of electric fishes in the family Mormyridae—two of which, it appears, may be new to science. The team explains that it is likely that another one or two specimens from other fish groups may also be new, but it will take more investigation to be certain.
New and Exciting Herps
In a search throughout the swamps and lowlands of the
complex, our team of herpetologists has recorded 159
different species. These include 75 elusive amphibians,
73 of which are frogs. Marius Burger, a leading South
African herpetologist, points out that “one of
the frogs has proved difficult to identify and may actually
be a new species. It’s a reddish brown creature
with a white stripe outlined in black running from the
snout to the hind leg on each side. We know that it
is in the genus Hyperolius, commonly called
reed frogs, but so far we haven’t seen it described
in the literature.”
The reptilian findings were equally impressive, among them 22 species of lizards and 46 species of snakes. The snakes include the spectacularly patterned rhinoceros viper (Bitis nasicornis), which sports a signature upturned “horn” at the end of its snout that gives it its name, and the beautifully colored arboreal green bush viper (Atheris squamiger), a patient predator that hangs upside down from branches at night and ambushes small rodents, lizards, and frogs.
The herpetologists also recorded three amphisbaenians (burrowing, snakelike reptiles) of a type previously known only from a single specimen described 96 years ago! And their finding of a large and healthy population of the slender-snout crocodile (Crocodylus cataphractus) is very important because this species has become severely imperiled through over-hunting and destruction of its habitat. The team produced rare footage when they videotaped the hatching of a crocodile egg found in a wetland nest as it emerged from the shell.
Combinations of traps that use 100-meter-long (328-foot) drift fences capture animals alive and unharmed. These passive capture devices—the animals basically follow along the fences until they fall into the traps, which are set in the ground—are very effective in sampling nocturnal species and secretive species that live in leaf litter.
Many biologists prefer to work quietly in the forest, but our team of herpetologists also takes great joy in bringing the forest to the public. They traveled 85 kilometers (52 miles) south from Rabi to Gamba, a town of about 8,000 people in the complex, to make four presentations on snakes: one for the general public, one for Shell security guards, and two for schoolchildren. The team carefully exhibited several live specimens so that people could see creatures they ordinarily would not encounter in the forest. “The school kids were surprisingly eager to pet the snakes,” Burger states, “but the adults showed a lot more reluctance.”
Birds in the Mist (Nets)
In all, we have recorded 316 different species of birds.
The total number of species known from those sites is
455, based on a survey conducted in 1992. We hope to
catch sight of the rest of the species in future work.
“We are particularly excited about species such
as the African gray parrot (Psittacus erithacus)
that we encountered,” says the Smithsonian’s
George Angehr, who heads up the bird team. “That
bird, like many other tropical birds, has experienced
declines because of the pet trade.”
This team uses lightweight mist nets to catch and release birds. The nets are strung between trees at various heights throughout different forest habitats. Vocalizations and opportunistic methods such as sightings are also used to record birds. The bird team members are often the earliest risers at the camps, walking out to open their nets and sit quietly as they listen for morning calls. The team found that 73 percent of the bird communities at the Rabi and Toucan sites are dominated by species that prefer interior forest habitats. Other birds seem to prefer regenerating forest or even sites that have been disturbed by logging. The highest capture rate was at Mbari near Rabi, a logged-over site where large numbers of yellow-whiskered greenbuls (Andropadus latirostris), greenish-brown birds with yellow beards, were attracted by an abundant berry crop on bushes that proliferate in the area.
One important question the bird team is addressing in its research is how birds react to disturbances, such as infrastructure for oil extraction. So far, we’ve seen varied responses. Some birds such as the brown illadopsis (Illadopsis fulvescens), which inhabits interior forest and whose habitat has been interrupted by a road, were flying back and forth defending territory on both sides. Other species in the same area were apparently nonplussed. We have seen flocks of great egrets (Egretta alba) flying around gas flares despite the heat, noise, and light. And the crowned eagle (Stephanoaetus coronatus), the largest eagle in Gabon and a species protected by Gabonese law, was a special sighting next to a new road.
“Bird activity is not strongly affected by roads and flares at this point,” Angehr notes, “and that is good news—for now. It will be important to monitor the area of the new road and determine if it creates access for logging and hunting.”
Magnificent Mammals
Our mammal team has recorded 42 medium and large mammal
species throughout the Gamba Complex. Among the most
frequently documented species are well-known animals
such as African elephants (Loxodonta africana),
lowland gorillas (Gorilla gorilla), chimpanzees
(Pan troglodytes), and African forest buffalos
(Syncerus caffer nanus). Less familiar species
include sitatungas (Tragelaphus spekei), large
antelopes that live only in muddy, swampy habitats;
putty-nosed (or white-nosed) guenons (Cercopithecus
nictitans), arboreal monkeys that live in groups;
and cat-like African civets (Civettictis civetta),
and servaline genets (Genetta servalina). It
is not uncommon for us to encounter elephants every
day as they go about their business; in fact, we see
five to ten or more on a typical evening. Despite heavy
rains, we consistently find tracks and feeding signs
of many other mammals that are more difficult to observe.
To document the activity of more elusive species, the mammal team used tripwire cameras baited with different types of lures, primarily scents, to attract animals for photographing. These olfactory lures are made from the scent glands of carnivores such as skunks, bobcats, and coyotes, which mark their territories with their scents. When an animal in the complex approaches a lure, the camera takes its picture. With this technique we’ve taken pictures of elephants, red-capped mangabey monkeys (Cercocebus torquatus), a leopard (Panthera pardus), and two species of forest antelope called duikers.
The mammal team also walked transects at a distance from roads during the day and night to observe evidence of passing animals. They looked for footprints, nests, scat, and, of course, for the animals themselves. Occasionally, they saw animals such as galagos—small, primarily nocturnal primates referred to as “bush babies,” which, while not rare, are seldom seen.
Raphaël Ngangui, a Gabonese field technician who works with the small and large mammal teams, noted that, during the dry season, “We revisited some of the same sites in the dry season that we had surveyed in March in the rainy season. We found evidence of some of the same major species, but not others. Obviously, climate differences have an effect on animal behavior and movement. Monkeys, for example, will move to find trees with fruit that matures in different seasons.”
Next Steps
This project has certainly captured the hearts of those
of us who are involved in the fieldwork, despite the
fact that it takes us away from our families and homes
for weeks at a time. We are in the midst of new discoveries
that may prove beneficial to people as well as to imperiled
species and habitats.
In the process, we are training more than a dozen Gabonese scientists and parataxonomists in well-tested, standardized, biodiversity research and data-management protocols. Open houses, lectures, and slide presentations in surrounding communities, and regular reports from the field will continue to inform scientists, governmental officials, Shell employees, local residents, and the public at large of our progress and results. For example, the Gabon Biodiversity Center, established in the fall of 2001, is proving to be a world-class facility to coordinate research and its applications for conservation, to process samples, and for training.
Over the next few years, our work in the Gamba Complex will continue to document the amazing biological diversity of this part of the world. We are particularly pleased that the Gabonese government has established a new national park system that encompasses nearly 11 percent of the country’s lands and waters. And in September 2002, the Smithsonian joined a U.S. delegation headed by Secretary of State Colin Powell that traveled to Gabon to formalize the Congo Basin Forest Partnership for biodiversity conservation and sustainable development.
This development infused new energy into our combined research, training, and communications effort. The Smithsonian/Shell partnership continues to produce high-quality biodiversity data and analyses that are generating necessary dialogues between industry, conservation organizations, governments, and local communities. We look forward to contributing more information and knowledge as a promising future for biodiversity in Gabon emerges.
—Francisco Dallmeier, Alfonso Alonso, Patrick Campbell, and Michelle Lee are with the Smithsonian Institution’s Monitoring and Assessment of Biodiversity (MAB) Program, a program of the National Zoo’s Department of Conservation Biology. MAB focuses on the broad goals of research and education and seeks to integrate science—especially conservation biology—with resource development projects around the world. In cooperation with governments, industry, and other research entities such as zoos, the program strives to conserve Earth’s storehouse of biodiversity and the potential that millions of species hold for future generations.
The Gabon Biodiversity Project described on these pages
is a collaboration of our program, Shell Gabon, Shell
Foundation’s Sustainable Energy Program, the Gabonese
government, and other national and international organizations.
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The book The Edge of Africa, featuring the photographs of Carlton Ward, Jr., and text by the authors of this article, can be purchased at the National Zoo Store.
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32(5) 2003. Copyright 2003 Friends of the National Zoo.
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