Stevenson Press 1998 - 2002
Stevenson Press published numerous books about the rainforests and other tropical habitats. At one time you were able to order them on this site.
Would you like to help save the rainforests and their inhabitants?
This is the questioned poised this site. Stevenson Press provides many good books to read, while several organizations concerned about the rainforests and other tropical habitats provide informative articles below.
This issue was important in 1998 and remains so today. The new owners of this domain have chosen to provide content from the site's 1996 - 2002 archived pages. Unfortunately the Stevenson Press books can no longer be purchased here.
Stevenson Press, Inc.
588 Sutter Street #112
San Francisco, CA 94102
An Introduction to Understanding the Tropical and Rainforests for Students and Teachers
This lisf of questions and answers most often asked by students as prepared by the Rainforest Action Network:
What is a rainforest?
A tropical rainforest consists of three layers of life: the canopy, the understory and the forest floor. The canopy is the treetops (160-220 feet, or 55-75 meters, tall!) which make up the rainforests' green ceiling. Most of the animals of the rainforest such as monkeys, birds, tree frogs and even snakes, live in the canopy. The understory is the young trees, ferns and shrubs that are under the canopy. Most plants in the understory never grow to adult size because the canopy blocks out most of the sunlight. Except for rotting vegetation which nourishes the thin tropical soil, the forest floor is almost bare. Large mammals, like jaguars and African gorillas, live on the forest floor.
Where are the tropical rainforests?
Tropical rainforests are located around the equator where temperatures stay 80 degrees Fahrenheit year round. Rainforests receive 160 to 400 inches (400 to 1,000 cm) of rain each year. The largest rainforests are in Brazil (South America), Zaire (Africa) and Indonesia (South East Asia). Other tropical rainforest places are in Hawaii and the islands of the Pacific and Caribbean.
Who are the indigenous people of the rainforest?
They are usually called Indians, or indigenous people. No one knows for sure how or when these original inhabitants of the rainforests got there. There are perhaps a thousand or more forest groups around the world -- many close to extinction! In 1900, Brazil had one million Indians. Today, there are fewer than 200,000 in the Amazon.
Why are the rainforests so important?
Rainforests help control the world's climate. In the rainforest, it rains a lot and is very hot. When it rains, the heat makes the rainwater evaporate back into the air. This means it's recycled. Rainwater in the Amazon can be recycled five to seven times. Half of rain in some rainforests come from evaporation. The clouds that cover the rainforests around the equator reflect the sun. This keeps the rainforest from getting too hot.
Rainforest canopies also absorb carbon dioxide, which is a gas in the atmosphere. When the rainforests are burned and cleared, the carbon is released. This makes the weather much hotter and is called the greenhouse effect.
What happens to a rainforest when the trees are chopped down?
About 80% of the rainforests nutrients comes from trees and plants. That leaves 20% of the nutrients in the soil. The nutrients from the leaves that fall are instantly recycled back into the plants and trees. When a rainforest is clear-cut, conditions change very quickly. The soil dries up in the sun. When it rains, it washes the soil away.
Won't a rainforest grow back?
Not with the diversity of plants and animals. Rainforest ecosystems have been developing for hundreds of millions of years and have species that only live there.
Clear-cut - to cut down all the trees in a part of a forest.
Climate - the usual weather conditions of a region throughout the year.
Developing country - a country where people work mainly at farming, mining or logging, not in industry.
Diversity - variety.
Developer - someone who buys land and increases the activity on it.
Deforestation - clearing land of trees by cutting or burning.
Ecosystem - all the living and non-living things in a certain area.
Equator - an imaginary line around the Earth that is an equal distance from the North and South Poles.
Evaporate - to change from a liquid into a gas, such as when water is boiled, it turns to steam.
Extinct - no longer in existence.
Endangered - when a population is so small, that it's at risk of becoming extinct.
Fertile - land where plants and forest can grow easily.
Greenhouse effect - the trapping of heat from the Sun within the Earth's atmosphere. The burning of fossil fuels creates gases that prevent heat from escaping into space. This makes the Earth hotter.
Hunter-gardeners - people who exist by growing their own food.
Hunter-gatherers - people who exist by hunting, fishing or searching for food in the wild.
Human rights - something that people should have simply because they exist.
Indigenous people - native, original inhabitants of a region.
Industrial country - a country where the majority of people work in manufacturing, like making cars from steel.
Logging - the business of cutting down trees and bringing them to sawmills.
Non-profit - a company that is established for a purpose other than for making money.
Nutrients - providing nourishment.
Species - a group of people, animals or plants that have many common characteristics or qualities.
Sustainable - using the forest in a way that does not harm it so it can be used in the future.
Toxins - a poison that is produced.
Vegetation - all the plants or plant life of a place.
World Bank - a special agency of the United Nations that makes loans to countries wanting economic help.
The Rainforest Fund Campaign
Would you like to visit a tropical forest and see everything you've read about here?
You can. If you live in the United States of America or Canada, the closest tropical forest you can visit located on Mexico's Yucatan Peninsula. Only a few hours from the resort of Cancun is a place called Punta Laguna. There you can walk through the tropical forest, see Spider Monkeys, visit the Maya people who live in the reserve and see for yourself, all accompanied by a guide who can answer all your questions. The great thing is that Cancun is an easy place to visit; there are convenient flights from all major cities in North America. And Punta Laguna a day trip from Cancun
Our presence in cyberspace is free to all but it is only made possible through the members of Mesoamerica Foundation.
We invite you to become a Member!
Yes, I want to join Mesoamerica Foundation's efforts to save the Maya cultural patrimony to humanity.
Ms. Libby Phipps, Memberships
Apartado Postal 343, Administracion 1
Merida, Yucatan, Mexico
About Mesoamerica Foundation's Maya World
Maya World is an electronic-magazine produced by Mesoamerica Foundation and is dedicated primarily to the dissemination of information about the archaeology, history, culture and societies of the Maya peoples of Yucatan, Chiapas, Guatemala and Belize.
Tropical Rainforest Animals and Native Peoples of Tropical Forests
by Susan Silber
1993 Rainforest Action Network
Part I: Tropical rainforest animals
Where can you find an antelope the size of a rabbit, a snake that can fly, or a spider that eats birds? All in tropical rainforests, of course!
Tropical rainforests are home to many of the strangest-looking and most beautiful, largest and smallest, most dangerous and least frightening, loudest and quietest animals on Earth. You've probably heard of some of them: jaguars, toucans, parrots, gorillas and tarantulas all make their homes in tropical rainforests. But have you ever heard of the aye-aye? Or the okapi? There are so many fascinating animals in tropical rainforests that millions haven't been named or even identified yet. In fact, about half of all the world's species live in tropical rainforests.
Why do more species of animals live in rainforests than other parts of the world?
Scientists believe that there is such a great diversity of animals because rainforests are the oldest ecosystem on earth. Some forests in Southeast Asia have been around for at least 100 million years ago, ever since dinosaurs roamed the Earth. During the Ice Ages, the last of which occurred about 10,000 years ago, the frozen areas of the North and South Poles spread over much of the earth, causing huge numbers of extinctions. But the giant freeze did not reach many tropical rainforests. Therefore, these plants and animals could continue to evolve, development into the most diverse and complex ecosystem on earth.
The nearly perfect conditions for life also help contribute to the great numbers of species. With temperatures constant at 75-80 degrees Fahrenheit the whole year, animals don't have to worry about freezing during cold winters or finding shade in the hot summers. They rarely have to search for water, as rain falls every day in tropical rainforests.
Some rainforest species have populations that number in the millions. Other species consist of only a few dozen individuals. Living in limited areas, most of these species are endemic, or found nowhere else on Earth. The maues marmoset, a species of monkey, wasn't discovered until recently. Its entire population lives within a few square miles in the Amazon rainforest. It is so small, it could sit in a person's hand!
Which type of rainforest species is the most numerous?
If you were to visit a rainforest, you probably wouldn't run into many jaguars or monkeys. The only living animals you could be sure to see are the millions of insects creeping and crawling around in every layer of the rainforest.
Scientists estimate that there are more than fifty million different species of invertebrates living in rainforests. One scientist found fifty different species of ants on a single tree in Peru! You would probably only need a few hours of poking around in a rainforest to find an insect unknown to science. You could even name it after yourself!
Insects aren't the most lovable creatures, but they are sometimes beautiful and always fascinating. Have you ever heard of an ant that farms? Or ants that act as security guards? Read on! Leaf-cutter, or parasol ants, can rightfully be called the world's first farmers. They climb trees up to 100-feet tall and cut out small pieces of leaves. They then carry these fragments, weighing as much as fifty times their body weight, back to their homes. Sometimes they must travel 200 feet, equal to an average person walking about 6 miles with 5,000 pounds on his or her back! The forest floor is converted into a maze of busy highways full of these moving leaf fragments.
These ants don't eat the leaves they have collected, but instead bury them underground. The combination of leaves and substances that the ants produce such as saliva allows a type of fungus to grow. This fungus is the only food that the ants need to eat.
Azteca ants live on the swollen thorn acacia tree, which offers the ants everything needed for survival--lodging, water and food for themselves and their young. In return, the ants protect the trees from predators. Whenever the ants feel something brush against the tree, they rush to fiercely fight the intruder. They also protect it from vines and other competing plants that would otherwise strangle it. As a result, nothing can grow near these trees. They are the only trees with a built-in alarm system!
How do all these species manage to live together without running out of food?
The constant search for food, water, sunlight and space is a 24-hour pushing and shoving match. With this fierce competition, you may be amazed that so many different species of animals can all live together. But this is actually the cause of the huge number of different species.
The main secret lies in the ability many animals to adapt to eating a specific plant or animal, which few other species are able to eat. Have you ever wondered, for instance, why toucans and parrots have such big beaks? These beaks give them a great advantage over other birds with smaller beaks. The fruits and nuts from many trees have evolved with a tough shell to protect them from predators. In turn, toucans and parrots developed large strong beaks, which serve as nutcrackers and provide them with many tasty meals.
Do animals ever help each other out?
Many animal species have developed relationships with each other that benefit both species. Birds and mammal species love to eat the tasty fruits provided by trees. Even fish in the Amazon River rely on fruits dropped from forest trees. In turn, the fruit trees depend upon these animals to eat their fruit, which helps them to spread their seeds to far-off parts of the forest.
In some cases both species are so dependent upon each other that if one becomes extinct, the other will as well. This nearly happened with trees on the now-extinct dodo bird. They once roamed Mauritius, a tropical island located in the Indian Ocean. They became extinct during the late 19th century when humans over-hunted them. The calvaria tree stopped sprouting seeds soon after. Scientists finally concluded that, for the seeds of the calvaria tree to sprout, they needed to first be digested by the dodo bird. By force-feeding the seeds to a domestic turkey, who digested the seeds the same way as the dodo birds, the trees were saved. Unfortunately, humans will not be able to save each species in this same way.
How do rainforest animals protect themselves?
Each species has evolved with its own set of unique adaptations, ways of helping them to survive. Every animal has the ability to protect itself from being someone's next meal. The following are just a few of these unique and often bizarre adaptations.
Camouflage. The coloring of some animals acts as protection from their predators. Insects play some of the best hide-and-go-seek in the forest. The "walking stick" is one such insect; it blends so well with the palm tree it calls home that no one would notice it unless it moved. Some butterflies, when they close their wings, look exactly like leaves. Camouflage also works in reverse, helping predators, such as boa constrictors, who sneak up on unsuspecting animals and surprise them.
Slow as a snail. The three-toed sloth is born with brown fur, but you would never know this by looking at it. The green algae that makes its home in the sloth's fur helps it to blend in with the tops of the trees, the canopy, where it makes its home. But green algae isn't the only thing living in a sloth's fur; it is literally "bugged" with a variety of insects -- 978 beetles were once found living on one sloth!
The sloth has other adaptations. Famous for its snail-like pace; it is one of the slowest-moving animals on earth. (It can even take up to a month to digest its food!) Although its tasty meat would make a good meal for jaguars and other predators, most do not notice the sloth as it hangs quietly in the trees, high up in the canopy.
Deadly creatures. Other animals want to announce their presence to the whole forest. Armed with dangerous poisons used in life-threatening situations, their bright colors warn predators to stay away.
The coral snake of the Amazon, with its brilliant red, yellow and black coloring, is recognized as one of the most beautiful snakes in the world. But don't admire its beauty too long; its deadly poison can kill within seconds.
The poison arrow frog also stands out with its brightly colored skin. Its skin produces some of the strongest natural poison in the world, which indigenous people often use for hunting purposes.
Another animal with no friends is the hoatzin. Often called the stinkbird, it produces a horrible smell to scare away potential predators.
Is it true that dozens of animal species a day become extinct in tropical rainforests?
An average of 35 species become extinct every day in the world's tropical rainforests. The forces of destruction such as logging, cattle ranching and over-population have all contributed to the loss of millions of acres of tropical rainforest. Animals and people alike lose their homes when trees are cut down. These animals are given no warning to move -- no time to pack their bags -- and most die when the forest is destroyed.
Many large animals such as leopards and apes need miles and miles of territory to roam and have a tough time surviving in smaller and fragmented habitats they are forced into by humans. In one day's work a bulldozer could destroy the habitat of the golden toad, whose entire population lives on one mountain in Costa Rica.
When rainforests are destroyed, animals living outside the tropics suffer as well. Songbirds, hummingbirds, warblers and thousands of North American birds spend their winters in rainforests, returning to the same location year after year. Fewer return each spring, as fewer make it through the winter because their habitat has been destroyed.
The cutting down of trees is not the only reason for species extinction. Thousands of monkeys and other primates are traded illegally on the international market each year, wanted for their fur, as pets, or for scientific research. Parrots and macaws have also become popular pets; buyers will pay up to $10,000 for one bird. Even a king of the jungle, the jaguar, is in danger of becoming extinct. Its fur is highly valued for use on coats and shoes.
Rivers have become both over-fished and polluted. Gill-nets now allows fishermen to kill huge amounts of fish at a time. They often use only the larger and more profitable fish, dumping the dead smaller fish and other animals such as dolphins back into the rivers.
Pollution from mining has killed fish populations in the mighty Amazon River. Many indigenous people, who have depended on these fish for centuries, have become sick from the poisoned fish.
Extinction happens naturally. Species like the dinosaurs and the saber-tooth tigers have died off from their failure to adapt to the changing environment. But nowadays humans are altering their habitats too quickly for them to adapt. Only in this modern day have so many species become extinct in such a short period of time.
Humans must share the Earth with all plants and animals; otherwise our dominance will result in the continued extinction of many species. It would be a sad world indeed without the beauty or the grace and power of the jaguar.
Part II: Native peoples of tropical forests
Who are indigenous people?
Tropical rainforests are bursting with life. Not only do millions of species of plants and animals live in rainforests, but many people also call the rainforest their home. In fact, indigenous, or native, people have lived in rainforests for thousands of years. In North and South America they were mistakenly named "Indians" by Christopher Columbus, who thought that he had landed in Indonesia, then called the East Indies.
In general, how do indigenous people live?
Although many indigenous people live much like we do, some still live as their ancestors did many years before them. These groups organize their daily lives differently than our culture. Everything they need to survive, from food to medicines to clothing, comes from the forest.
Food. Shifting cultivation is still practiced by those tribes who have access to a large amount of land. However, with the growing number of non-indigenous farmers and the shrinking rainforest, other tribes, especially in Indonesia and Africa, are now forced to remain in one area. The land becomes a wasteland after a few years of over-use, and cannot be used for future agriculture.
Education. Most indigenous children do not go to school like our children do. Instead, they learn about the forest around them from their parents and other people in their community. They are taught how to survive in the forest. They learn how to hunt and fish, which plants are useful as medicines or food. Some of these children know more about rainforests than scientists who have studied rainforests for many years!
What are some differences in indigenous cultures?
The group of societies known as Europeans includes such cultures as French, Spanish and German. Similarly, the broad group of indigenous peoples includes many distinct cultures, each with its own traditions. For instance, plantains (a type of banana) are a major food source for the Yanomani from the Amazon while the Penam of Borneo, in Southeast Asia, depend on the sago palm (a type of palm tree) for food and other uses.
Why is the land so important to indigenous people?
All indigenous people share their strong ties to the land. Because the rainforest is so important for their culture, they want to take care of it. They live what is called a sustainable existence, meaning they use the land without doing harm to the plants and animals that also call the rainforest their home. As a wise indigenous man once said, "The Earth is our historian, our educator, the provider of food, medicine, clothing and protection. She is the mother of our races."
Why are indigenous cultures in danger?
Indigenous peoples have been losing their lives and the land they live on ever since Europeans began colonizing 500 years ago. Most of them died from common European diseases which made indigenous people very sick because they had never had the diseases before. A disease such as the flue could possibly kill an indigenous person because he or she has not been exposed to this disease before. Many indigenous groups have also been killed by settlers wanting their land, or put to work as slaves to harvest the resources of the forest. Others were converted to Christianity by missionaries, who forced them to live like Europeans and give up their cultural traditions.
Until about forty years ago, the lack of roads prevented most outsiders from exploiting the rainforest. These roads, constructed for timber and oil companies, cattle ranchers and miners, have destroyed millions of acres of rainforests each year.
All of these practices force indigenous people off their land. Because they do not officially own it, governments and other outsiders do not recognize their rights to the land. They have no other choice but to move to different areas, sometimes even to the crowded cities. They often live in poverty because they have no skills useful for a city lifestyle and little knowledge about the culture. For example, they know more about gathering food from the forest than buy food from a store. Imagine being forced to move to a different country, where you knew nothing about the culture or language!
Are indigenous people fighting for their land?
Indigenous groups are beginning to fight for their land, most often through peaceful demonstrations. Such actions may cause them to be arrested or even to lose their lives, but they know that if they take no action, their land and culture could be lost forever. Kayapo Indians, for example, recently spoke to the United States Congress to protest the building of dams in the Amazon, and were arrested when they arrived back in Brazil, accused of being traitors to their own country. In Malaysia, the Penan have been arrested for blocking logging roads.
Many people living outside of rainforests want to help the indigenous peoples' cultures. They understand that indigenous people have much to teach us about rainforests. By working with these groups, we can learn important information about rainforests -- its ecology, medicinal plants, food and other products. It is crucial to realize that they have a right to practice their own lifestyle, and live upon the land where their ancestors have lived before them.
Saving the Tropical Rainforests of North America:
Conservation and Compatible Resource Use on Mexico's Yucatan Peninsula
an overview prepared by Pronatura Peninsula de Yucatan, A.C.
© 1996 Pronatura Peninsula de Yucatan
The natural heritage
Mexico's Yucatan Peninsula is blessed with a tremendous diversity of ecosystems, wildlife and wilderness areas. Its 700 miles of Gulf and Caribbean coastline frame vast expanses of well-preserved tropical forests. Freshwater marshlands more extensive than the Everglades in Florida mark its western boundary, and the world's second-longest barrier reef forms the eastern limit. These settings are home as well to one of Mesoamerica's most venerable cultures -- the Maya -- who conserve many of the traditions and beliefs of their ancestors. Man and nature have co-existed for millennia on the Yucatan Peninsula -- "the land of the pheasant and the deer." It is the challenge of our generation to ensure that such co-existence continues.
The Yucatan Peninsula is perhaps best known for its coastlines and beaches, which attract 2 million visitors a year. Other visitors include three species of endangered sea turtles, which come to the beaches to lay their eggs. The coastlines are fringed with brackish estuaries and shallow, hypersaline seas. This is where North America's only mainland flock of flamingos -- some 25,000 birds in all -- live and breed. Bordering the estuaries are largely unbroken mangrove forests that provide breeding and nursery grounds for countless crustaceans, fish, waterbirds and reptiles. Migrant birds, especially shorebirds, use the coast as a stopover point on their long, biannual migrations. The huge, scarcely studied freshwater wetlands of Campeche's Laguna de Terminos and the Caribbean coast's intricate coral reefs round out the Peninsula's biological bounty.
Most of the Yucatan Peninsula, however, is forest -- from dry tropical "thorn forests:" of the northwest corner to the lush, semi-evergreen rain forests of the south. Here, too, a wide range of rare and endangered species cling to a last stronghold: jaguars and ocelots, king vultures, tapirs, hawk-eagles, monkeys and ocellated turkeys. More than 1,500 plant species are known from the southern portion of the Peninsula alone, and research there is just beginning. Almost a third of the bird species in Yucatan's forests are migratory, including most of the neotropical migrant species whose supen population declines have caused worldwide alarm. All told, 147 species of vertebrates, excluding fish, are endemic to the Maya Forest region.
The justification for conserving Yucatan's natural heritage extends beyond the wildlife. Human populations have lived off Yucatan's natural bounty for thousands of years, fishing, logging, hunting, farming and gathering. Humans to this day use these natural resources, though population and development pressures have pushed some wildlife populations and even ecosystems to their breaking-point. A healthy, well-balanced environment in the Yucatan Peninsula is an irreplaceable asset for the people of the Peninsula and their future well-being.
Low population densities in much of the Peninsula have allowed large expanses of wilderness to be preserved in nearly pristine state. Harsh conditions in the seasonally dry interior and on the storm-battered coasts traditionally kept most humans from settling there. Nature prospered, but times have changed.
In recent decades, population has soared along the coast as migrants from the agricultural interior -- most of them fleeing from collapsing henequén, or sisal, industry -- have flocked there in search of subsistence employment. These migrants bring with them little knowledge of coastal resources: their use of them is generally immediate, desperate and unsustainable. Fish resources are already showing clear signs of depletion, and the new settlements have made few if any provisions for sewage treatment, trash disposal or urban planning. Commercial interests have also targeted much of the coast for development, primarily for tourism. Cancun, which did not exist 25 years ago, is now a city of 500,000 people. In the rush to develop, planning and caution were frequently disregarded, and the result has been an increasingly fragmented wetlands system under direct assault by human activities.
In the vast forested regions of the interior, settlers from the over-crowded parts of Mexico are awarded land grants or simply encouraged to become squatters. Villages appear overnight; entire regions have been settled in a few short years. Settlers from other regions arrive with agricultural and ranching techniques inappropriate to the extreme climate and poor soils of the Peninsula. Large areas were cleared -- some by campesinos, or rural residents, some by official development projects, and almost always to nobody's long-term benefit. Communities already established must seek new ways to reap benefit from the available natural resources. Continued expansion and misuse of resources is unsustainable and almost certainly a recipe for environmental collapse and human adversity.
The challenge facing conservationists is to provide the Peninsula's residents with sustainable techniques for using their forests, fields and wetlands. By working with communities to develop compatible economic alternatives, conservationists on the Yucatan Peninsula act on a guiding principle: Human communities, to prosper, need healthy ecosystems.
Two conservation programs
- Yucatan Coast Conservation Program. Conservationists have focused their coastal activities on the conservation of two Special Biosphere Reserves: Celestun and Ria Lagartos, the two key habitats for continental Caribbean flamingos and an extremely important area for neotropical bird migrants, ducks and shorebirds. Their primary mission is to preserve wetlands ecosystems important for their biodiversity and economic value, especially to the region's fisheries. Ria Lagartos has a management plan, which conservationists assist the Mexican government in implementing. The Mexican government has recently commissioned Pronatura to coordinate various social, scientific and governmental organizations in the development of a management plan for Celestun.
In turn, Pronatura, in conjunction with The Nature Conservancy and the U.S. Agency for International Development, has since 1991 spearheaded the "Parks in Peril" Program at both Celestun and Ria Lagartos. Through this program conservationists have provided logistic support to the reserves, purchasing and equipping reserve headquarters, setting up a radio communications net, placing informative and restrictive signs and providing provisions, field equipment and vehicles for park rangers. Conservationists have also organized environmental education activities with boat tour guides and youth groups to involve local residents in park protection, and have promoted sustainable resource use through several aquaculture activities in conjunction with local fishing cooperatives. A multi-year sea turtle survey program has been used to involve youth and adults in endangered species conservation.
For the remainder of the century, conservationists have developed a coastal conservation project will:
- stop the encroachment of cattle ranches on the reserves by introducing holistic ranching methods;
- promote economic self-sufficiency of the reserves by investing in basic ecotourism infrastructure, including a Visitors Center at Celestun; and
- expand community development work with local residents to boost participation in the production and compatible use of coastal resources.
- Calakmul Biosphere Reserve. Calakmul Biosphere Reserve is Mexico's largest protected area of tropical evergreen forest -- more than a million-and-a-half acres of habitat for countless species of plants, animals, insects and resident and migratory birds. Conservationists are now working with residents of the reserve and surrounding areas to implement sound land-use practices, including: sustainable honey production; agroforestry and reforestation of disturbed areas; organic agriculture and soil conservation techniques; and environmental education programs that stress the benefits of the sustainable use of natural resources.
In the short time since we've begun these projects, conservationists have enjoyed the strong support of the Mexican government and the organization of local ejidos, or communal farms, for initial pilot projects. Many of these projects are now being expanded to include more villages and ejidos.
Since 1993, conservationists, principally Pronatura, have been responsible for the basic geographic, economic and social surveys of the reserve. In apition, ongoing studies of the mammals, birds, fish, reptiles and flora of the region ap daily to our knowledge of the reserve's rich and complex ecosystems, and help pinpoint the zones within the reserve that are in most urgent need of protection. In 1993, Pronatura signed an agreement with the state and federal governments to participate directly in the management of this vast protected area.
In the coming years, conservationists will continue installing basic management infrastructure for the protection of Calakmul's "core" areas and will expand its work with local communities to assure the compatible development of neighboring "buffer" zones. Calakmul, after all, is the largest rain forest park in the whole of North America.
Strategies for saving the neotropical forests of North America
In Mexico, conservationists have embarked on a set of strategies designed to save the threatened tropical habitats of the region. These strategies consists of:
- Protected-area management. Conservationists provide technical assistance, resources and planning skills to the managers of the selected reserves, including support for the Reserves' guards. Pronatura, for instance, was one of the first private groups in Mexico to sign agreements with state and federal government agencies for the co-management of protected areas. Today conservationists also participate on management and planning committees for five apitional protected areas on the Peninsula.
- Community development. Conservationist staff members work with local communities and community organizations to identify, test, develop and disseminate sustainable uses for the reserves' natural resources. Better living standards for reserve-are residents pays off in a strong local commitment to protect the reserves. The program is expanding to provide business planning for rural enterprises through the marketing of reserve products, such as honey.
- Environmental education. Conservationists work to promote a greater awareness in the general population and especially among reserve residents of the value of nature and the importance of protecting it. By training teachers, producing educational materials and using media outlets, the program seeks to involve local communities in the protection of the reserves.
- Research and monitoring. Behind all conservation work on the Peninsula is a solid tradition of applied scientific research. Researchers focus on providing decision-makers with the information they need to make informed decisions about resource-use, species protection and economic development. In apition, and advanced monitoring and geographical information system enables conservationists to monitor ecosystem health and potential threats to it in the three reserves and surrounding areas. Work to date in the coastal areas has focused on wetland hydrology, migratory birds, marine turtles, and flamingo studies. At Calakmul Biosphere Reserve, basic surveys and mapping of human and wildlife populations have provided a foundation for sound management.
Would you like to help save the rainforests?
P. O. Box 140681
Coral Gables, Florida 33114-0681
Saving the Pyramids:
Acid Rain Accelerates the Destruction of the Maya Ruins in Mexico's Yucatan Peninsula and Central America
by John Noble Wilford
© 1996 Mesoamerica Foundation
To understand the urgency to save the Maya ruins located in Mexico and Central America, which are often collectively referred to as "Mesoamerica," what follows is the text of a news report published by The New York Times on August 8, 1989.
Acid rain falling on the Yucatan peninsula and much of southern Mexico is fast bringing destruction to the temples, colorful murals and haunting megaliths of the ancient Maya civilization, art historians and archeologists say.
Evidence of widespread damage to the Maya ruins is the most telling example yet that acid rain, which can blight forests and lakes as well as damage stone structures, is not confined to the world's northern industrial regions. It is a clear warning signal, environmental experts say, that this form of "chemical weathering" is threatening the millions of acres of tropical rain forests in southern Mexico and Central America.
Alarming amounts of acid rain were also reported earlier this year over central Africa, caused by pollutants from the burning of thousands of square of grasslands. The Maya fallout, by contrast, is attributed to pollutants from oil refineries and tourist buses.
The damage to Maya treasures is greatest, the experts say, in the temples at Palenque, where paint is flaking off by the handsful and stucco surfaces and stone inscriptions are corroding and crumbling. A black crust of acid deposit coats one wall of the Great Ball Court at Chichén Itzá. Archeological treasures at Cobá, Chicanna, Uxmal and other sites are also showing acid's devastating effects.
"We've been struggling with this problem since the mid-1970's, and it's getting worse," said Dr. Richard E. W. Adams, an archeologist at the University of Texas at San Antonio, who specializes in Maya research.
"I have seen a marked difference in the buildings and statues" over the last decade, said Dr. Dorie Reents-Budet, curator of pre-Columbian art at Duke University. "It's happening at all the sites."
Dr. Seymour Lewin, a professor of chemistry at New York University and an authority on stone preservation, said acid rain's ruinous attack on statues and archeological sites is "becoming a worldwide phenomenon," from the Parthenon and Michelangelo's David to the Taj Mahal and the hundreds of stone monuments on the battleground at Gettysburg.
In a three-year study supported by the National Geographic Society, Dr. Merle Greene Robertson, an art historian and director of the Pre-Columbian Art Research Institute in San Francisco, not only documented that "the sculpture and architecture of the Maya civilization are being destroyed by acidic precipitation," but warned that surrounding forests "are now subject to increasing levels of acidic rainfall."
Although damage to the forests is not apparent yet, Dr. Robertson recommended that the governments of Mexico, Guatemala, Belize, Honduras and Cuba as well as international organizations "commence studies on the effects of acidic precipitation on the tropical environments of Mesoamerica."
Damage to tombstones
Dr. Robertson said in a recently completed report on the study, that researchers used meteorological observations to trace the source of the Yucatán's acid rain mainly to emissions from uncapped Mexican oil wells and oilfield smokestacks near Coatzacoalcos and Ciudad del Carmen on the Gulf of Mexico. The wells are operated by Pemex, the Government-owned petroleum company. The nearest oil field is 75 miles from Palenque and 250 miles from Chichén Itzá.
Dr. Lewin had earlier called attention to the effects of oil refinery emissions on monumental stone in a study of limestone monuments in an 18th century Jewish cemetery on the island of Curaçao, off Venezuela. Comparing plaster casts taken of the tombstone inscriptions with the condition of actual stones after years of exposure to refinery vapors, Dr. Lewin found "an enormous difference, with the inscriptions practically gone."
The burning of petroleum produces oxides of nitrogen and sulfur that rise into the upper atmosphere. There they are borne by wind and undergo chemical reactions with sunlight and moisture. After a few days, the sulfuric acid and nitric acid particles fall as acid rain or as dry acidic debris. The acid rain eats into the stone surfaces at once. The dry particles settle into crevices, ledges and molding, and the damage they create come later, when rain comes in contact with the deposits and creates corrosive chemical reactions.
Besides its immediate damage, Dr. Lewin said, acid rain acts as "an opening wedge," creating cracks and pits that make the stone increasingly vulnerable to damage from ordinary water seepage and invasion by decay-causing microorganisms. Most of the ordinary wear and tear on the Maya structures, which have survived 700 to 1,500 years, has come from exposure to moisture, mold, bacteria and roots of vegetation in the humid jungle. Acid rain is believed to be accelerating these processes.
One of the ugliest manifestations of the accumulation of acid fallout takes the form of "black scab." Even if the deposits are removed with extreme care, archeologists said, underlying paint and stucco usually flake off in the process.
Vivid colors now covered
Dr. Robertson, who has studied Maya art for years, used pictures taken in the early 1970's to document the rapid deterioration that has occurred at several archeological sites. Some of the stucco walls that used to be painted red or blue, she said, are now virtually white from the acid-caused flaking. Moldings and inscriptions are severely eroded.
At Cobá, she said, the interior of the Temple of the Paintings once was decorated with murals in vivid colors, but now the walls are "in such a devastated condition that there is very little one can see inside this shrine except the black scab, bacteria and mold that covers everything."
A stone carving at Palenque was cleaned of black scab in the early 1980's Dr. Robertson said, and is already being recoated.
Although the Mexican government has blamed much of the damage on volcanic releases from El Chichón, which erupted in 1984, Dr. Robertson said in an interview that photographic evidence indicted that the volcanic fallout, though severe, was a relatively minor contributor to the erosion of the ruins. Archeologists said the only cause for greater damage than acid rain is the rampant vandalism at Maya sites.
Charles Gallenkamp, an archeologist in Albuquerque, N.M., and coordinator of a recent exhibition of Maya artifacts on a nationwide tour, said: "The problem is beyond dispute. It's only a question of what can be done about it. Mexicans are very sensitive about protecting their archeological patrimony. But this brings you up against some very powerful commercial interests at a time when the country is having all kinds of economic troubles."
"Politically explosive" issue
Louis E. V. Nevaer, editor of Mesoamerica, an English language quarterly journal published in Mérida, said acid rain was a "politically explosive" issue in Mexico.
He said the Government had officially acknowledged acid rain as a problem only in the Mexico City area. With the reports of damage to Maya sculpture and buildings, however, Mexico will be open to criticism from international ecological and archeological groups and perhaps from neighboring countries vulnerable to the fallout.
"It's risky to be critical of Pemex in Mexico," Mr. Nevaer said in an interview. "Pemex is the country's No. 1 earner of hard currency."
The journal Mr. Nevaer edits is published by Mesoamerica Foundation, an organization that arranges for the exchange of scholars in economics, politics, arts and sciences between the United States and Mexico. Dr. Robertson's report was published by the foundation.
Exhaust of tour buses
Not all the damage is traceable to the Pemex oilfields. Dr. Robertson said the rapid deterioration of painted walls at the Temple of the Frescoes at Tulum was caused by the exhaust of tour buses that stand for hours with their motors running in front of the stone structures.
Indeed, archeologists said one reason the Guatemala ruins have largely escaped similar damage is because they are less accessible to tourists. Another reason, Dr. Reents-Budet said, is that the remote sites have not been cleared of overarching vegetation, which acts as a screen protecting the stones against much of the acid rain fallout.
Although some stones can be protected with chemical treatments, Dr. Lewin said, "The only safe thing to do at this stage is to make copies of prized art objects and put the originals in a protected indoor environment."
This has been done with the statues that serve as the outer columns at the Parthenon in Athens. The statues, or caryatids, in place now are copies. The Michelangelo David on view in Florence is also a copy. The solution for the Maya treasures will not be simple, archeologists said, because there could be no way to copy the grandeur of a Palenque or Chichén Itzá.
Ms. Libby Phipps, Memberships
Apartado Postal 343, Administracion 1
Merida, Yucatan, Mexico
The Maya Monkey
by Rosa Raquel Romero de Barajas
To the Maya the monkey is a divine creature, prominent in mythistory and a source of wonder in this life. The monkey represents both the sacred, the underworld and the man of an earlier creation.
The Maya adoration of the monkey is based on the creation myths of the New World. We live in the fifth existence we learn in the creation myth of the Maya, the Popol Vuh. Once, long before the current world existed, men were made of wood. These hapless people were punished for their sins by being destroyed, and those few who managed to survive, became monkeys. A Maya woman from Campeche tells how her grandmother at the turn of the century told with delight that these wooden men were destroyed in a great flood, and the only survivors, a man named Noah and his family, became the monkeys from which all other primates are descended.
There are many variations on this destruction myth, but the key elements are constant: the men of wood were destroyed in a great flood (or, in a few versions, devoured by jaguars), and the few survivors were turned into monkeys.
The gods, however, refused to give up and then created a nurturing man made of maize. In the Judeo-Christian tradition man is made of dust and in Mesoamerica man is made of maize. Westerners are taught they will return to dust, and the Maya are taught they are nurturing beings.
As survivors of an earlier creation, monkeys, then, are mankind's ancestors. Monkeys are the spiritual progenitors of human beings. Monkeys are, for the Maya, merely other kinds of people. This is one reason why the first Europeans to arrive in Mesoamerica were the source of such amusement. Who were these white, pale monkeys? the Maya wondered. That we Westerners continue to be a source of amusement to the native people of Mesoamerica is self-evident: how many times, when speaking to the Maya, does one see a bemused smile and laughing eyes? (They are, it seems, dealing with simians.) D. H. Lawrence was acutely aware of how his white flesh and hairy face made him ridiculous to the Zapotec in his employ. A certain resentment is evident when he writes of his experiences in Mexico for he found no comfort in being considered a kind of monkey.
This notion of seeing others as non-human is not exclusively Mesoamerican, however. At the time of the Conquest, it must be remembered, Europe had just recently triumphed over the Moors. The collapse of Granada on 2 January 1492 not only provided the loot necessary to finance Columbus' journey later that year, but it was a religious, political and cultural triumph of Christianity over nonbelievers. The Moors, first pushed back from what is now Italy, Switzerland and France, had now been expelled from the entire Iberian peninsula. Thus their presence on the mainland of Europe -- the home of Christendom -- was completely ended.
And this victory (in the name of Christ) had profound repercussions on the Western notion of self. In Spanish this philosophical victory manifested itself linguistically: the very word Christian, "cristiano," came to mean "human." Thus to be Christian was to be human. By implication nonbelievers are other kinds of beings, not quite human. In pragmatic terms, by defining humanness in this way a whole world of rationalization is possible: non-Christians are not entirely human and the commandment against murder does not apply. And to this day this linguistic legacy survives: in Spanish "cristiano" means both Christian and human.
When the Europeans first arrived in the New World they encountered millions of other beings who, like the Moors, Jews and Arabs, were in their minds not quite human. And the Maya (as well as the Aztecs and Incas, for that matter) witnessed the migrations of these new and clever monkeys with very hairy faces and extremely clammy complexions. These new people were a funny, repugnant sort of monkey.
So when the people of the Old World first met the people of the New World, each considered themselves to be human, and the other, different kinds of beings. Is it any wonder that neither really understood the other?
There is an important difference about each group's mindset to be considered. To the European, these other kinds of beings had to be converted to their faith, or destroyed. To the Mesoamerican, these other kinds of beings symbolized the divine, the underworld and the ancient.
In the creation myths of the Maya peoples, monkeys play a dominant role. In one version of the Popol Vuh we are told how monkeys first came to occupy their unique place among all animals. Hunahpu and Xbalanque are the Hero Twins who, through clever tricks, deceive the Lords of the Underworld. As the culture heroes of the Maya, their adventures form the basis of Maya mythistory in the same way that the adventures of Ulysses permeate Greek oral tradition. But these Hero Twins had an earlier set of brothers: One Howler Monkey and One Spider Monkey. These older brothers (whose real names were Hunbatz and Hunchouen) were accomplished artists and dancers. But they were also envious of their younger brothers, for they knew that their younger brothers would become the Hero Twins.
As it happened, one day the older brothers took their younger siblings to hunt for birds with the intention of harming them. The older brothers climbed a tree that (through magical powers) knew of Hunbatz and Hunchouen's evil intentions, and began to grow taller and taller, lifting the older brothers ever closer to the heavens. The tree grew so high up that the older brothers were unable to climb down again. In desperation they loosened their loincloths and tried to climb down, but, to their amazement, their loincloths became tails and they became monkeys.
The younger set of brothers, horrified at the fate of their older brothers, ran to their grandmother. When they brought her back to the scene, the older brothers, now turned into One Howler Monkey and One Spider Monkey, began to shake the limbs of the tree violently, tossing refuse down below. One even defecated on his younger brothers and grandmother. It wasn't until the Hero Twins began to play a flute and beat a drum that the monkeys calmed down and becoming entranced, began to dance. They climbed down the tree and followed their younger brothers back home. These dancing monkeys were such a source of amusement, so funny in their antics, so clever in their ways, that the younger brothers and grandmother couldn't help but burst out laughing. Their feelings hurt at being ridiculed, the monkeys ran away to the forest to live high atop the trees forever. This is where they are presently.
This incident is remembered to this day in Maya rituals. Throughout Maya villages in the highlands (Chiapas, Tabasco and Guatemala) men dress up as monkeys and dance in whimsical fashions, and, at times, engage in mischief. These festivals also reenact the disrespectful conduct of One Howler Monkey and One Spider Monkey displayed in throwing branches and refuse down at their younger brothers and grandmother. One purpose of these festivals seems to be that of a gentle reminder to the living: there are consequences for those who harbor malice or deviate from accepted forms of social conduct. But there's more to it than that. The lives of One Howler Monkey and One Spider Monkey are re-lived in these festivals, revealing the importance of mythistory to the Maya.
Monkeys are often associated with the sacred and the divine. They populate scenes of the underworld on Classic Maya pottery; they adorn sculptures and murals throughout the Maya area. Maya monkeys live high in the forest canopy, suspended between the earth and the heavens. They can effortlessly come and go between the ground and the highest point of the rain forest. In contrast, mankind is a terrestrial creature, earthbound. Humans are restricted to the ground and live physically beneath the monkeys. Thus monkeys are above men, in more ways than one. By living close to the heavens, monkeys reaffirm their status as ancestors who merit respect.
That monkeys are associated with the divine is an easy conclusion. As the Popol Vuh tells us, One Howler Monkey and One Spider Monkey only descended when the Hero Twins began to play music. The monkeys dance and are playful. And so is the Sun God of the Maya. Observers have noted that, at least where the kin period glyphs are concerned, where the representation is not of the Sun God, then it is of the Monkey-Man God. The "Monkey-Man God" phrases it rather nicely. To the Maya, monkeys are interchangeable with the Sun God (to see either, one must remember, one must life his eyes to the heavens) and they inhabit a space that separates this world from the heavens and approximate the concept of divinity. They are a kind of sacred person.
The same is true in Classic Maya art: monkeys are either very human-like in dress, pose of activity depicted, or people are simian in their conduct. This is an interesting observation when one considers that in Spanish to call someone monkey, "mono," is to call him (or her), "cute" and a "joker." If in the Romance languages of Europe humans can be "cute jokers" by being called "monkey," it is not surprising to find similar metaphors used by the Maya.
These ideas are further reinforced by the links between monkeys-as-ancestors, monkeys-as-divine and monkeys-as-underworld creatures. Ancestors are ancestors and ancestors are beings who have lived before us. In the Temple of the Inscriptions in Palenque, the Sarcophagus Cover depicts Pacal descending into the Underworld. On his belt is an image of a monkey. Pacal is being welcomed back. As Pacal descends, symbolically, he rejoins those who have gone before him -- including the simians.
According to a Maya scribe from Quintana Roo, the underworld is inhabited by dwarfs, monkeys -- and Europeans. At first it is curious that monkeys are associated with the frivolity of dance and music as well as with death and the underworld. But there is a connection. There are two kinds of monkeys prevalent throughout the Maya area: spider and howler. The spider monkey, with wiry, long limbs is a joyous creature. His face is capable of many expressions and his disposition is kind. The howler monkey, on the other hand, is of more sturdy stock, whose howls sound like someone grieving. One Spider Monkey may be associated more with laughter and pranks, life and joy, while One Howler Monkey may be associated more with seriousness and work, death and duty. Spider monkeys laugh. Howler monkeys cry. And, as we know all too well, opposites attract.
Spider monkeys are frivolous and mischievous. In Classic Maya art they clown, play tricks and are sexually risqué -- in one scene a spider monkey caresses the breast of a woman and in another a spider monkey makes love to the Moon Gopess. In contrast, howler monkeys take life seriously, are hard workers and creative artists -- in one scene a howler monkey carefully crafts a ceramic vase and in another a howler monkey plays beautiful music. The laughter of life is contrasted with the seriousness of life.
That Maya monkeys can be associated with the broad spectrum of human emotion -- from joy to grief -- further reinforces the idea that monkeys are mankind's ancestors, that they are divine and that they are creatures closely linked to humans. Maybe this is why the Maya accepted the Europeans. (The fact that the early Europeans had firearms helped, no doubt.)
Nevertheless, there is something quite comforting about the Maya view of monkeys. It is so easy to identify with the Maya, for their view of monkeys is so generous in spirit. Westerners have also long been fascinated with primates. The work of Jane Goodall with chimpanzees and the plight of the mountain gorilla capture our imaginations. We see so much of ourselves in these simians that we are disturbed, indeed, haunted, when we learn that chimps engage in warfare, murder and, reportedly, at times will consume the flesh of their victims. Rather human-like behavior. The mythistory of the Maya suggests similar views of the primates. In this fascination with primates the peoples of the old and New Worlds are alike.
We are also alike in dark, perverse ways. The Maya thought nothing of killing another human being in a religious ritual, but to kill a monkey was tantamount to murder. Observers have reported that, when on expeditions, Maya guides are grief-stricken if a monkey is accidentally killed. It is almost as if a child had died. In Western history, also, the peculiar prevails: during the Crusades it was perfectly acceptable to kill an enemy's children, provided the were baptized first in order to protect their souls! (And today, our mixed feelings on human life are evident; capital punishment is still acceptable in the U.S.)
The predisposition of the Maya to consider monkeys as a kind of human lends nicely to current science as well. Primates are our closest living relatives, if one accepts the theory of evolution, and the likeness of the monkey to the human is undeniable. This may be why monkeys cannot be anthropomorphized: they are already "anthros," so to speak. Their facial expressions, their bodies, their intelligence and their presence are all very human. The Maya, evidently, recognized this which is why it's very difficult to identify the subjects of their artistic representations as monkeys themselves, humans whose features resemble those of monkeys, or humans disguised as monkeys.
There is something amiss in all of this, however. One reason why humans throughout time have looked at monkeys with such ambivalence -- representing both merriment and death in the case of the Maya -- may lie in man's self-image: monkeys are a reminder that while a monkey may be a different kind of person, a person is definitely some kind of monkey. One reason why it is impossible to anthropomorphize simians is that it becomes a question of degree: how much more of an animal is a howler or spider monkey than is a human? The Maya know the answer to this.
The Maya realize that when we see a monkey, it's like looking in a mirror.
Rosa Raquel Romero de Barajas, who is fortunate enough to have a family of spider monkeys living in her mango and avocado trees, lives in Merida.
Ms. Libby Phipps, Memberships
Apartado Postal 343, Administracion 1
Merida, Yucatan, Mexico
Pretty in Pink: The flamingo's bold colors belie its sensitive and threatened nature
by Joe Keenan
© 1996 The Nature Conservancy
Scientific research is not always fun -- especially if you're trapped in a hot observation blind for hours at a time. But as Felicity Arengo huddles in a makeshift blind in the middle of a tropical estuary in Mexico's Celestun Special Biosphere Reserve, she's having the time of her life.
Just outside the blind, starting not more than 100 feet away, is a flock of several thousand shocking-pink Caribbean flamingos. They are stamp-feeding, neck-snaking, squabbling with their neighbors and honking like a flight of October geese. Arengo is trying to keep her mind on the behavioral data she is here to collect. Instead, she is transfixed by her subjects.
"They're goofy, they're fascinating, they're ridiculous," she marvels, searching for a word that will capture the spectacle. "Even after all these months they seem like something out of Walt Disney."
Arengo, a researcher from the State University of New York at Syracuse, has spent more than 10 months of the past two years huddled in this blind and observing Celestun's flamingos. Flocks of flamingos have been coming to Celestun each winter for as long as the oldest fisherman here can remember, and Arengo is hoping to discover why. By correlating the estuary's substrata, salinity and water levels with the flamingo's feeding behavior, she is trying to understand what the birds need to survive -- and what we need to protect them.
A healthy, productive estuary on the west coast of Mexico's Yucatan Peninsula, Celestun harbors extensive mangrove forests and is critical as a nursery area for local fisheries. It is also one of The Nature Conservancy's "Last Great Places," and the Conservancy has been working with the Mexican government and Pronatura Peninsula de Yucatan, its in-country partner organization, to beef up protection, community outreach and compatible development projects at the reserve. Celestun's world-class wetlands alone are worth the effort, but saving the flamingos not surprisingly gets top billing.
Protecting the flamingo has been a priority for conservationists for more than four decades. In the 1950s, biologists began to take note of the bird's steady disappearance from many traditional nesting colonies. Robert Allen, of the National Audubon Society, conducted the first thorough census of the Caribbean flamingo's scattered populations and confirmed what many had feared: The bird had been reduced to only four regular nesting colonies, and these were under siege.
Over the following decades, the conservation community took action: Reserves were declared and guards posted at the Great Inagua, Bahamas, site that hosted the largest colony, and where villagers had regularly rounded up hatchlings and marched them into town to sell. In Mexico, federal authorities prohibited the taking of eggs by local residents, and two reserves -- Celestun and Ria Lagartos -- were decreed. Several groups led by National Audubon cut a deal with a salt mine on the island of Bonaire to set aside 130 acres for flamingo breeding, and they are breeding there still.
From Allen's estimate of 21,500 Caribbean flamingos in 1956, populations have recovered to an estimated 90,000 individuals today. The Mexican population alone has increased from a low of 6,000 birds in the mid-1970s to a stable 25,000 birds just 20 years later.
But if a battle to save the flamingo has been won, the war is just beginning. New threats to this improbable bird, and new knowledge of its needs and habits, have conservationists worried again.
flamingos Of the four flamingo species that inhabit the Western Hemisphere, three -- the Andean, Chilean and James' flamingo -- live mostly on salt lakes above 12,000 feet in the Andes. At least 200,000 Chileans are thought to exist, followed by Andeans and James' with about 50,000 birds each. Estimates are notoriously unreliable: only aerial counts can cover the large expanses these birds inhabit, and the three species are generally not distinguishable from the air. The fourth species, the Caribbean flamingo, found at Celestun and on several islands in the Caribbean, is strictly a coastal dweller and is the most brightly plumaged of all flamingo species.
Flamingos typically feed with their heads upside-down and under water, sifting through the stirred-up sediment with their thick, spine-covered tongues. "They have two common ways of feeding," recounts Sandy Sprunt, retired vice-president of field research for the National Audubon Society and one of the world's foremost authorities on the bird. "They stomp in a circle with their head in the middle, or they walk forward, weaving their heads back and forth, leaving a serpentine trail in the algal mats."
A feeding flock can stir up enough silt to create channels of mud extending miles downstream. The unforgettable sight of 10,000 birds stomping, snaking and sifting is what awaits and awes visitors at sites such as Celestun.
Although it doesn't look the part, the lanky, high-stepping, gaudy pink flamingo is one of the toughest critters around. They have been known to drink scalding water from geysers and to wade in caustic water that would peel a human's skin off. Caribbean birds typically withstand summertime highs of 110 degrees Fahrenheit, while South America's highland species nest on icy islands and tolerate nighttime lows of zero.
But flamingos are also extremely skittish animals. Their nesting colonies of thousands of birds are extremely vulnerable to disturbances, and as a result tend to be located in inaccessible expanses of salt flats. But as resort development and settlement increase in coastal areas, inaccessible sites are becoming harder for the flamingos to find.
Human encroachment is the flamingo's new enemy in much of its range. Such diverse side effects of settlement as feral dogs and pigs, vacationers on jet skis and overflights by small planes can cause entire colonies to be abandoned.
Worst of all, new roads linking barrier islands and coastal villages to inland towns and cities often are built without sufficient culverts to permit natural water flows, nutrient cycling and drainage. At several places, new roads have acted as dikes and flooded salt flats that traditionally would dry out after the rainy season. Entire colonies have been forced to move.
Even under natural conditions, flamingos are tireless wanderers. Indeed, researchers are just beginning to understand the extent to which flamingos move about and depend on a wide range of habitats and water conditions. Linked to extreme wet-dry cycles of the birds' hypersaline haunts, these movements take the birds from lake to lake in the Andes, from island to island in the Caribbean and from one side of the peninsula to the other in Mexico's Yucatan.
Nesting birds on Bonaire, 75 miles off the coast of Venezuela, fly each night to the South American mainland to gather food for their young. Colonies in Cuba -- the least known of the birds' populations -- are thought to abandon the island altogether in extremely wet years, nesting instead at Inagua. Twenty nesting James' flamingos were counted at Bolivia's Laguna Colorada one year, 26,000 were tallied nesting there a few years later.
The Yucatan peninsula population has traditionally migrated each year from hypersaline nesting grounds at Ria Lagartos reserve to brackish wintering grounds at Celestun on the peninsula's west coast. Since Hurricane Gilbert in 1988, the Yucatan birds have moved their nesting colony twice, seeking the right conditions and a new home.
Saving a bird that won't keep still has proved a challenge to conservationists. Traditional tactics -- decreeing a protected area and posting guards -- will evidently not be enough to keep the flamingo safe. Instead, specialists point to the need for an ecosystem approach that crosses reserve and even international boundaries.
"Reserves were established for flamingos based on what was known about them at the time," says Arengo. "But now we're discovering that their distribution is broader than that. They're all over the coast."
Studies by Arengo and others have demonstrated that flamingos require different conditions at different points in their life cycles. Adult birds specialize in feeding in high-salinity waters, for instance, but younger birds, possibly because of undeveloped salt glands, tend to favor fresh waters.
Added to the fickleness of flamingos' habitat needs is the variability of the habitats themselves. Most of the areas that flamingos inhabit are subject to severe wet and dry cycles. Salt flats that are too deep for the birds one month can be bone-dry a few months later. In such a change-prone environment, the permanent conversion of wetlands is systematically cutting into the flamingos' chances of survival.
"It's all a question of playing the odds," says Guy Baldassarre, Arengo's professor at SUNY-Syracuse and the forces behind flamingo studies at Celestun for the past 10 years. "If the flamingo is looking for certain conditions and before there would have been five or six such sites, now there may be one or two." The implications are clear: One day, instead of one or two, there may be none.
"When you protect fragments, you're putting all your eggs in one basket," says Baldassarre. "We've got to protect the hydrological integrity of the entire coastal wetland system. We've got to prevent these systems from being crisscrossed by roads."
Ironically, the newest threat to the flamingos may be the very eco-tourists who come to marvel at them. In Bolivia, nearly 10,000 people a year visit the highland flocks at Eduardo Avaroa park, while Bonaire has dubbed itself "Flamingo Island" to remind tourists what its main attraction is. At Celestun, some 12,000 tourists visit the reserve each year specifically to witness the spectacle of its feeding flamingos.
This much attention has its price. At Celestun, for instance, tourists frequently offer handsome tips to the boatmen to ride their boats straight into the flocks, forcing the birds to fly. And it is not unheard of for boat operators to fire bottle rockets into flocks when they assemble too close to the docks -- where tourists can watch them without paying for a boat ride.
More subtle, but potentially as dangerous, are the impacts caused by repeated disturbances from tour boats. Eduardo Galicia, another of Baldassarre's students at SUNY-Syracuse, recently completed a year-long investigation into tour boats' impact on flamingo behavior at Celestun. His conclusion: Disturbed flocks take an average of 20 minutes to return to pre-visit behaviors, and a flock receives an average of 10 such visits per day. All told, he calculated, disturbed flocks spend at least 13 percent less time feeding than undisturbed flocks.
Yet eco-tourism, properly managed, offers an unequaled opportunity to involve local communities in the protection of the flamingos. Visitors bring money into local economies and create economic incentives for protecting the flamingos and their habitat. Properly informed, tour operators can be expected to take steps to protect the birds that are their bread and butter.
To that end, in November Galicia organized a presentation of his study results for Celestun's tour-boat operators. Projecting slides on the back of a discarded soft-drink billboard that the boatmen erected for the occasion, the biologists explained how different viewing variations -- distance from the flock, movements of the boat, frequency of visits -- had different effects on the flamingos' feeding behavior.
"The first thing that impressed me was the pride they had in 'their' birds," recalls Galicia. "The second was the speed with which they understood the implications of my study and started making suggestions."
The recommendations from Galicia's study are being incorporated into a management plan for Celestun that is being prepared by Conservancy partner Pronatura Peninsula de Yucatan, in conjunction with Mexico's environmental authorities. Through the "Parks in Peril" program, Pronatura plans to establish a visitors center at Celestun to educate tourists while routing income from entrance fees and gift-shop sales into park management.
Despite eco-tourism's risks, many conservationists feel that it holds the greatest promise for the lasting protection of the flamingo. By linking conservation with economic benefits for the community, the flamingo flocks give villagers a vested interest in keeping the reserve's ecosystems in pristine condition.
Already, Celestun's small but bustling tourism trade recognizes the importance of happy flamingos to its economic well-being. Just three decades ago, locals say, it was still common practice to shoot flamingos for food. Now, each fall, townspeople look anxiously skyward for the return of the large flocks of pink birds that attract growing flocks of tourists.
"If you have advocates at the local level, you have long-term protection," says Baldassarre. "And the flamingos are doing that in spades."
Visiting North America's Largest Rainforest: Punta Laguna, Where the Spider Monkeys Live
1996 Mesoamerica Foundation
Every year over two million Americans and Canadians visit the resorts of Cancun and Cozumel on the Yucatan Peninsula's Caribbean coast. Not far from either destination is a tropical forest reserve where native people live in harmony with their environment. The place is Punta Laguna, Spanish for "Lagoon Point," and this is the closest tropical rain forest habitat for anyone living in the continental United States and Canada. A place of compelling beauty, Punta Laguna guards ancient Maya ruins and a contemporary village of Maya people whose presence in the forest is sustainable and in harmony with their environment. It is also a home for the boisterous Spider Monkey.
For more than ten years, community members of Punta Laguna have been guarding the archaeological ruins and protecting the forest and wildlife around them. It has not been an easy task for the Maya. In recent years crops have been depleted by droughts and hurricanes, which are part of recent global weather patterns. The Maya have been forced to consider other ways to support itself; the other alternative -- to migrate to the cities -- would disrupt their traditional lives and it is something they do not want to do.
Punta Laguna has also confronted familiar challenges: Tropical woods from the forest is in demand. Unscrupulous outsiders offer money for baby Spider Monkeys and other animals. People capture toucans and steal rare orchids and other tropical flowers. Cattle ranchers encroach on the forest, often promising cash to the Maya residents, who are poor.
So far, these temptations have been resisted by the Maya, but it has meant much hardship and sacrifice. The Maya are a proud people, aware of the beauty of their environment and respectful of their heritage. With the help of conservationists, however, in spite of all these pressures and economic incentives to do otherwise, we have worked to save and protect Punta Laguna.
Only the tenacious belief that the forest is life itself has compelled the Maya to preserve the outstanding beauty and ecological diversity of Punta Laguna. It is for this reason that we can still seek the Spider Monkeys roam free throughout the forest canopy. The Spider Monkey is trusting of people and their presence reminds us of duty to protect the forests from those who would harm it.
We have worked to clear paths so interested visitors can come and see the wildlife and the ruins of the ancient Maya civilization.
- One of the main attractions here is the troop of Spider Monkeys that share our forest. Nowhere else on the Yucatan Peninsula will you have a better opportunity to observe this now-rare and endangered animal. It is mainly threatened by habitat destruction and the illegal pet trade. Because of the consistent protection of the Maya community that live in Punta Laguna, the Spider Monkeys are not really afraid of people. They can often be seen feeding nonchalantly in trees right above our houses! They are, however, naturally wary of people and it is best to be quiet if you want to see them close.
Where Punta Laguna is located
- We are located on the road between Nuevo Xcan and Coba. It is a tropical forest with a large lagoon and several cenotes -- large, fresh-water sink holes. Our community shares its land with Spider Monkeys and over 100 species of birds, turtles and other wild animals.
The people who live here
- Our small community has 50 people of Maya ancestry. Although it was founded only fifty years ago, the ruins in the forest tell us that Maya have lived here for at least one thousand years! Like our ancestors, our lives revolve around the cultivation of maize, or corn. We use our forest in special ways to provide fruit, honey, medicinal plants, chicle (chewing gum) and materials to build our homes.
The conservation project
- Pronatura, a conservation organization, learned about our efforts in Punta Laguna and decided to support us in the protection of our natural resources. Pronatura has collaborated with us to develop visitor facilities, and they provide us with financial support and technical assistance as is needed. Mesoamerica Foundation is now helping us as well. We are excited about our new activities. We are keeping our goals small in order to protect our forest and make sure that it is developed and managed by us, the local people. In the next few years we hope to bring electricity, water and a school to our community.
What to do when you visit us
- Take a hike. Follow the trails through the forests. Be sure to take plenty of water. It is warmer than you think and you can dehydrate without noticing.
- Spy on the Spider Monkeys. They are usually in the trees overhead, and will come close to a visitor who has a piece of fruit. Be careful! Spider Monkeys have bad manners and don't know their own strength! It is better to toss a piece of fruit to them, but never try to hand them something.
- Visit the Maya farmers. Most of the people of Punta Laguna are farmers using traditional Maya farming methods. Often the fields look unkempt, but that's because the Maya allow several crops to grow in one area, so while the corn stalks looks as if they are overrun by weeds, they might very well be pumpkins or squash!
- Go swimming. Punta Laguna offers a few great swimming holes. When it get hot -- and it does get hot -- nothing feels as good as a swim.
- See the Maya ruins. Where else can you explore the ruins of an ancient civilization in the middle of a tropical forest?
- Bird watch. There are toucans, parrots, hummingbirds and hundreds of migratory birds. More different species of birds visit the Yucatan Peninsula than the whole United States!
- Rest under a giant tree. The forest is filled with giant trees of incredible size. They offer a cool place to stop and have a lunch, or rest for a while.
- Be Mindful. Spider Monkeys are beautiful and funny, but they are also carriers of diseases, such as rabies. This is why no one should ever approach a Spider Monkey and try to touch him. This is especially true of female monkeys with young offspring. They will try to protect themselves and their youngsters, and may bite your hand.
- We have looked after this area for generations. Certain sites are sacred to us and form part of our community's religious practices. You can help keep things as they are by listening to your guide, obeying the posted signs and leave things as you found them.
- What you can take: Pictures and memories of this experience!
- Wear good walking shoes. The trails may be uneven.
- Wear insect repellent. Ticks and fleas live in the tropical forest too!
- Watch your step. A trail of scurrying ants could go up your pant leg!
- Be quiet. If you make noise, the birds and Spider Monkeys will stop and listen to you!
- Don't take anything. Punta Laguna is a place to visit, but please don't take rocks, plants, flowers or animals. And please don't leave any refuse.
- And finally, stay with your guide. The trails are not marked and if you get lost, it won't be much fun for anyone!
The Past and Future Amazon
The climatic history of the Amazon rain forest indicates that the ecosystem is well adapted to certain natural disturbances. Does it have the resilience to tolerate human exploitation?
byPaul A. Colinvaux
1989 Paul A. Colinvaux
This article appears here courtesy of Dr. Colinvaux. A translation in Spanish will soon be published by Mesoamerica Foundation; the English text was first published in Scientific American in 1989.
The rain forest covering the vast Amazon River basin of South America looks from the air like a uniform green carpet cut here and there by water. Actually the forest is anything but uniform. The "carpet" is the forest's canopy, formed by the broad leaves of the many different kinds of giant trees, and this canopy is but the topmost layer of an ecosystem supporting more species than any other region on earth. The rain forest is home to perhaps 80,000 plant species (including 600 kinds of palm alone) and possibly 30 million animal species, most of them insects.
This remarkable diversity was once presumed to be a product of an ever-lastingly stable climate of abundant rain and warmth. Spared the short-term catastrophe of winter every year and the long-term disaster of glaciation, theory said, the tropical domain known simply as "the Amazon" would lose few species and accumulate many. Yet evidence from the field suggests that the Amazon is subject to changes on all time scales, including cooling when ice-age climates loose glaciers over more northern territories. Moreover, far from being disastrous to life in the Amazon, the moderate climate disturbances in the region may actually help account for the splendid diversity of the Amazon rain forest today.
The influence of past climates on species diversity in the Amazon ecosystem is of more than academic interest; it is an invaluable predictor of the forest's ability to endure change. As human beings lay waste to massive tracts of vegetation, an incalculable and unprecedented number of species are rapidly becoming extinct. Nations with jurisdiction over the rain forest -- notably Brazil, Venezuela, Colombia, Ecuador and Peru -- need to identify management strategies that can save as many species as possible and yet be compatible with the need for economic development. Those who devise such strategies must take into account the kinds of stresses that affect species diversity, and so it is important to learn what insults the ecosystem has tolerated throughout history.
The old belief that climatic stability accounted for species diversity in the Amazon emerged, strangely enough, from observations of the deep sea. Howard L. Sanders of Woods Hole discovered high diversity among the mud-dwelling animals of the deep-ocean floor in spite of the cold darkness and low biological productivity there. He argued that such hostilities to life are offset by the perpetual sameness of the place. Without significant fluctuations in physical conditions, the extinction of species that are adapted to prevailing conditions should be rare. In the course of time new species would continue to evolve, and so the rate of speciation would be greater than the rate of extinction, resulting in the accumulation of great diversity.
Sanders suggested that the Amazon forest and other tropical forests could be thought of as analogous to (albeit more productive than) the deep sea: places with a stable supply of annual moisture and warmth in which extinction should be rare. The absence of winter and glaciation and evidence that rain-forest trees have persisted for some 30 million years or longer somewhere in the 3,000-kilometer-wide, 1,000-kilometer long Amazon supported this view.
Then, in 1969, several observations cast doubt on the validity of the stability theory for the Amazon, implying that the climate there has fluctuated significantly in the past. Jürgen Haffer, then of the Mobil Research and Development Corporation, noted that different corners of the basin held their own, separate bird faunas in spite of the fact that essentially unbroken green forest spread from the western edge of the Amazon to the Atlantic Ocean in the east. Haffer and other biologists also noted species disjunctions among butterflies and a few other groups. This pattern presented a glorious puzzle to workers studying the distributions of plants and animals: Why would the populations have become isolated if the habitat in which they lived was continuous?
Haffer proposed an explanation so bold and logical that many of us wished we had thought of it first. He suggested that the modern isolation has its roots in times past, in the latest ice age. Observing that the regions of species isolation generally centered on outcrops of high ground and that lowlands are drier than uplands, he proposed that in glacial times the Amazon lowlands become a sea of near-desert arid plain; meanwhile the more elevated regions become islands of moisture and hence serve as refuges for the fauna and flora of the rain forest. Populations that were once continuous diverge along this ecological gradient and become permanently separated as they adapt to their upland habitats.
This hypothesis has great appeal because it appears to explain not only species disjunction in the Amazon basin but also the unusual species diversity there. The ice-age refuges would, as the earlier stability hypothesis predicted, protect existing species from extinction. But the periodic geographic isolation of related populations (there have been an estimated 13 ice ages to date) would facilitate ever-increasing divergence.
For the refuge hypothesis to stand there has to be proof that the lowlands of the Amazon, which now support wet forest, do indeed dry out in glacial times. No one has yet found compelling evidence that the Amazon was actually arid, although circumstantial evidence has been provided by computer models and also by sediment samples drawn from several sites in the tropics.
For example, John E. Kutzbach and Peter J. Guetter of the University of Wisconsin at Madison, have experimented with computer models of the global ice-age climate, predicting reductions of up to 20 percent in the monsoon rains in the tropics. Such a reduction would certainly spread aridity into strongly seasonal regions those with true dry periods each year including at least some parts of the Amazon. (Many so-called seasonal regions in the tropics do not have true annual dry periods, merely ones that are less rainy than other seasons).
Daniel A. Livingstone of Duke University published some of the earliest field data addressing the issue of aridity. He found by examining fossilized tree pollen, which is a good indicator of the local flora, that several tropical rain forests in modern Africa grow where dry woodland or savanna grew between 12,000 and 20,000 years ago; that is, late in the last ice age (from about 10,000 to 70,000 years ago). Hints of similar ice-age aridity in what are now wet tropical regions also came from outside the periphery of the Amazon basin, suggesting that what was true for ice-age Africa might also have been the case of the Amazon basin.
I myself gathered data suggestive of Amazonian aridity from the Galápagos Islands, which are about 2,000 kilometers directly west of the western-most edge of the Amazon basin on the Equator. A well-dated sediment core, or pipeful of undisturbed sediment, from under the floor of the Galápagos' one freshwater lake shows that the lake was without water in the last ice age. It did not fill until the onset of the Holocene (the current, postglacial period).
On the continent itself others have found similar evidence at sites north of the Amazon. In northern Venezuela what is now deep Lake Valencia was without water at the end of the last ice age, and what is now a swamp on the coast of Guyana held dry vegetation. Different work suggests that a strongly seasonal forest to the south of the Amazon basin, near Säo Paulo, Brazil, was arid as well.
More evidence that the glacial-age Amazon lowlands might have been arid has been obtained from deep-sea cores from the Atlantic Ocean, right near the mouth of the Amazon River. John E. Damuth and Rhodes W. Fairbridge, then of Columbia University, have found that sediment delivered from the east-flowing river during the last ice age included a small fraction of feldspars, minerals from crystalline rocks, that could conceivably have been the erosion products of an arid landscape.
In spite of the abundance of the circumstantial evidence for ice-age aridity, I have become convinced that the evidence is not strong. Georg Irion of the Research Institute and Natural History Museum in Frankfurt has shown that he feldspars in the Atlantic deposits probably came from rocks in the Amazon basin, but not from rocks on the surface. The sea level fell in the ice age, and the Amazon's many tributaries presumably cut their channels deeper at the same time, carving the feldspars in the process.
The sediment-core data from the Galápagos Islands and around the Amazon on the mainland are also weak because the regions from which the sediments were taken, although closer than Africa, are still quite a distance from the Amazon rain forest. Moreover, the regions frequently come under the influence of different climatic forces. Between the study sites and the Amazon basin are the tall Andes, the Venezuelan and Guiana Highlands and another immense line of hills known as the Mato Grosso (the great scrub), which constitute respectively the western, northern and southern boundaries of the basin. Each of those boundaries is a site of climatic tension, so that the climate on one side of the heights is often quite different from the climate on the other side.
It may be that in the strongly seasonal regions of the modern Amazon reductions in the monsoon rains do result in semiaridity during glacial times -- perhaps just below the Guiana Highlands in the northeastern corner, immediately to the west of the Mato Grosso in the southwest and in some parts of the central basin in Brazil. For most other, wetter regions of the Amazon, where annual rainfall is from two to five meters, it is quite unlikely that even a 20 percent reduction in the rains would make any practical difference to life.
In 1985 the fact that there were no radiocarbon-dated, glacial-age fossil data of any kind from Haffer's postulated refuges or the lowlands of the Amazon prompted me and my colleagues at Ohio State University to seek data from the Amazon proper. We found the only fossils that have yet been dated to an ice age. They suggest that the Amazon was not dry. The region did undergo a significant change, however; it became cooler by several degrees Celsius.
We found our specimens by serendipity, while searching the western-most edge of the rain forest, in eastern Ecuador, for old lakes whose sediments we hoped would hold ancient records. At one point we found ourselves on a dirt road in Mera, whose 1,100-meter elevation in the eastern foothills of the Andes places it close to the upper limits of today's rain forest and within one of the major putative refuges. There we noticed old tree stumps and logs that we embedded in an exposed patch of sediment. Because we had a bit of time on our hands as we waited for a flight to a distant lake, we took a collection of sediment and wood samples. Radiocarbon dating of the wood indicated that some samples were 35,000 years old and others 26,000 years old. Although earlier than the time of maximum glaciation than the time of maximum glaciation in the most recent ice age (18,000 years ago), these are dates of glacial times.
Another analysis of the wood samples showed they included softwoods, meaning conifers. Now, the only conifers in modern Ecuador are Podocarpus trees of the Andean forests, which today grow at elevations that are at least 700 meters above the Mera site. Indeed, pollen analyses of the sediment samples showed that the ancient forest at Mera had a strong Andean cast to it and that it has no direct analogue in modern tropical America.
We conclude that the Podocarpus trees, which require both moisture and the relative coolness now found only in the mountains, grew at least 700 meters lower in glacial times. Taken together with the pollen data, this conclusion suggested to us that Mera was moist during the last ice age but was too cool to support a modern kind of rain forest. A standard formula suggests that the temperature in the Ecuadoran foothills was at least 4.5 degrees Celsius cooler than it is today. (The formula assumes that in moist air the temperature cools six degrees Celsius for every 1,000 meters of ascent up a mountain.)
There was, then, no refuge for warmth-loving species in Mera. If the temperature depression was widespread in the Amazon, as seems reasonable, then other high-lying parts of today's rain forest might also have been too cold to support rain-forest refuges. Given the well-established fact that typical rain-forest trees persisted somewhere in the Amazon basin, the data suggest that the rain forest was restricted to somewhere in the lowest region, where refuge theorists had predicted aridity. If the trees did in fact survive only in the lowlands, it follows that the lowlands were not arid, or at least were not uniformly so.
Obviously more than one data set from the ice age and data from the coldest part of the period are needed before a picture of the ice-age Amazon can be reconstructed with confidence. Still, the existing evidence suggests that the refuge scenario is no more supportable than the notion of imperturbability that it replaced. It also suggests that the rain forest shrinks in response to ice-age cooling and expands again during warmer interglacial periods, such as the one we are in now. In essence we have the inverse of the refuge picture: some part of the lowlands remains as a relatively warm, wet preserve for rain-forest trees and the uplands -- formerly thought to be refuges -- become inhospitable.
What then explains the species diversity and the species disjunctions identified by biologists? Changes in the climate between glacial and interglacial periods may still be important, albeit not in the way the refuge theorists predict. The migration I propose of rain-forest species to higher ground in warm interglacial periods such as the present one would provide opportunities for the formation of novel mixtures of species. Populations from the warm lowlands of glacial times could then become adapted to their new upland conditions and diverge from their ancestors. Perhaps something like that happened to the birds and butterflies now living in the uplands.
Another part of the answer certainly has to do with the varied climate and geography of the Amazon. The game of speciation has always been played across a huge playing board: the Amazon basin is almost the size of the continental U.S. All parts of the board are superficially alike and indeed have some species in common, but the territory does not hold one monolithic ecosystem. Rather, there are large regional and local differences in rainfall, seasonality, soil and susceptibility to flooding, all of which can affect the mixture and evolution of species in any given area.
A further explanation for the diversity is known as the intermediate-disturbance hypothesis, put forward by Joseph H. Connell of the University of California at Santa Barbara and independently by Stephen P. Hubbel, now of Princeton University. This hypothesis suggests that the highest species richness will be found not where the climate is stable but where environmental disturbance is frequent but not excessive.
The intermediate-disturbance hypothesis concedes that massive catastrophes lead to large-scale extinction. This is what would happen if asteroids struck the earth, as they may have done at the time of dinosaur extinction. But lesser and local catastrophes, such as storms and flooding, do not generally extinguish entire species. Instead, by killing some fraction of a dominant species, the smaller hazards prevent winner-take-all competitions from going to their conclusion (extinction for one species) and give initially weaker organisms the opportunity to establish themselves.
The effect of intermediate disturbances can be seen quite readily in rain-forest trees. Great gashes and succession communities are everywhere in the Amazon and other tropical rain forests wherever gaps are cut in the forest by the felling of large, sun-blocking trees (such as rubber trees and balsa), various species of short-lived, sun-loving plants, together with their associated fauna, populate the gaps. This process initiates a series of successions that, if they go undisturbed, culminate centuries later in the groupings of giant trees characteristic of mature rain forests. The big rain-forest trees actually fall fairly easily because their roots are shallow: often half of their root mass is in the top 20 centimeters of soil. All it takes is a strong push by wind or the washing away of topsoil at the base of the tree by floods or moving streams.
A growing body of data suggests that at least throughout the Holocene (and probably throughout history) the Amazon has been perturbed in one region or another by storms, erosion and other forces. Indeed, the Amazon's topography apparently changes from century to century and even from decade to decade.
Some of what is known about the Holocene's history comes from the sediment cores my colleagues and I obtained from the Ecuadoran lakes alluded to above. Our oldest data are from lakes in volcanic-explosion craters, the only crater lakes yet known in the Amazon. One of these lakes, known as Kumpak in the Shuar language of the local populace, has muddy, oxygen-depleted water typical of an Amazon river-fed lake. The other lake, Ayauch, is transparent and blue, with oxygen deep in the water. It is almost like an alpine lake -- a wildly exciting and improbable thing to find in the jungle.
Mark B. Bush, a postdoctoral fellow in my laboratory, has completed pollen analyses of the 7,000-year record from Ayauch, finding evidence for rain forest throughout most of that time, although there was a prolonged local drought 4,000 year ago, long after the ice age ended. (He also found evidence that people had grown maize in the vicinity 3,000 years ago -- earliest record of maize cultivation in the Amazon.)
Kam-biu Liu, now of Louisiana State University, found a different kind of history in the Kumpak sediments. These are banded throughout with layers of different textures, suggesting a history of heavy rainstorms that washed sediment in pulses from the banks into the lake. In other words storms have been remodeling the land Kumpak for at least the past 5,000 years.
Again in the Ecuadoran rain forest, but from the north, cores we obtained from four lowland lakes abandoned by their parent rivers centuries ago have also yielded clear evidence of at least one extended period of unusually powerful storms and forest perturbation in the west. The sediment samples from each lake were topped by a layer of gyttja, typical lake mud, first laid down 8,000 years ago, according to radiocarbon dating. Beneath this layer in all four lakes was river sediment that had been deposited continuously since about 1,300 years ago. The lakes, therefore, were left by their parent rivers roughly 800 years ago and have not been reentered since.
We postulated that between 800 and 1,300 years ago excessive rains in the mountains to the west caused massive flooding and forced rivers to spread back to old, once-abandoned channels in the lowlands, which became largely inundated. Our pollen analysis of the old river mud indicates that early succession forests were present on temporary sandbanks that formed when the floods, which presumably killed mature trees, subsided temporarily.
Marcia L. Absy of the Amazon Fisheries Institute in Manaus, Brazil, has also found evidence of flooding at the appropriate time in lakes of the central Amazon. Absy cored five varzea lakes (which are filled by rivers during the wettest and then are abandoned to evaporate slowly in the driest seasons from different water sheds near Manaus, including lakes spawned by south-flowing rivers from the dry Guiana Highlands, by north-flowing rivers from the Mato Grosso and by east-flowing rivers draining the Andes of Ecuador and Peru. Her data show that only lakes in the path of the western drainage hold the flood record -- not those in the paths of the north- and south-flowing streams. In other words the stormy period was a local phenomenon of the west and had long-range effects solely on regions in the path of the swollen Amazon tributaries.
The western Amazon, then, has been disturbed in the Holocene by at least one unusually drastic climate change, whose effects lasted almost a millennium. Doubtless other climatic events of equal long-term effect await discovery in the turbulent basin.
On time scales of a few centuries the perturbing effects of erosion by moving streams are particularly evident. Some rivers are fast-moving and wear away sediment rapidly; others are sluggish but nonetheless erode sediment as they move. Many rivers flow now through one channel, now through another. As they change direction they topple trees in their path; they also leave behind sediment ripe for colonization. All are subject to flooding in rainy periods, at which time they wash away trees on their banks and redecorate the landscape. The turbid western tributaries of the Amazon are particularly active. Indeed, various estimates suggest that 80 percent of suspended solids in the lower Amazon comes from the west.
On the basis of published measures of the sediment discharged at the mouth of the Amazon River each year, my group tried to calculate how fast the huge rivers draining the Andes are eroding the western region. That is an exercise in unsafe extrapolation, but it does suggest that many centimeters of land surface are lost every century. Perhaps half the rooting depth of a typical, mature Amazon tree can be washed away in less than the tree's normal lifetime.
Jukka S. Salo and his team at the University of Turku in Finland, working in the Peruvian Amazon, have obtained better evidence of the disturbance caused by erosion in the west. With the help of satellites they have constructed maps of different forest types, including both early succession communities (which typically grow on sediment left behind as rivers progressively more their channels) and mature communities (which become established only centuries after an old riverbed has been abandoned). From these maps they determined that in the past couple of centuries as much as a quarter of the Peruvian forest has been swept away and rebuilt as new communities.
Rivers also perturb the land on smaller time scales. With aerial photographs taken 13 years apart, Salo and his group showed that a single small river had reworked 3.7 percent of its floodplain in these few years; on the average, it had eroded 12 meters of land per year.
Most people are not surprised to learn that the Amazon forest is disturbed by storms, flooding and erosion. Few, however, expect a rain forest to be perturbed by natural fires, and yet rain-forest trees apparently do burn in the Amazon. Recently Robert L. Sanford of the University of California at Berkeley and other investigators found layers of charcoal in soil pits in southern Venezuela, at the northern tip of the Amazon basin. Radiocarbon dating showed that some of the samples were 6,000 years old and hence were deposited before human beings are thought to have entered the region. At least some of the charcoal layers, then, must be products of natural wildfires.
What would cause such fires? Rain-forest trees can be thought of as water-cooled energy traps. They spend their days absorbing intense solar radiation on the huge surface areas of their thin, broad leaves, an undertaking that is possible only if the trees can dissipate heat by evaporating immense quantities of water. Sanford thinks it possible that in a mere month without rain the trees might expend all the water within reach of their shallow roots, after which their leaves would wilt, overheat and be lost. The sun could then scorch litter under the leafless trees, enabling spontaneous combustion or lightning to set the dried forest alight. The random properties of weather can be expected to produce such a dry spell in the rain forest once or twice in a span of several thousand years.
It becomes clear that, indeed, the Amazon basin has always been a place disturbed. In ice ages, if our single data set is representative of the region, the land apparently cools and the forest is displaced. In warmer times the Amazon forest is probably subject to the kinds of disturbance identified from lake-sediment records and other records of the Holocene. Different places at different times are beset by storms, flooding and erosion, and they burn in the rare periods when no rain falls for days on end. Few patches are likely to go undisturbed for more than a century or two. The result today is a mosaic of gaps, successions and mature forest and a wonderful assortment of plant and animal species.
What does all of this say about the future of the Amazon ecosystem, now severely imperiled by humankind? The fact that species have accumulated in a place of constant change suggests that the fauna and flora can tolerate some human activity, if the activity is on the order of natural intermediate disturbances that always leave survivors. It must be emphasized, however, that nothing in the history of the Amazon seems to have approached the clear-cutting now being inflicted on the system by human beings. Such activities are more akin to the catastrophic forms of natural disturbance that have led to the extinction of vast numbers of species in the past.
Moreover, the larger animals that dwell in the rain forests cannot survive the devastating effect of modern firearms. Indeed, plant-eating primates and sloths that graze in the canopy and their flying predators, such as the harpy eagle (an engine of destruction so powerful that it can tear monkeys out of the canopy), are desperately vulnerable to shotguns. One person with a 16-gauge shotgun can remove all the harpy eagles and less motile primates within 10 kilometers of a camp in a year, and thousands of people have done just that. Protected preserves are the only hope for such animals, and the governments of the Amazon are setting aside land for this purpose. The proper size for these refuges is now an active area of research.
The trees are another story. The contemporary reality is that much of the Amazon basin will be turned into pasture as people clear land for cattle grazing. The only hope for trees and perhaps for other plants and insects probably lies in the development of wise uses: ways to generate cash flow from the remaining forest that inflict no more disturbance than the rain-forest species are accustomed to. Perhaps parts of the forest could be set aside for vacation retreats or retirement communities or for industries that manufacture products that do not require enormous amounts of power and would not pollute the ecosystem. History does suggest that parts of the Amazon can be exploited productively without causing mass extinction, but wise use must be the overriding theme.
Paul A. Colinvaux, author of several books on ecology, has been professor of zoology and anthropology at Ohio State University since 1972. A native of Great Britain, he obtained bachelor's and master's degrees at the University of Cambridge before moving to the U.S. and earning a Ph.D. in zoology from Duke University in 1962; he went to Ohio State in 1964. When he is not engaged in his work, Colinvaux enjoys accompanying his wife, a coral reef biologist at Ohio State, on her diving expeditions.
about the rainforests and other tropical habitats by reading the following books and videos from The Stevenson Press, Inc.:
A Walk in the Rainforest
by Kristin Joy Pratt; hardcove
Wonders of the Rain Forest (Learn-About Books)
by Janet Craig and S.D. Schindler; paperback_
Into the Rainforest: One Book Makes Hundreds of Pictures of Rainforest Life (The Ecosystems Xplorer)
by Nicholas Harris; hardcover
Journey of the Red-Eyed Tree Frog
by Tanis Jordan and Martin Jordan
Journey Through a Tropical Jungle
by Adrian Forsyth; school & library binding
Jungle (Eyewitness Books)
by Theresa Greenaway and Geoff Dann; hardcover
This Place Is Wet (Imagine Living Here)
by Vicki Cobb and Barbara Lavallee; paperback
The Amazon Rain Forest and Its People (People and Places)
by Marion Morrison; hardcover
365 Days of Nature and Discovery: Things to Do and Learn for the Whole Family
by Jane Reynolds, et al; hardcover
Lessons of the Rainforest
by Suzanne Head and Robert Heinzman; paperback
Tropical Rainforests: Latin American Nature and Society in Transition
by Susan Place, editor;
Inside the Amazing Amazon
by Don Lessem and Michael Rothman; hardcover
Nature's Green Umbrella: Tropical Rain Forests
by Gail Gibbons; hardcover
by Mike Tidwell; hardcover
Life in the Rainforest
by John Erbacher and Sue Erbacher; hardcover
The Tropical Rainforest: A World Survey of Our Most Valuable Endangered Habitat with a Blueprint for Its Survival
by Arnold Newman;hardcover
Borneo Log: The Struggle for Sarawak's Forests
by William W. Bevis; hardcover
Earth's Vanishing Forests
by Roy A. Gallant; school & library Binding;
by Adrian Forsyth and Kenneth Miyata; paperback
Earthly Goods: Medicine-Hunting in the Rainforest
by Christopher Joyce; hardcover
And Then There Was One: The Mysteries of Extinction
by Margery Facklam and Pamela Johnson; paperback
The Fate of the Forest: Developers, Destroyers and Defenders of the Amazon
by Susanna Hecht and Alexander Cockburn; paperback
Nomads of the Dawn: The Penan of the Borneo Rain Forest
by Wade Davis, et al; paperback
The Last Rain Forests: A World Conservation Atlas
by Mark Collins; hardcover
The Conservation Atlas of Tropical Forests: The Americas
by Caroline S. Harcourt and Jeffrey A. Sayer; hardcove Animals in Peril: How 'Sustainable Use' Is Wiping Out the World's Wildlife
by John Arthur Hoyt; paperback
Alternatives to Deforestation: Steps Toward Sustainable Use of the Amazon Rain Forest
by Anthony B. Anderson; hardcove
The Atlas of Endangered Animals (Environmental Atlas Series) by Stephen Thomas Pollock; hardcove
Here Is the Tropical Rainforest
by Madeleine Dunphy and Michael Rothman; hardcove
The High Frontier: Exploring the Tropical Rainforest Canopy
by Mark W. Moffett; paperback
Plants of the Tropics (Plant Life Series)
by Susan Reading; hardcover
The Primary Source: Tropical Forests and Our Future (Updated for the 1990s)
by Norman Myers; paperback
Rain Forest/With Magnifying Glass (Nature Search)
by Paul Sterry, et al; hardcover
Biology and Conservation of Sea Turtles: World Conference on Sea Turtle Conservation
by Karen A. Bjorndal; paperback
by Edward O. Wilson; paperback
Can Tropical Rainforests Be Saved?
Amazon Land of the Flooded Forest
National Geographic; VHS tape
Really Wild Animals: Totally Tropical
National Geographic; VHS tape
Tropical Rain Forest
Science Museum; VHS tape
Help Save the Planet Earth
The Rainforest (The Earth at Risk Environmental Video Series)
Exploring the Rain Forest (Learning Adventures)
Redbook Learning; VHS tape
You Can't Grow Home Again
(3-2-1 Contact : Extra); VHS tape
The Future of the Past (The Infinite Voyage)
Infinite Voyage; VHS tape
The Keepers of Eden (The Infinite Voyage)
Infinite Voyage; VHS tape
Hawaii Strangers in Paradise
National Geographic Video; VHS tape