The Mesoamerican Biological Corridor

Map of Forest Preserves in Mesoamerica
dark green = current reserves, light green = developing reserves
scale: one pixel = five kilometers

Editor’s Note: Saving and restoring forest reserves and wildlife habitat is better done when these areas are connected. The concept of wildlife corridors has been around for about 20 years, but has found perhaps its most inspiring expression in the accomplishments in Central America. In this region, seven governments have agreed to coordinate their efforts to encourage a huge system of interconnected parks, reserves and wildlife corridors that literally link North America to South America.

Not only is the scale of this undertaking unusual, but the means whereby Central American biological corridors are being established are innovative and sustainable. Costa Rica provides a particularly excellent case for how biocorridors can be encouraged using a variety of means; through tax incentives, preservation easements, education, decentralized administration, partnerships with international organizations, as well as outright land purchases.

This personal account by Jack Ewing, a noted wildlife author as well as owner of the Hacienda Baru Wildlife Refuge in southwest Costa Rica, offers a comprehensive look at how the Mesoamerican Biological Corridor came about. Also noted are specific ways Costa Rican’s have tackled the challenge of land preservation, a challenge they have met so successfully that forested land in Costa Rica has more than doubled in the last 20 years. Hacienda Baru, for example, was completely deforested from the beach to the highlands only 30 years ago. Today it comprises one of the richest wildlife refuges in the world. – Ed Ring

I wouldn’t call Lobo mean.

He was more crazy than mean.

Any animal that came across his path would put him in a frenzy whether it be a cat, opossum, iguana, coati or another dog. He’d get wild-eyed, froth at the mouth and chase it down wherever it went, through brush, water, into holes and over embankments. He really went nuts, and when he caught em he killed em, always.

Lobo was off somewhere that day when we spotted the young capuchin monkey crossing the pasture. I remember thinking how out of place it looked 200 meters from the nearest tree. We stopped working and watched as the monkey skip-loped by. It paused briefly to look at us, then moved on in its awkward gait. I caught sight of the charging dog at the same moment I heard Osvaldo shout. “Lobo, no!! Lobo, quitase, no, no!! Lobo quite hihweputa.” But Lobo didn’t stop.

Lobo ignored his master’s call and kept barreling toward the capuchin. I shuddered in anticipation of the carnage. That big dog hit the monkey full force, but it seemed as if the primate bounced into the air and came down on top of the dog. A flurry of squeals, flying fur and blood ensued. The monkey rode Lobo like a bronco, gouging his eyes, biting his ears and head and scratching his flanks all at the same time. I can only describe the dog’s voice as a scream, a frantic plea for mercy. He bucked, twisted and rolled on the ground trying to rid himself of the torment. The fight ended abruptly. The capuchin jumped clear of the terrified dog who took off wailing and crying until he reached Osvaldo’s house, where he crawled into a space under the floor, covered his face with his paws and whimpered. Lobo never chased another animal as long as he lived.

Hacienda Baru Logo

That was back in 1973 when Hacienda Baru was a cattle ranch. There was an estuary with a mangrove forest near the mouth of the Baru River, two small wetland forests on the coastal plain and a large primary rain forest in the highlands. These islands of vegetation were all separated from each other by at least half a kilometer of pasture. Small troops of white-faced capuchin monkeys (Cebus capucinus) inhabited each of the lowland forests and several larger troops lived above in the primary rain forest. At some point during their physical development the mere presence of young male capuchins became intolerable to the troop’s dominant male, who then expelled them from their little forest home. Their only hope for survival was to reach the larger primary rain forest, but to do that these post-adolescents had to run across pastures.

That year I planted trees as living fence posts. I was pleasantly surprised to see that once these tree-posts reached a height of a few meters the monkeys began using them as pathways rather than crossing open pastures. I planted more and longer lines of trees which were later used by a variety of arboreal fauna including monkeys, sloths, kinkajous, opossums, iguanas, and olingos. I still wanted to raise cattle and horses, but I loved seeing fauna too. As my fascination with tropical nature expanded so did these wildlife corridors.

By 1990 there were five forested corridors on Hacienda Baru where a monkey could travel from the beach to the highlands without leaving the trees. That was the year I sold all the cattle. In 1995 Costa Rican President Jose Maria Figueres signed the decree creating Hacienda Baru National Wildlife Refuge. By that time sloths, pacas, anteaters and even collared peccaries were seen in the lowlands, and spider monkeys had migrated along neighboring forested corridors from distances of over 17 kilometers to settle at the refuge. Environmental groups began working on local, regional, national and even international biological corridors which facilitated the migration of wildlife and enhanced biodiversity. Now the monkeys don’t have to descend to the ground unless they want to.

Central American Rainforest Canopy
Central American Rainforest Canopy



The concept of biological corridors was born in Florida where environmentalists were searching for solutions to the shrinking and fragmentation of wildlife habitat. The creation of corridors of natural vegetation between larger reserves was seen as a way to allow wildlife more freedom of movement and access to a wider variety of natural vegetation.

When groups of any particular species are confined in isolated patches of habitat with limited area, they become subject to a variety of environmental stresses. The diversity of food plants may not be sufficient to provide sustenance through all of the seasons. Isolated populations of animals with limited gene pools tend to become inbred, resulting in loss of fertility, vigor and resistance to disease. Social pressures may increase, as was the case with the young capuchin expelled by the dominant male.

In the 1980s researchers in Brazil, Florida and elsewhere determined that as the size of a parcel of rainforest increases, the biodiversity it harbors also increases but by a factor higher than the increase in area. For example, a forest reserve of 1000 hectares might have 100 species of beetles, whereas one of 2000 hectares might have 300 species. By doubling the size of the reserve, the biodiversity could triple. Please note that these are not actual figures. The results of studies vary and scientists don’t agree on any one formula for the relation between parcel size and biodiversity. I use them here for the sole purpose of illustrating the principle.


If we take this idea a step further, simple logic tells us that one reserve of 1000 hectares, separated from another of 2000 hectares by 20 km of fragmented habitat, will increase considerably in biodiversity if we can connect the two together with a wide swath of natural vegetation — a biological corridor. But how wide?

This frequently asked question doesn’t have a simple answer. As we saw in the example of Hacienda Baru a single line of trees served as a corridor for several species of arboreal mammals, and certainly enhanced their living conditions, chances of survival and populations, but I doubt if it would do much to increase biodiversity in the forest reserves at either end of the line. For a corridor to be truly effective and biologically beneficial to the reserves it connects, it needs to be wide enough to permit the safe passage of most species of fauna, large and small. This includes everything from large predators to tiny litter frogs. It must be wide enough to provide an environment conducive to the existence of wide varieties of epiphytes, fungi, molds, insects and microorganisms. But how wide is that?

A biologist friend once put it this way: If there are houses anywhere near the corridor, there will be house cats, which will kill any small animal or bird they can catch. House cats seldom venture more than 400 meters from home. Therefore, 800 meters is the absolute minimum width for a fully functional biological corridor, but of course, wider is better. Not only house cats, but predators of all kinds, learn that the corridor is a narrow stretch between larger reserves, and this bottleneck is the perfect place to lie in ambush. Prey animals quickly learn of the danger and are wary of crossing. Ideally, a corridor would be several tens of kilometers wide, but this is not always possible. I think it is important to remember that even if it is less than 800 meters wide, any corridor is better than no corridor. A single line of trees is better than an open pasture.

Aerial View of Hacienda Baru, Costa Rica in 1972
Hacienda Baru, Costa Rica, in 1972
The entire coastal lowlands have been deforested


By the early 1990s most biologists agreed that biological corridors could be a useful tool for increasing biodiversity and enhancing the ecology of large protected areas.

It was about that time when a vision emerged of an immense biological corridor that would connect the forests of southern Mexico to those of all the rest of Central America and eventually reach the Panama Canal, a biological bridge between continents.

The visionary who came up with this concept was Archie (Chuck) F. Carr III, and he called his idea the “Path of the Panther,” in recognition of the Florida Panther (Felis concolor,) also known as cougar, mountain lion and puma. These majestic cats are symbolic because they survive throughout the region wherever sufficient habitat remains.

In order to fully understand the origins of the proposed biological bridge between North and South America, we need to look briefly at the origins of another bridge, Central America itself. When the geological processes that culminated in its creation began, more than 50 million years ago, the two American continents were separated by several thousand kilometers of ocean and a channel over 2000 meters deep. The movements of five different tectonic plates modified the earth’s crust bringing the two enormous land masses closer together, lifting the sea floor and fomenting volcanic action.

By fifteen million years ago the deep water channel between the American continents had risen considerably and significantly modified ocean currents. The diminishing of ocean currents brought many consequences including the alteration of global climate. By ten million years ago, an ice age cycle of approximately 100,000 years was well established and was causing sea levels to rise and fall during interglacial and glacial periods, respectively.

Ministerio de Ambiente Recursos Naturales Logo

By eight million years ago Central America looked like an archipelago during glacial periods. At that time two species of giant ground sloths swam about 60 kilometers to become the first South American mammals to reach North America. By three million years ago the gap closed, completing the land bridge and bringing on a tremendous biological upheaval as flora and fauna traveled in both directions, mixed, adapted, competed for niches and gradually settled into an ecological balance as they populated both continents. A mere 10,000 years ago humans arrived, and within a millennium, most of the large game animals, such as mammoths, toxodonts, giant bison, giant ground sloths and others were hunted to extinction.

By 2000 years ago humans had domesticated many species of plants and animals, and agriculture had replaced hunting and gathering as the main source of food. It is only logical to believe that indigenous peoples deforested vast regions of Central America. In fact, deforestation has been postulated as a contributing cause to the fall of the great Maya Civilizations over 1000 years ago. When Europeans arrived in the western hemisphere, the population of Central America was about the same as it is today, 40 million people. It is simply not possible for that many people to live in an area of 750,000 square kilometers without destroying vast amounts of natural habitat. Nobody knows with any accuracy the extent of that wave of deforestation, but it was probably comparable to that of the 20th century.

Small pox and other European diseases brought an end to the deforestation. The population of Central America plummeted, and Mother Nature reclaimed the land. Enormous tracts of land throughout the region remained relatively undisturbed for more than four hundred years, until Central American populations again expanded to a level where deforestation became a significant threat to biodiversity. By 1980 the Central American tropical forests had been severely fragmented by agriculture, cattle ranching and urbanization. Olga F. Linares in the foreword of Central America, A Natural and Cultural History, stated it very well, referring to the area to be influenced by the Path of the Panther as: “…a biological corridor that took more than 60 million years to develop and is taking less than a century to be destroyed.”

Young Girl Planting Tree
a young tree planter adds another


At the end of the 1980s, when the Wildlife Conservation Society and the Caribbean Conservation Corporation took on the challenge of promoting the Path of the Panther Biological Corridor, the project was, and still is, seen as the reconstruction of ecosystems throughout the region. The remaining forested areas, which were, for the most part, confined to national parks, wildlife refuges, forest reserves and other protected areas, contained a very high percentage of the biodiversity. The challenge was not only to halt the destruction of these tropical forests, but also to restore swathes of natural vegetation between them, connect them together biologically, and create an effective and sustainable system of environmental protection.

Because of the volcanic origin of Central American soils and continued volcanic activity the restoration of natural forests is feasible. Fortified by an invisible blanket of constantly settling, nutrient-rich volcanic dust, the land, when left to the whims of Mother Nature, will sprout into a mass of natural vegetation that quickly evolves into secondary forest. This, in turn, creates a suitable environment for a multitude of organisms which almost immediately begin migrating into the newly reclaimed habitat. In places like the Amazon, plagued with nutrient poor soils, such a project would probably not be possible.

The name “Mesoamerican Biological Corridor” (MBC) was coined in 1992 at the United Nations Conference on Environment and Development in Rio de Janeiro, and the importance of regenerating natural habitat and connecting the natural areas of the region was recognized as a top priority.

Belize Biocorridor Partner Logo

A treaty signed by the governments of Mexico and all the Central American nations, at a 1997 summit meeting, officially established the corridor. The document describes the Mesoamerican Biological Corridor as:

“…a system of territorial organization, comprised by the interconnection of the Central American System of Protected Areas and surrounding buffer and multiple use zones, that offers a combination of environmental goods and services to the Central American and world community, and promotes investment in the conservation and sustainable use of natural resources; all by way of ample social consensus, with the objective of contributing to the improvement of the quality of life of the inhabitants of the region.”

The Central American Commission on Environment and Development (CCAD) was charged with coordinating the project at a regional level. Most of the signatories formed commissions responsible for implementing the project at a national level. Soon thereafter, funding became available from a number of sources including the United Nations Environment Program, United Nations Development Program, World Bank, US AID, European Community and others.

Hacienda Baru Wildlife Refuge in Costa Rica
Hacienda Baru Wildlife Refuge, Costa Rica, 2005
the forest is completely restored


Costa Rica has taken the biological corridor challenge very seriously. The government formed the National Commission for the Mesoamerican Biological Corridor in 1997. A strategy for the implementation of the project was elaborated. It was decided that the creation of a number of local corridors was more feasible than one national corridor.

Costa Rica’s commission determined that the responsibility for the creation of local biological corridors would be delegated to rural communities and non governmental organizations (NGOs,) with the national commission to coordinate amongst these groups.

Early on it was recognized that strong, well organized community organizations were of paramount importance to the accomplishment of the Costa Rican sector of the Mesoamerican Biological Corridor. The strategy elaborated by the commission was:

Identify the zones where corridors are needed

Identify NGOs within those areas that are willing to take on a corridor project

Train and strengthen these groups

Provide local organizations with the tools to accomplish their objectives.

The National System of Protected Areas (SINAC) determined priority areas for the creation of corridors. The MBC commission with the help of the National University and the World Conservation Union (IUCN,) began looking for NGOs capable of creating local biological corridors. In many cases, this meant first teaching the organization what a biological corridor was, why it was important and how it would help local communities, and then motivating them to take on the project.

In 1999 the World Wildlife Fund financed a campaign to publicize the mesoamerican biological corridor and create public awareness about its importance and the benefits it would produce. Financing for NGOs and corridor friendly local projects became available from several international organizations of which the United Nations Development Program (UNDP) was the most active. There were differences between corridors, but many of the same tools were used in different places and by different groups to create local corridors.

Youth Environment Group in Woods
a reforesting tradition begins

Teaching and Motivating –

When building a house, the first step is laying a solid foundation. Likewise, the construction of a corridor begins with environmental education. In order to change the way people relate to their environment it is important to convince the youth.

Once the younger generation has been enlightened the general public attitude about the environment begins to change. I remember a phone call from an irate father accusing a local environmental group of “poisoning children’s minds.” When questioned further, it turned out that the man’s eight year old daughter would not allow him to poach or consume the eggs of endangered marine turtles, something he had done all of his life. Though he didn’t change his mind, he did accede to his daughter’s wishes. In some areas, local NGOs have been carrying on environmental education for 15 years. The first students to receive the material have now matured, and some have become leaders in their communities.

Environmental education is important for adults as well as youth. Many people would like to protect the environment, but feel helpless to do so. Government enforcement of laws is often weak or nonexistent. One solution to this problem in Costa Rica is a program which makes it possible for private citizens to become voluntary game wardens. In order to acquire the official identification card, they must attend two training workshops and pass an exam on environmental law. These non salaried game wardens have almost as much authority to enforce environmental laws as a full time park ranger. Many property owners have acquired this status in order to protect their own property from poachers. The program has worked well in some places and not in others. The determining factor seems to be the presence of strong NGOs that sponsor the training programs and follow up with refresher courses and motivation for the volunteers.

Honduras Biocorridor Partner Logo

At least one NGO has taken this idea one step farther and sponsored training and motivational workshops for local police officers. Many times police in rural communities are ignorant with regard to environmental legislation. When they are given basic training and motivation and backed up by a group of volunteer game wardens, they become a very positive force in controlling environmental abuses and enforcing laws.

The strengthening of local NGOs goes hand in hand with education. Environmental awareness alone doesn’t accomplish much when community organizations are weak and poorly financed. The UNDP has taken the lead in funding projects that fortify communal groups, women’s groups and indigenous groups. Once organized, trained and motivated, many of these groups have gone on to play key roles in the creation of biological corridors. Without their support the accomplishment of project objectives would be extremely difficult.

Making Conservation Profitable

Simply educating, organizing and strengthening rural community organizations is not enough. The people must benefit tangibly, and in the short term, from a healthy natural environment. Everyone has to make a living, and conservation will not work on a large scale if people don’t profit from it. The two main ways in which this has been accomplished is through Environmental Service Payments and Ecological Tourism.

Paying for Environmental Services –

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Monkeys are made of Chocolate Book Cover
Monkeys are made of Chocolate
by Jack Ewing

In Costa Rica, Environmental Service Payments are cash incentives given to people who protect environments that provide services for people. Woody plants remove carbon from the atmosphere, tie it up in wood fiber and release oxygen. Therefore people who plant trees or forgo development and leave their property forested, are providing a service for everyone: air-cleaning and oxygen production. The Costa Rican Environmental Service Payments program pays these people for that service.

Funds to pay tree planters are provided by a fuel tax. That way people who burn fossil fuels – everyone who drives a car – which release carbon into the atmosphere, end up paying for its removal. At present, the environmental service payment for forest conservation is about $60 per hectare per year, not enough to make anybody rich, but certainly enough to discourage deforestation for the purpose of raising cattle.

Another type of Environmental Service Payment charges water users a fee for the protection of the watershed where their potable water originates. This program is relatively new and has not yet been widely implemented, but it is certain to become an important method of environmental protection in the future.

Ecological Tourism –

When done well, ecological tourism can be a very effective means of making conservation pay for itself. In Costa Rica tourism is the number one foreign exchange earner, and ecological tourism is the most important sector. Though the country has close to a thousand kilometers of coastline, more tourists visit the national parks and wildlife refuges than visit the beaches. In southwestern Costa Rica, where I live, few people doubt the importance of wildlife and rainforest to the local economy. Where 20 years ago there was nothing but cattle ranches, agriculture and scattered patches of forest, today there are seven national wildlife refuges, one national park and at least 30 private nature reserves.

The many protected areas are the biggest tourist attraction in southwestern Costa Rica. Ecological tourists and bird watchers visit the region year after year, do no damage to the environment, purchase goods and services and take away only their memories. As a general rule, ecological tourists tend to respect local customs and cultures. Everybody wins including Mother Nature. In 1976, when I first prohibited hunting at Hacienda Baru, less than two percent of the local population supported me. Today the figure is more like 85%. A big part of the difference is that today rainforests and wildlife help people make a living.

El Salvador Biocorridor Project Logo
El Salvador

Land Purchases –

Corridor projects that involve very large forested areas have sometimes used a strategy of raising money to purchase large tracts of land, which are then given some sort of permanent official protection. This method works well when the area to be protected is sparsely inhabited. The land purchased may be protected in one of three methods:

Donation to the national parks system and declaration as a national park

Declaration as a national wildlife refuge which remains the property of the local NGO promoting the project

The placing of environmental easements on the purchased properties. This may be done in conjunction with the first two methods of protection.
These methods give both security and permanency, so that all parties involved are confident that the land use will not be changed.

An example of a corridor where this strategy is being applied is the Osa Biological Corridor, which will connect the Corcovado National Park in the Osa Peninsula to the Piedras Blancas National Park on the mainland. Conservation International and The Nature Conservancy are some of the international organizations that help raise money for land purchases.

Nicaragua Biocorridor Project Logo


In the last two years the Costa Rican commission for the Mesoamerican Biological Corridor has given financial assistance to local corridor projects for the monitoring of species of flora and fauna within their respective corridors. At this early stage available data is insufficient to come to any conclusions, but on a subjective level we can make some general observations. As my personal experience has been with the Path of the Tapir Biological Corridor (PTBC,) the following comments relate to that particular southwest Costa Rica project:

Biology and Ecology:

Spider monkeys and howler monkeys that have long been absent from many parts of the PTBC are migrating along corridors and establishing breeding populations where they haven’t been observed in over 50 years.

Squirrel monkeys, a species formerly completely absent from the area have now moved into the corridor and at least one reproducing group is well established on a wildlife refuge.

White-lipped peccary are moving back into the region where they have been locally extinct since the 1960s.

In three years of Audubon Society sanctioned Christmas Bird Count, the PTBC count has increased steadily: 2003 — 340 species; 2004 — 383 species; 2005 — 395 species.

Populations of species such as pacas, agoutis, coatis, collared peccary, five species of felines, great curasows have all increased noticeably in the last ten years.

The area of forest cover has more than tripled in the last thirty years.

Costa Rica Biocorridor Project Logo
Costa Rica

Social Organization:

126 voluntary game wardens have been trained and approved.

32 schools receive environmental education

7 National Wildlife Refuges and more than 30 private nature reserves have been established since 1995.

8% of the land area is protected by Environmental Service Payment Contracts

Ecological Tourism has replaced ranching and agriculture as the number one economic activity.

Problems and Threats:

The value of land has increased to a level where only foreigners can afford to own property in the region and local Costa Ricans who were once property owners are being displaced or have become employees of the new land owners.

Due to weak or nonexistent enforcement of environmental laws developers are able cut illegal roads through rainforests, level off home sites and cause serious environmental damage with few if any consequences.

Panama Biocorridor Project Logo

Real estate developers with little respect for tropical ecosystems, have seemingly unlimited funds with which to destroy natural areas, while local environmental groups who wish to conserve habitat are severely under-funded.

Many property owners would like to inscribe their properties in the Environmental Service Payment program but limited funding has prevented extending the incentives to everyone who is conserving forests.

The original projection for financing for the MBC by international funding institutions such as UNDP was 10 years, of which eight have already elapsed. Many projects have reached a level where they are effective but not yet sustainable. If funding dries up in the next few years these projects will collapse.

Tapir Sign


Central America forms a bridge between north and south America which throughout its three million year history has served as a natural corridor connecting the two continents biologically. In the last century much of that corridor has been destroyed. Biologists have determined that biological corridors are an effective method of conserving and enhancing biodiversity in fragmented ecosystems.

The idea that the tropical forests of Central America could be reconstructed and joined together in a corridor was originally promoted by the Wildlife Conservation Society and the Caribbean Conservation Corporation. The project was called the Path of the Panther. Governments throughout the region later adopted the project and changed the name to the Mesoamerican Biological Corridor (MBC.)

Responsibility for regional coordination was given to the Central American Commission on Environment and Development (CCAD) and headquartered in Managua, Nicaragua. Implementation of the project in each country became the responsibility of national MBC commissions. Each of these commissions works in a different manner. Some have been very effective and others less so.

Costa Rica is the only country that has elected a strategy of working with community and environmental organizations to create a chain of local biological corridors. As a result Costa Rica has experienced a higher level of success in establishing the MBC than most other countries in Central America. Nevertheless, environmental destruction by real estate developers poses a serious threat to the environment and the government seems to be incapable or unwilling to control it.

In the final tally, the Mesoamerican Biological Corridor has made significant advances, but much more is needed. If funding from international agencies is diminished or discontinued in the near future, it could mean the death of the reconstruction of the Central American biological corridor.

For further reading:

Central America: A Natural and Cultural History

Anthony G. Coats, Editor, Yale University Press, New Haven and London

Collapse: How Societies Choose to Fail or Succeed

Jared Diamond, Viking Penguin Group, New York

The Sixth Extinction

Richard Leakey, Doubleday, New York

New Revelations of the Americas Before Columbus, 1491

Charles C. Mann, Alfred A. Knopf, New York

Online References:

Central American Commission on the Environment and Development (Spanish)

Pro Diversitas (Spanish)

United Nations Development Program

Mesoamerican Biological Corridor (English and Spanish)

Path of the Tapir Biological Corridor (Spanish)

Web site of Hacienda Baru National Wildlife Refuge

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