A highly politicized issue, migration is often discussed in terms of economics, nationality, and culture. Yet this perspective leaves out a crucial factor: the environment. Environmental degradation is a frequent cause and consequence of human migration, particularly in developing countries. At an event sponsored by the Environmental Change and Security Program on October 10, 2007, World Wildlife Fund's (WWF) Judy Oglethorpe, lead author of People on the Move: Reducing the Impact of Human Migration on Biodiversity, was joined by three other experts to discuss the relationship between migration and biodiversity. Drawing lessons from case studies in the Galápagos Islands and Southern Bahia, Brazil, they offered recommendations for mitigating migration's harmful effects on the environment.

Migration: Pushes and Pulls

According to the authors of the report, who also include Jenny Ericson, Richard Bilsborrow, and Janet Edmond, migration can disrupt ecological processes and lead to loss of species, habitats, ecological connectivity, and long-term residents' livelihoods. Migration can also introduce invasive species, and migrants' unsustainable use of resources can degrade the environment in their new homes. Migration threatens ecosystems because it can rapidly disrupt settled patterns of resource use and human interaction with the environment. "Unlike population growth due to fertility, migration can happen incredibly quickly….If you look at the number of people, for example, who fled from Rwanda during the genocide in 1994, that happened within the space of a week or so," said Oglethorpe.

Migration is also significant because it can occur on a vast scale. Three million people migrate across international borders each year, and internal migration may be 100 times greater, said Oglethorpe. Furthermore, although many people assume migration is predominantly a rural-to-urban phenomenon, rural-to-rural migration—which is also common—has the greatest negative impact on the environment.

While a person's decision to move always depends on a particular set of social, political, and economic circumstances, several common factors can "push" people away from their homes or "pull" them to new areas. "The push factors that we're most concerned about are scarcity of land or lack of access to land. Sometimes it occurs because populations are growing through natural growth. Sometimes it's because people have moved in and pushed people off their prime land. This happened a lot in colonial times and it continues to happen," said Oglethorpe, who identified poverty, natural disasters, and rites of passage as other important push factors.

Pull factors, on the other hand, include the hope for a better life, better employment prospects, greater access to markets, and safety. However, the same factor can have very different effects on migration. For instance, the presence of roads in a relatively stable country could be a pull factor because people want easy, reliable access to markets. But in a war-torn country, people might flee from areas close to roads to escape violence. Oglethorpe stressed that developing successful interventions that address the needs of migrants and ecosystems requires understanding the specific combination of push and pull factors in a given situation.

Cocoa, Migration, and Biodiversity: A Case Study in Southern Bahia, Brazil

Keith Alger of Conservation International used the history of cocoa production in Southern Bahia, Brazil, to illustrate how patterns of agricultural production can link migration and environmental degradation. During the 1990s, Brazil was the second largest producer of cocoa in the world, although its share of the world market has since declined. In Brazil, cocoa production often shifts between areas due to cocoa's long production time—it takes about six years to mature, so farmers (who are typically internal rural migrants) often pursue other economic activities during the growth cycle.

"Cocoa grows in areas…in Africa, Latin America, and Asia that correspond very closely to what Conservation International calls ‘biodiversity hotspots,'" Alger explained. These hotspots are critical to their regional ecosystems, and are often negatively affected by migratory cocoa production. In Southern Bahia, farmers moved into new areas in pursuit of fertile soil. Significant swaths of forest, separated by large deforested areas, still host high numbers of species unique to the region—but these fragmented ecosystems are strained by the environmental degradation caused by agriculture.

In the late 1990s, the price of cocoa declined, a disease afflicted the cacao trees, and cocoa workers were laid off—many of whom migrated away from the forested areas of Southern Bahia, said Alger. "They went to shanty towns in the urban centers of the region, they went to shanty towns outside the region—El Salvador, Sao Paolo, Rio de Janeiro—or they went to shanty towns around the tourism centers on the coast." Meanwhile, increased soybean production caused an influx of migrants into other areas of Brazil.

Brazil's experience illustrates the dangers of depending on a single crop for survival. If the crop ceases to be profitable, the subsequent migration of workers seeking new economic opportunities can deplete the ecosystems of the destination areas and cause tension in those communities. Realizing this, Brazilian NGOs have been working to encourage crop diversity so farmers' livelihoods are not tied to the success of a single crop.

Alger noted that the growth of biofuels is likely to pose challenges to biodiversity and environmental conservation around the world, as cocoa production has done in Brazil. He believes that collaboration with industry is essential to ensuring the preservation of unique ecosystems. "In the future," he said, "our main concern is working with the consuming industries that are going to be purchasing the oil palm, soy beans, switchgrass, and other biofuel inputs so that we can work at the scale that those will be sourced and inform them on how that production can occur without further expanding into areas critical for biodiversity."

Progress on Protecting the Galápagos

As managing director of WWF's Galápagos Program, Lauren Spurrier has helped promote and analyze Ecuador's efforts to protect its Galápagos Islands, where the vibrant eco-tourism industry has dramatically increased migration. While the boom has increased the human footprint in the islands, Spurrier stressed that the situation is hopeful: "There have been negative impacts on biodiversity, but by and large, Charles Darwin would still recognize many of the places he visited 170 years ago."

In 1959, the Ecuadorian government created the Galápagos National Park, protecting 97 percent of the islands' land area; in 1978, UNESCO designated the Galápagos a World Heritage Site. "The other very important accomplishment has been the Galápagos Special Law in 1998 that created the marine reserve, banned migration to the island, and…bans industrial fishing in the marine reserve," said Spurrier. Artisanal fishermen have helped the government discourage the industry from fishing for tuna in the reserve, which, at approximately 50,000 square miles, is the third largest in the world. Another significant step is the recent election of a conservation leader as governor of the Galápagos. And the Isabela Project, which focused on the eradication of introduced species on the island of Isabela, was a remarkable success, Spurrier noted.

With 95 percent of its original biodiversity intact, the Galápagos is a "huge opportunity," said Spurrier, although significant challenges remain. The ban on migration has not been effectively enforced and the human impact continues to grow. Sustainable development of the islands is necessary if the eco-tourism industry is to thrive in the long term. Waste management is one problem confronting the Galápagos Islands: Islanders often dispose of trash by burning it, and Spurrier spotted a hazardous drum of benzene in one island's garbage dump. She is working to establish a sustainable system of waste management that will not harm the islands' environment.

Overall, Spurrier believes the prospects for the Galápagos are good because "the government has created the economic and political clout necessary to protect the islands, and at the same time [the islands are] generating a lot of money into the local- and national-level economies."

Digging Deeper

Brown University's Michael White praised the authors of People on the Move for recognizing the complex links between poverty, migration, population pressures, natural disasters, civil conflict, and environmental degradation. "There's a sub-theme here that the well-being of individuals is very important," he said. Oglethorpe echoed this sentiment: "We recognize that many migrants move because they're forced to—because of persecution, because of conflict, because of poverty—and so we have to have a human face when we approach this problem."

Around the world, urbanization continues, armed conflicts trigger large-scale internal and international migration, and population growth increasingly strains natural resources. People on the Move describes many of the interventions that can help prevent or alleviate the environmental stress caused by migration. Understanding which interventions are most successful will be increasingly important in an age of growing—and more mobile—populations.

Drafted by Miles Brundage and edited by Rachel Weisshaar.