Conservation biology in the U.S.-Mexican border region.

• Author: Van Schoik, Rick

The U.S.-Mexican border region has the highest rate of species endangerment in the United States. Some 31 percent of the species listed as endangered by the U.S. Department of Interior are found in the region. On the Mexican side of the border, 85 species of plants and animals are endangered. Not surprisingly, the threats to these species are exacerbated by the fact that the ecosystems in this region are split by a political boundary that greatly complicates conservation efforts.

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The area along the U.S.-Mexican border has seen extraordinary population growth, and the resulting residential and industrial sprawl along the border can evoke a doomsday vision for the entire strip from the Pacific to the Gulf of Mexico. Already, habitat loss is estimated at 2.5 hectares (more than 6 acres) per day within Tijuana alone.

Last summer a coalition of U.S. and Mexican conservation biologists and other experts (the Southwest Consortium for Environmental Research and Policy) met to discuss possible ways of responding to this mounting border crisis. Well aware that the most important principle of biodiversity conservation is the need to protect the largest possible intact landscapes, we focused on identifying ways in which protections could be established that, in effect, crossed the border--regardless where the fences or guards might stand--to encompass whole ecosystems.

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Establishing effective cross-border policies is not easy. While nations can readily agree to conserve migrating species in their territories, as when Mexico signed on to the United States' Migratory Bird Treaty Act to protect migrating birds half a century ago, protecting adjacent prime natural areas proves much more difficult. Designed to stop humans from freely crossing, borders also stop other species. Since 9/11, the U.S.-Mexican border has been further bolstered by both the Department of Homeland Security (DHS, which was formerly divided into the customs, border patrol, and immigration agencies) and the still somewhat-secret Joint Task Force Six (JTF-6, a multi-service command charged with providing counter-drug-trafficking support).

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These agencies' efforts and physical infrastructure have done significant damage to wildlife habitats. Their use of sensor fields, roads, and triple fences up to 50 meters deep create erosion and dust. The physical...