US-Mexico Border Barriers Threaten 1,500 Plant and Animal Species

“Scientists are not activists. It goes against their grain and training to make political statements,” says Robert Peters, a scientist himself and the senior southwest representative at the conservation nonprofit Defenders of Wildlife. “So when 2,700 of them sign a letter opposing the [US-Mexico] border wall, you know the wall is an ecological disaster.”

Peters is the lead author of a paper (pdf) that appears today (July 24) in the journal Bioscience documenting the ecological harms of fence and barrier construction along the 2,000 mile US-Mexico border over the past decade, and the further damage that would be incurred by Trump administration’s proposed continuous wall. The paper is co-signed by 2,700 scientists from 47 countries. “Fences and walls erected along international boundaries in the name of national security have unintended but significant consequences for biodiversity,” they write. In fact, according to Defenders of Wildlife senior scientist Jenni Miller, the border barriers threaten the health of 1,5000 species of plants and animals, including 62 endangered or vulnerable species.

National heritage and national security

“Debates about the border wall typically focus on immigration, economics and national security, but the harm to Americans’ natural heritage is an outcome rarely discussed,” says Jennie Miller. “Do we really want to trade our natural heritage for national security?”

It’s a rhetorical question, she says: There’s no need to make such a stark tradeoff. We could avoid hurting ecosystems “if we simply take care to consider and mitigate impacts to wildlife and their habitats when implementing border infrastructure and operations.”

Instead, according to Miller and her colleagues, the US is bypassing environmental laws to build barriers. As a result, they construction undergoes no review processes or ecological assessments, and will end up degrading and fragmenting environments that conservationists and governments have invested a lot of time and money in. “Like any large-scale development, construction of the wall and associated infrastructure, such as roads, lights, and operating bases, eliminates or degrades natural vegetation, kills animals directly or through habitat loss, fragments habitats (thereby subdividing populations into smaller, more vulnerable units), reduces habitat connectivity, erodes soils, changes fire regimes, and alters hydrological processes (for example by causing floods),” the paper explains.

The construction endangers not only plants and animals, but scientists themselves. Both American and Mexican scientists have been harassed, deterred, and detained at gunpoint by Department of Homeland Security agents while going about their business of studying local flora and fauna, Peters explains.

As of 2017, the Department of Homeland Security had constructed more than 650 miles worth of barriers along the border serviced by nearly 5,000 miles of roads, and thousands of miles of undesignated routes created by off-road patrol vehicles. All that action is ecologically harmful, according to the paper. The scientists write, “Human activity, light, and noise associated with the wall further displace wildlife, making additional habitat unavailable.”

Sunk costs, lost

Consider the example of the Santa Ana National Wildlife Refuge on the Rio Grande, for example—the last and best remnant of riparian forest in the region. Only three acres of this unique forest, adjacent to a river, still stand where once there were thousands of wooded acres. “It’s like an environmental museum,” Peters says.

Last year, however, the Trump administration wanted to build a wall right through the reserve—which would have not only cut off passage for all migrating animals “except some lizards who could scramble over it,” Peters explains, but also caused flooding and drown creatures during rains. The wall would have also caused serious harm to the local community’s economy, which relies on the $30 million a year that eco-tourism brings in, he adds. Most notably, the action would have destroyed the last portion of this once-vast riparian forest.

Outcry over the proposal blocked the plan, and the Santa Ana reserve is now technically safe thanks to protestors who convinced their representatives to bar funding for a wall there when they passed a spending bill in March. But the adjacent National Butterfly Center won’t be protected.

The same appropriations bill that barred building on the 2,088 acre Santa Ana reserve allocated $1.6 billion to build 33 miles of barriers through the center, a state park, and other tracts of land in the national wildlife refuge system. That will fragment the dwindling wildlife habitat on the border and create around 6,500 acres of “no man’s land,” cutting off human access to nature and trapping wildlife when the Rio Grande floods.

The gray wolf and the jaguar

Nearly a fifth of the border area contains protected lands. It’s an ecologically rich terrain with six different climates and a wide array of animals that must traverse the territories. Physical barriers prevent or discourage animals from accessing food, water, mates, and other critical resources by disrupting migration and dispersal routes, the paper states.

For example, continuous walls could constrain endangered Peninsular bighorn sheep, block the reestablishment of already dwindling populations like the Mexican gray wolf and Sonoran pronghorn, cause decreased genetic diversity generally among the 350 species found there, including jaguars and ocelots, and raise extinction risks for all local creatures. Border barriers also affect low-flying species like the endangered Quino checkerspot butterfly and the ferruginous pygmy-owl.

To-do list

“We urge the US government to recognize and give high priority to conserving the ecological, economic, political, and cultural value of the US-Mexico borderlands,” the letter explains. “National security can and must be pursued with an approach that preserves our natural heritage.”

Miller says scientists have a responsibility to use their knowledge to help politicians make smart decisions. As for the rest of us, the scientist advises, “We can all call our representatives and senators, or write opinion pieces in our local newspaper to share our voices—it all makes a difference! If Congress doesn’t know we care about biodiversity, just as much as national security, they will trade it away by extending the wall.”