Opposition to Trump administration plans for dozens of miles of new boundary fencing in the biodiverse Lower Rio Grande Valley is intensifying as government-hired contractors begin clearing trees and brush for the project along the U.S. border with Mexico.

Communities and environmental groups are fighting U.S. Department of Homeland Security plans to build about a dozen new stretches of fencing in southeastern Texas using some of the US$1.3 billion Congress granted last year for border security. The barriers will bisect one of the richest areas of biodiversity in the United States, including the prized National Butterfly Center, a 100-acre (40-hectare) nature reserve that straddles the border with Mexico. “You’re talking about decimating the wildlife of the Lower Rio Grande Valley,” says Tiffany Kersten, a board member of Friends of the Wildlife Corridor, a nonprofit citizens’ group that supports wildlife refuges in the Lower Rio Grande Valley.

The new sections, covering some 33 miles (53 kms) in all, would fill gaps between about 54 miles (87 kms) of existing barriers erected in 2008. In Hidalgo County, where the National Butterfly Center is located, the new structure would be built on a levee that runs along the north bank of the Rio Grande.

According to U.S. Customs and Border Protection (CBP), the southern slope of the levee will be replaced by a 15-foot-(4.6-meter-) high sheer concrete wall topped with 18-foot- (5.5-meter-) high steel bollards.

In addition to the 2018 funds, Congress in February agreed to spend $1.375 billion on border security in fiscal 2019, potentially allowing the Trump administration to build a further 55 miles of new fencing in the Rio Grande Valley. These funds were granted on condition that certain environmentally sensitive areas, the butterfly center among them, be spared from the projects. But green activists fear President Trump will use a border-security emergency declaration he issued recently to override such restrictions, and are taking preemptive legal action. The Frontera Audubon Society in February challenged the emergency declaration in U.S. District Court for the District of Columbia, as did—separately—a trio of environmental groups, including the Center for Biological Diversity.

Temperate, desert, coastal and subtropical climates converge in the Lower Rio Grande Valley, which is a funnel for migrating birds and the northernmost point of the range of many Central and South American birds. Some 500 species of birds—over half of all bird species that exist in the United States—have been spotted there, including 30 that cannot be seen anywhere else in the United States, Kersten says. 

The valley also is home to the butterfly center, a Mission, Texas, wildlife preserve and botanical garden that is a project of the nonprofit North American Butterfly Association. Marianna Treviño Wright, the center’s executive director, says the barrier would bisect the preserve, leaving one third of the property north of the fencing and two thirds to the south. She says the barrier would create a flood hazard, hinder the movement of mammals and low-flying butterflies, and obstruct employees and tourists. Says Treviño Wright: “We’re very concerned about the impacts, environmental and economic.”

Wildlife corridor concerns
The barrier also would traverse the National Wildlife Refuge, a series of protected tracts established in 1979 by the United States Fish and Wildlife Service in an effort to create a wildlife corridor along the lower 275 miles (443 kms) of the Rio Grande’s northern banks. The refuge was established in response to land clearing for farms and other development that environmentalists say has consumed all but about 5% of the region’s habitat. Plants such as Walker’s manioc (Manihot walkerae) and star cactus (Astrophytum asterias) are listed as imperiled in the state.

Wildlife currently can move among the non-contiguous riverbank tracts, but their access would be blocked by the new barriers, which Kersten says will “literally undo 100% of what the National Wildlife Refuge set out to do.”

Conservationists have resisted border-barrier plans for years. The North American Butterfly Association sued the government in 2017, after government contractors began clearing brush on butterfly-center land without permits. The suit contended that the work violated the association’s constitutional right to property as well as the National Environmental Policy Act and the Endangered Species Act. It was dismissed last week by the U.S. District Court for the District of Columbia; Treviño Wright says the association is weighing its legal options.

Concern about construction of border fencing in and around the butterfly center heated up on Feb. 3, after contractors and CBP agents crossed the property and parked heavy equipment on land immediately to the east and west of it, says Treviño Wright. She reports that the crews are currently clearing land west of the center, on land that belongs to the National Wildlife Refuge and is called La Parida Banco.  

Fatal in floods
Scott Nicol, co-chair of the Sierra Club’s borderlands campaign, says that steel bollards, despite having space between them, would become a solid wall during floods because they tend to fill with debris. Animals that would flee northward over the levee in the absence of a barrier would be blocked, he says. In the aftermath of flooding in 2010, hundreds of shells of the threatened Texas tortoise (Gopherus berlandieri) were found near existing fencing, indicating the reptiles had been trapped by the barrier as the waters rose.

Because the Rio Grande meanders and the fencing would run fairly straight, sizeable tracts of land would be left isolated between the barrier and the river. The bollard fencing would cut across the northern portion of Bentsen-Rio Grande Valley State Park in Hidalgo County, for example, leaving much of the 760-acre (308-hectare) park south of the barrier. 

CBP also would clear a 150-foot- (46-meter-) wide “enforcement zone” the length of the new barriers, removing vegetation, building access roads and installing floodlights. All told, the project would destroy about 600 acres (243 hectares) of habitat along the 33 miles of new fencing, further degrading a region where development already has taken a crushing toll.

Experts say animals such as the 50 to 80 ocelots (Leopardus pardalis) remaining in the valley—the only wild ocelot population in the United States—would see their range restricted to one side of the barrier or the other. That means they’d have a far harder time finding prey and mates, the experts add. 

Nicol says the political fight over President Trump’s project is divorced from the region’s environmental and social realities. “Most members of Congress don’t know anything about [the area], and they don’t care,” he says. “If ocelots go extinct, that’s not part of their reality. If people’s farms are condemned, that doesn’t matter to them. It’s tremendously frustrating.”