Construction is underway on a stretch of President Trump’s border wall cutting through the Lower Rio Grande Valley National Wildlife Refuge in Texas. Biologists warn the steel wall will disrupt carefully preserved habitat critical for the survival of ocelot, jaguarundi, and other threatened species.

As Tiffany Kersten descends from a levee into a verdant forest that stretches to the Rio Grande more than a mile away, she spots a bird skimming the treetops: a red-tailed hawk. Later, other birds — great blue herons, egrets — take flight from the edge of an oxbow lake. This subtropical woodland is one of the last remnants of tamaulipan brushland — a dense tangle of Texas ebony, mesquite, retama, and prickly pear whose U.S. range is now confined to scattered fragments in the Lower Rio Grande Valley in south Texas. The ecosystem harbors an astonishing array of indigenous wildlife: ocelot, jaguarundi, Texas tortoise, and bobcat, as well as tropical and subtropical birds in a rainbow of colors, the blue bunting and green jay among them.

But the stretch of tamaulipan scrub Kersten is exploring, in the Lower Rio Grande Valley National Wildlife Refuge, won’t be around much longer. About 15 feet from the forest edge, Kersten — a board member of a local conservation group — spots red ribbons tied to tree branches on both sides of the trail. Soon, an excavator will uproot those trees to make way for a 140-foot-wide access road and an 18-foot-high wall atop the levee, all part of the Trump administration’s plan to barricade as much of the Texas/Mexico border as possible. On Valentine’s Day, two days before I visited the border, crews began clearing a path for the road, and soon the U.S. Department of Homeland Security (DHS) will plant a cement foundation in the levee and top it with a steel bollard barrier.

This construction is the first project under a plan to build 33 miles of new wall along the levee in South Texas, with $641 million in funding that Trump requested and Congress authorized last year. That 33-mile stretch, cutting through some of the most unique and endangered habitat in the United States, will be joined by an additional 55 miles of wall under a funding bill Trump signed February 15 that allocates another $1.375 billion for wall construction. The same day, Trump also issued a national emergency declaration authorizing another $6 billion for border walls. That declaration could give the administration the power to override a no-wall zone Congress created in three protected areas around the Lower Rio Grande Valley National Wildlife Refuge.

Since the mid-20th century, ranches, oil fields, and housing tracts have consumed 97 percent of the tamaulipan brushland.

Since the mid-20th century, ranches, farms, oil fields, subdivisions, and shopping centers have consumed 97 percent of the tamaulipan brushland habitat at ground zero of this new spate of border wall construction. That loss led Congress to create the Lower Rio Grande Valley National Wildlife Refuge in the 1970s and spurred a 30-year-effort by the U.S. Fish and Wildlife Service, conservation organizations, and private landowners to protect the remaining pockets of tamaulipan brushland and restore some of what has been lost. The Fish and Wildlife Service has purchased 10,000 acres of cropland and converted it back into tamaulipan woodlands; it hopes to replant another 30,000 acres. The refuge, now totaling 98,000 acres, has been likened to a string of pearls, with connected jewels of old-growth and restored habitat adorning the 300-mile lower Rio Grande Valley. Into this carefully rebuilt wildlife corridor now comes the disruption of a flurry of new border wall construction. Scientists and conservationists across Texas warn that it could unravel decades of work to protect the tamaulipan brushland and the wildlife it harbors. “This is the only place in the world you can find this habitat,” says Kersten, a board member of Friends of the Wildlife Corridor, a non-profit group that works closely with the Fish and Wildlife Service on the corridor program. “And only 3 percent of this habitat is remaining.”

For all its efforts to turn cropland into federally protected habitat, the Fish and Wildlife Service finds itself with little recourse to safeguard it, precisely because it is federal property. The easiest place for the federal government to begin its new wave of border wall construction is the Lower Rio Grande Valley National Wildlife Refuge, which includes the picturesque La Parida Banco tract, where I joined Kersten. Under a 2005 law, the Department of Homeland Security can waive the environmental reviews that federal agencies such as the Fish and Wildlife Service typically conduct for projects that could alter federally protected lands. [Repeated efforts to interview officials from Fish and Wildlife and Homeland Security were unsuccessful.]

Existing border wall, completed in 2009 at the Hidalgo Pumphouse and Birding Center, already cuts off access to a 900-acre section of the Lower Rio Grande Valley National Wildlife Refuge. AP Photo/Eric Gay

The tract Kersten and I visited is one of four adjacent “pearls” in the wildlife corridor — long , roughly rectangular parcels stretching from an entrance road to the river. From west to east they are the Lower Rio Grande Valley National Wildlife Refuge’s La Parida Banco tract, the Bentsen-Rio Grande Valley State Park, the refuge’s El Morillo Banco tract, and the privately owned National Butterfly Center. A levee runs through all four properties, and the first sections of fence to be built atop it would cut off access to trails and habitat in the refuge tracts. Citizens and local and state officials have successfully fought to keep the fence from crossing the National Butterfly Center, the Bentsen-Rio Grande state park, and the Santa Ana National Wildlife Refuge farther downstream — at least for now. If Trump’s national emergency declaration survives court challenges, the border barriers could even be extended into these holdouts. When the wall and access road are completed at La Parida Banco, a crucial piece of intact native habitat will become isolated between the wall and the river. Species that either rely on the river for water or migrate across it will find pathways they’ve traversed for thousands of years blocked. While biologists are concerned about the impacts of the wall all along the U.S.-Mexico border, the uniqueness of South Texas’ ecosystems make it an especially troublesome place to erect an 18-foot fence, they say. The 300-mile wildlife corridor in South Texas, where the temperate and the tropical intermingle, is home to an astounding concentration of flora and fauna: 17 threatened or endangered species, including the jaguarundi and ocelot; more than 530 species of birds; 330 butterfly species, about 40 percent of all those in the U.S.; and 1,200 types of plants. It’s one of the most biodiverse places on the continent.

`There will be no concern for plants, endangered species [and] no consultation with the Fish and Wildlife Service,’ says a biologist.

“This is a dry land, and when you have dry land, your diversity is near the water,” says Norma Fowler, a biologist with the University of Texas at Austin who studies the tamaulipan brushland ecosystem. She co-authored an article published last year in the scientific journal Frontiers in Ecology and the Environment warning of the consequences of the new wall for the region’s singular ecosystems and wildlife. Since the wall can’t be built in the river, it’s going up a mile or more north of it in some areas, placing both the riparian habitat right along the river and the tamaulipan thornscrub on higher ground at risk. “Both of those habitats have been fragmented, and there’s not much left,” Fowler says. “Some of it is lovingly restored from fields to the appropriate wild vegetation. But because they’ve waived every environmental law there is, there will be no concern for plants, endangered species. There will be no consultation with the Fish and Wildlife Service.”

When the wall rises, the barrier and the new patrol road alongside it will cut an unusually wide 140-foot swath to improve visibility through the dense brush. In her article, Fowler estimated that construction of the border wall would destroy 4.8 to 7.3 acres of habitat per mile of barrier. The fence will also cut off access to the river and habitat on the Mexican side of the border for many animals. Including bobcats, ocelot, jaguarundi, and javelina. Some slower-moving species, like the Texas tortoise, could be caught in floods that would swell against the wall.

The subtropical woodland that lines the Rio Grande in Texas provides critical habitat for various species, including javelina [left] and endangered ocelots. USFWS

If new walls must be built along the Rio Grande, Fowler says, the Department of Homeland Security should construct them in a way that causes the least harm to wildlife and plants. That would include limiting the footprint of the access roads and other infrastructure, designing barriers with gaps wide enough for animals to pass through, and using electronic sensors instead of physical barriers wherever possible. One of the most at-risk species is the ocelot, a small jaguar-like cat that historically roamed throughout Texas, Arkansas, Louisiana, and Arizona, but that numbers only about 80 today. The sole breeding population left in the U.S. is in South Texas, and it is wholly dependent on the dense shrubland in the Lower Rio Grande Valley that the wall will bisect. Some species could be wiped out altogether: The few sites where Physaria thamnophila, a native wildflower, still grows are directly in the path of the wall, Fowler says. With 1,254 miles of border — all following the languid, meandering course of the Rio Grande — Texas has far more of the United States’ 1,933-mile southern boundary than any other state, yet it has the fewest miles of existing fence. That’s because much of the Texas border is private riverfront land. The first major push to barricade the Texas border, by the George W. Bush administration, encountered opposition from landowners who balked at what they saw as lowball purchase offers and the use of eminent domain to take their property. (Years later, some of those lawsuits are still pending.) Federal land managers also put up a fight.

Natural areas already bisected by a Bush-era fence offer a preview of the potential fate of the Rio Grande wildlife refuge.

When Ken Merritt — who oversaw the federal South Texas Refuge Complex, which includes the Lower Rio Grande Valley National Wildlife Refuge, Santa Ana, and the Laguna Atascosa refuge near where the Rio Grande meets the Gulf of Mexico — questioned the wisdom of a barrier through Santa Ana during the Bush administration, he was forced out of his job. “I was getting a lot of pressure,” says Merritt, who still lives in the valley and is retired. “But it just didn’t fit. We were trying to connect lands to create a whole corridor all along the valley, and we knew walls were very much against that.” Natural areas already bisected by the Bush-era fence offer a preview of the potential fate of the Lower Rio Grande Valley National Wildlife Refuge. A few miles downstream from the La Parida tract, the Hidalgo Pumphouse and Birding Center, which anchors the southern end of the tiny town of Hidalgo, now looks out at a stretch of steel bollard fence atop a concrete wall embedded in the levee. On a recent Monday morning, a few tourists milled about the gardens behind the pumphouse, listening to the birds — curve-billed thrashers, green monk parakeets, kiskadee flycatchers — and enjoying the view from the observation deck. Curious about the wall, all of them eventually walk up to it and peek through the four-inch gaps between the steel slats. On the other side lies another pearl: a 900-acre riverside piece of the Lower Rio Grande Valley National Wildlife Refuge called the Hidalgo Bend tract. It was once a popular spot with birders drawn to its ferruginous Pygmy owls, elf owls, and other wildlife. But since the wall went up in 2009, few birders visit anymore.



Activists march near the Lower Rio Grande Valley National Wildlife Refuge on February 16, protesting the construction of new border wall segments. April Reese

At The Nature Conservancy’s Sabal Palm Preserve, a 557-acre piece of the wildlife corridor near the Gulf of Mexico, a wall installed in 2009 cuts through one of the last stands of sabal palm forest in the Rio Grande Valley. Laura Huffman, regional director for The Nature Conservancy, worries that the more walls erected on the border, the less hope there is of completing the wildlife corridor.

Kersten and others remain unconvinced that the danger on the border justifies a wall. She believes that sensors and patrols are a better alternative, but that there are more than enough of those already. Earlier on the day we met, Kersten was part of a group of 100 or so protestors who marched from the parking lot at nearby Bentsen-Rio Grande Valley State Park to the adjacent National Butterfly Center, holding signs that read “No Border Wall” and “Solidarity Across Borders.” One placard listed the more than two dozen environmental and cultural laws that the Trump administration waived to expedite the fence. Among them: the National Environmental Policy Act, which requires environmental analysis before federal projects can begin; the Endangered Species Act; the Clean Water Act; the Migratory Bird Treaty Act; the National Wildlife Refuge System Administration Act; the National Historic Preservation Act; and the Native American Graves and Repatriation Act. Even as the wall goes up in the refuge, preparations for this year’s restoration projects are moving ahead. Betty Perez, whose family has lived in the Lower Rio Grande Valley for generations, is one of several landowners who grow seedlings for replanting on refuge lands each year. At her ranch, about a 45-minute drive northwest of the La Parida Banco tract, she’s beginning to collect seeds to grow this year’s native shrub crop: coyotillo, in the buckthorn family; yucca; Texas persimmon.