During Donald Trump's first term as president, he embarked on an ambitious and costly plan to militarize the border, including building more than 450 miles of wall, cutting off wildlife corridors and encroaching on some of the country's most Destroying ecosystems in remote and most biodiverse areas. With his second inauguration on Monday, environmentalists are bracing for any new construction phases that could exacerbate the ecological toll of the border wall.

"It's absolutely a disaster for border wildlife," Margaret Wild, a human environmental geographer and political ecologist at the University of Arizona, said of the environmental impact of the existing border wall and the prospect of rebuilding it. "It's a travesty and a disaster." She said the wall undermines "decades of binational cooperation between the United States and Mexico to protect this fragile and biologically diverse region." I don’t think Americans realize what’s at stake. "

The problem is that the construction of more than 635 miles of pedestrian border wall along the southern border has segregated wildlife populations to an unprecedented degree in history—making any larger animals except jackrabbits essentially impassable. “This (border wall) is a massive, uncontrolled experiment in the evolutionary history of wildlife species along the border,” said Laken Jordahl, Southwest Conservation Advocate at the Center for Biological Diversity. "The places that remain unfenced are some of the most remote, rugged and important wildlife habitat we have left."

New Mexico and Arizona have approximately 391 miles of pedestrian border wall, 263 miles of which were built during Trump's first administration.

A recent study by the Wildlands Network and the Sky Island Alliance shows that in the extremely biodiverse Sky Island region of Sonora, Mexico, and the southwestern United States, pedestrian border walls (30-foot-tall steel posts spaced 4 inches apart) are harmful to wildlife. Effects of animal movements and habitat connectivity. Motion-activated cameras placed along 100 miles of the Arizona border showed an 86% reduction in wildlife crossings, and a 100% reduction in large animals such as bears, pronghorns and jaguars.

"Sky Island is a crossroads of continents, and many different species, including humans, have passed through it over thousands of years," said Emily Burns, project director of the Sky Island Alliance. “Constructing a continuous wall on the Arizona border would be extremely detrimental to medium- and large-sized wildlife.”

All signs point to Trump continuing to take a hard line on immigration and the southern border. Trump has criticized the Biden administration's auction of border wall materials, calling the sales "almost criminal" and will cost taxpayers millions of dollars when Trump resumes border wall construction. "They know we're going to use it, and if we don't have it, we're going to have to rebuild it and it's going to cost twice as much as it did a few years ago," Trump said.

However, specific plans for the border wall remain unclear.

"Nobody knew exactly what was going to happen," Jordahl said. "We will definitely be prepared for the worst-case scenario."

Border wall a signature priority Congress gave the Department of Homeland Security sweeping powers that made Trump's candidacy possible for the first time. The powers allow for bypassing federal law to speed up construction and bolster border security through Customs and Border Protection, the nation's largest law enforcement agency.

Ricky Garza, border policy adviser for the Southern Border Communities Alliance, has witnessed the steady spread of militarization along the Rio Grande Valley border.

“The entire area is blocked off by Border Patrol,” Garza said, referring to the growing number of green and white Border Patrol vehicles, immigration checkpoints and border infrastructure. “This material occupational structure increases as you get closer to the border.”

Texas has the longest border with Mexico but the least mileage of fence because the border is formed by the Rio Grande and the land on the Texas side is mostly privately owned. Border wall construction is more common on federally owned lands, not because these are busy immigration crossings, but because it is extremely difficult to build a border wall on private property. During the Trump administration, 263 miles of pedestrian fencing and border wall were built in much of rural New Mexico and Arizona. Today, more than 60% of Arizona's border areas are fenced.

"In those very remote, rugged areas, whether it's the mountains of Arizona or elsewhere, there's no indication of anyone trying to cross the border, at least in terms of numbers," said former Customs and Border Commissioner Jill Krikowsk. Gil Kerlikowske said. Protect. "So why try to build any kind of border wall where it's not really needed?"

When I visited the Arizona border in the final days of Trump’s first term, construction crews were busy blasting away hilltops and leveling hillsides to complete disconnected sections of the border wall in some of the most remote and impassable areas of the border.

Burns, of the Sky Island Alliance Project, worries that construction could resume in those areas because federal laws to build the wall remain exempt. "There are construction plans where the wall has been lifted," Burns said. "It seems likely that old projects will be dusted off and restarted."

Kerlikowske isn't so sure. "Tom (Homan) has made it clear that he wants to focus more or less on the border," he said of Trump's incoming "border czar."

“What’s truly troubling is that the unsegregated portion of the border between Arizona and New Mexico is the most sensitive place and important wildlife corridor for species like black bears, jaguars and other mammals,” Myles of Borderlands Myles Traphagen, Wildlands Network Program Coordinator.

The closure of the unfenced zone would be a death knell for the elusive jaguar, which has reappeared in the United States after being hunted to extinction in the 1960s.

"More (walls) would certainly cut off jaguars' access to the United States in their final corridor from Sonora to Arizona," Burns said. "When these animals move, it's a lifeline for endangered populations. ”

Border construction is a bipartisan effort. The Obama administration built more than 100 miles of new border wall. Biden resumed construction in 2023 after a failed attempt in 2019 to reallocate funds for the border wall. "This money is appropriated for the border wall," Biden said. "I can't stop it."

A CBP spokesperson said that starting in 2021, the agency has prioritized barrier funding to close gaps and complete gates at the southern border. Of the 163 gap-filling and gate projects approved since 2021, 119 have been completed.

About 57 miles of new border barrier gaps are planned to be closed. The projects are still in the environmental planning process and are expected to begin in early 2025, according to CBP.

Border barriers are deadly to both wildlife and humans. The border wall and U.S. Customs and Border Protection's decade-long policy of deterrence have pushed people into more dangerous and hostile situations.

"The border wall is an engine of death," said Garza of the Southern Border Communities Alliance, because the southern border is now the deadliest land migration route in the world.

With Trump back in office, he fears things will only get worse. “I don’t want my home to become a sacrifice zone, but that’s what we’re working towards.”