Where the border wall ends, wildlife survives. Advocates fear losses if the gaps close

MONTEZUMA PASS — From atop the south end of Arizona’s Huachuca Mountains, the borderland paths of America’s solitary jaguars and ocelots sprawl across Sonoran Desert scrublands

To the south: Mexican wildlands shelter breeding cats that periodically send bachelor scouts into their once-and-maybe-future strongholds in the United States. To the east: a border wall stretching for 70 miles from the foothills almost to New Mexico blocks the path of these rarest of American mammals, especially at what might otherwise be prime cat-cloaking tree cover along the shallow San Pedro River.

But to the west, a back door of sorts:  Arizona’s remote San Rafael Valley rolls out, fortified by a chest-high fence of horizontal steel rail barriers that block vehicles but not four-legged wanderers. President Donald Trump and previous presidential administrations have yet to wall off the rippling wilds spreading toward the Patagonia Range.

Beyond there, the wall picks up again at Nogales but gives out in the rugged Pajaritos and then again at the Baboquivaris, where a mountain sacred to the region’s O’odham people has welcomed multiple meandering jaguars in recent decades.

An ocelot that has triggered trail cams for several years in the southern Huachucas likely trotted north from oak to oak through the San Rafael to reach this place from a small breeding population some 30 miles to the south.

“This is Ground Zero right here,” Myles Traphagen said, gazing westward across the wild southern end of the San Rafael Valley, the place where that spotted little big cat must have crossed into Arizona. “This is one of the places where I’d proverbially fall on my sword.”

The valley — and the Huachuca and Patagonia ranges that bound it — are that back door, still cracked open for a potential rebirth of American jaguar and ocelot breeding populations.

It might well come to “proverbial swords” for Traphagen and others who want to keep this door propped open so that the cats and other rare creatures can go where they must in a warming and drying era. In April, U.S. Customs and Border Protection confirmed that it would soon offer new contracts for border wall construction, including one segment that would stretch 25 miles from mountain to mountain and seal off the San Rafael.

Some wildlife advocates who monitor border developments said it was the news they had feared since Trump returned to office, and that they would seek to shape the construction specifications to ensure it includes hinged doors big enough for large animals, such as those installed and often kept open and under surveillance where waterways cross the border.

“This valley represents Southern Arizona’s last unwalled major biodiversity hotspot in the border region, a critical wildlife corridor in the middle of the Sky islands and in the birthplace of the Santa Cruz River, where species like the endangered jaguar and ocelot, as well as black bear and other species roam,” Sierra Club borderlands coordinator Erick Meza said in a written statement responding to the news. “Blocking 25 miles of this landscape will sever connectivity for countless animals, pushing already vulnerable species closer to extinction.”

Arizona’s Sky Island mountain ranges historically were a northern frontier for the cat species before local extirpation in 20th century. Starting in the 1990s they crept back, one male at a time, sometimes fleetingly but sometimes wandering alone for years and occasionally tripping motion-activated cameras. One jaguar has been detected dozens of times since 2019 as he roamed the Chiricahua Mountains. Federal biologists have designated much of the southern Arizona mountains as critical jaguar habitat, a suitable homeland waiting for a female to join a mate north of the border.

The ranges are also a critical gateway for black bears that struggle to persist south of the border and for countless smaller creatures that don’t recognize international borders.

Between 2017 and 2021, the first Trump administration built 263 miles of new steel wall along the southern edge of Arizona and New Mexico, according to Traphagen’s survey for his employer, the Wildlands Network. In Arizona, it sealed off the south ends of Organ Pipe Cactus National Monument and Buenos Aires National Wildlife Refuge, the San Bernardino Valley east of Douglas, and desert and mountain zones in between.

Blasting through rock near the Arizona-New Mexico line, builders nearly walled off the Peloncillo Range, another passage through which individual jaguars have rambled north into the states. Camera traps a few miles to the south have recently confirmed several jaguars, including relatively small cats, a finding that Traphagen views as tantalizing because where cubs occur, a female must be nearby.

Now, he and other defenders of the Southwest’s wildlands are girding for a new battle with a second Trump administration they expect will pursue another wall-building blitz. This time, they fear, the border builders may conquer the remote zones that eluded them the first time — the very zones most conducive to movement of secretive cats. And they acknowledge that with Congress having exempted the border from the nation’s environmental laws, there may be little they can do besides lobby Congress to reverse course before it’s too late.

“Once you start blasting through a mountain,” Traphagen said, “there’s no going back.”

The wall stops cats, but also rare fish

Homeland Security Secretary Kristi Noem traveled to Nogales in March to film a video announcing the restart of wall construction elsewhere along the U.S.-Mexico border. Doing so does not require the environmental reviews or endangered species protections typical of major federal projects because Congress granted presidential administrations the power to waive laws at the border in response to the Sept. 11, 2001, terrorist attacks.

“Everybody, I’m here in Arizona, and right at this spot you can see where the border wall ends,” Noem said in a video shared to X. “As of today, we’re starting 7 new miles of construction. We’re going to continue to make America safe again.”

On April 11, Trump signed a national security memorandum authorizing the U.S. military to operate throughout federal lands in what’s known as the Roosevelt Reservation, a narrow band under various agency jurisdictions along the border. This gives the military a larger role in aiding Border Patrol agents to turn back border crossers.

“Our southern border is under attack from a variety of threats,” the president said in his memo. “The complexity of the current situation requires that our military take a more direct role in securing our southern border than in the recent past.”

Conservationists question whether marching either troops or the wall through the remotest stretches of desert and mountain will accomplish that goal when most migrants and drugs come through or near populated border checkpoints. They argue that Border Patrol agents with camera towers, night vision and eyes in the sky more effectively thwart the relatively few border crossers who march across remote valleys and mountains.

Without building any new wall, the administration’s border tactics have slowed the flow of migrants across the Southwestern border, where Border Patrol agents have reported fewer than 10,000 arrests a month this year, including 7,180 in March. That’s down from a monthly average of 155,000 over the last four years.

“Militarizing wild lands under the guise of national security will sacrifice ecosystems and wildlife to a manufactured emergency, turning public lands into designated war zones instead of preserving them for future generations,” Russ McSpadden of the Center for Biological Diversity said in a statement responding to the president’s memo. “Trump’s order is part of a series of reckless actions that will do immense damage to some of the most beautiful wild places in the borderlands.”

It’s not just the rare mammals that conservationists fear a wall will harm. Several highly endangered fish live flush against the border, already imperiled by a warming climate with less reliable summer monsoon rains.

In February, the Center for Biological Diversity accompanied The Arizona Republic to California Gulch, a saguaro-studded arroyo across the Pajarito Mountains from Nogales. There, in the waning days of the Biden administration, the government had completed a short gap in the border wall that Homeland Security officials considered a tempting portal for migrants. In building up a base and roadbed atop which they could construct a gated wall, they had sliced across a dry waterway that allows rare Sonora chubs to slosh back and forth from tiny oasis to oasis when summer rains flood the streambed.

Just upstream on the U.S. side, center scientist Krista Kemppinen squinted to see deep into a hot tub-size pool harboring tiny fish in a pocket of rock. While a swarm of fish swam there, waiting for the next chance to break out and find new digs during a flood, she was unsure if she was seeing any of the endangered Sonora chubs. Some of the fish looked like non-native green sunfish. A couple could have been bass.

“The fact that there’s more than one fish is not good,” Kemppinen said, “because (Sonora chubs) are the only ones that are native here.”

Pile the invading predators and competitors atop drought and, now, a wall blockading future reinforcements from Mexico, and Kemppinen fears you have a recipe for U.S. extinction of the species.

“The fish have always come from Mexico to help out this population in the past,” she said.

On the border: Arizona’s Sky Islands are a ‘treasure’ that warming climate and mining threaten to bury

If they turn on the lights, a rare fish may not survive

Northwest along the border, at Organ Pipe, another exceedingly rare fish — the Quitobaquito pupfish — swims in the shadow of the border wall. Construction there, in 2020, sped a dry-up that might have eliminated the fish if not for a rescue staged by the National Park Service and partners who temporarily removed them and Sonoita mud turtles from a rapidly disappearing spring-fed pond so they could line the water body and return them to relative safety.

Quitobaquito Springs had been drying up for 20 years, another victim of a warming and desiccating climate, said McSpadden, the center’s Southwest conservation advocate. Then came the crew pumping groundwater to mix the concrete to fill a 6-foot trench as a footer for the wall’s steel pillars. Between that and dust suppression, they used 84,000 gallons a day for 45 days — millions of gallons.

The hills surrounding Quitobaquito showed the after-effects of a poor 2024 monsoon, followed by a typically dry winter. The bunched columns of the organ pipe cactuses stood scrawny and yellowed from thirst.

“They’re looking rough,” McSpadden said. “And the drier we get, the more significant places like Quitobaquito become.”

The spring is the only reliable water for 100 miles, he said, and conservation partners on the Mexican side report finding the carcasses of javelinas that may have died trying to reach the watering hole. Where seven springs once fed tiny rivulets to the pond, now only two are apparent.

Although the wall is already built, there’s yet another action that McSpadden fears the Trump administration could take to further imperil the pupfish. The president’s previous administration erected some 1,800 high-powered light towers along the Arizona-Sonora border, the longest stretch of which includes 740 towers across roughly 25 miles on Organ Pipe’s edge. That includes Quitobaquito.

But while the lights were partially wired, they were never connected and illuminated, and Customs and Border Protection under the Biden administration had pledged not to do so. Environmentalists argue that reversing course would be counterproductive for apprehending border crossers, too, because it would negate the advantage that U.S. agents have with night vision goggles.

If the new administration were to change course and spotlight the border, it could further disrupt the ecosystem.

Bats pollinate saguaros in darkness. Fish swim toward light, which is how biologists sometimes capture them at night in light traps. Bright lights shining all night every night could alter this place and its species profoundly.

“Quitobaquito Spring evolved over thousands of years with nighttime being dark time,” McSpadden said. “It’s going to change the function of the system.”

‘This is our home … I want the wall down’

These waters are more than natural history to Lorraine Eiler. They’re key to her cultural heritage. Eiler, 88, lives north of Organ Pipe in Ajo, but her Hia-Cet O’odham ancestors lived around Quitobaquito Spring before the National Park Service claimed the land.

“It had everything in order for our people to survive,” she said, “you know, with the water here. And they had their gardens and their orchards and all the animals that came around. And it was a very flourishing, flourishing place because there was a lot of greenery here.”

Eiler visits the spring frequently, and she worries about the wall’s effects. It blocks the natural flow of stormwater across the border, she said, and could cause the pond to silt in. She participated in the Park Service’s rescue of fish and turtles, something that she wishes hadn’t been necessary.

On a February day in the spring, she found plenty that might feed a traditional O’odham family, including wolfberry and mesquite beans, signs that the place can still be a natural garden despite continuing drought.

Eiler grew up as a non-entity in her land, a remnant of a tribe whose name means “sand dune people” but who were few and never won formal recognition from U.S. officials.

“We were classified as being extinct,” she said. But they persisted in the Sonoran Desert, and eventually, the affiliated Tohono O’odham Tribe, with its large reservation in the area, incorporated them. “In 1984, I became a legal Indian,” she said.

Although she can’t live at Quitobaquito like her great-grandparents did, she can still honor them and continue their legacy by helping to conserve this place.

“This is our home and we want people to respect it,” Eiler said. “I want the wall down.”

Sky Islands: ‘Rarer creatures’: Elegant trogons, hummingbirds alter flight paths as drought persists

Will the wall slow migrants or offer false sense of security?

Republican senators in January introduced a bill called the Wall Act to dedicate $25 billion to completing the border wall, which could lead to filling in gaps such as dozens of miles across the San Rafael Valley and, nearer Organ Pipe, the Tohono O’odham Reservation, where tribal members have always had free access to traditional lands on both sides of the border.

“President Donald Trump and the Republican majorities in the House and Senate have not just a mandate but an obligation to secure the border and protect American families,” Alabama Senator Katie Britt said when introducing the bill in January. “The United States needs a completed border wall — it is just common sense to have a physical barrier in place to ensure only lawful entry into our country.”

Noem’s visit to the border wall at Nogales heralded the second Trump administration’s first new wall construction contract, though that $70 million project was actually in Texas. Her department at that time said it intends to “close critical openings” that had remained after President Joe Biden curtailed funding for most new wall segments.

“Completing the border wall in these locations will support the Department of Homeland Security’s (DHS) ability to impede and deny illegal border crossings and the drug- and human-smuggling activities of cartels,” Customs and Border Protection said in a news release.

Borderlands environmentalists believe they have that backward — that the wall is easily breached and gives merely a false sense of security. It’s the border agents and their superior technology, and not the wall, that stop unauthorized crossings, they say.

Trail-cam images: A bobcat can pass through the border wall, but most larger species can’t, study finds

They believe the construction makes movement through the borderlands easier and faster. The road that now parallels the border wall at Buenos Aires National Wildlife Refuge is a smooth gravel throughway, with concrete pavement where it dips into arroyos to prevent excessive erosion.

“This is like a superhighway and I never see anyone out here,” McSpadden said while driving east from Sasabe toward California Gulch. “Someone could hand me something (between the border wall slats) and I could drive off at 55 miles per hour.”

In the past, he said, access required “serious four-wheel-drive.”

Further construction west of Nogales, where Noem stood for her video, could simultaneously increase access for traffickers while fragmenting wildlife habitat. The Pajarita Wilderness spans the hills in that area, and is a “hotbed” of biodiversity for everything from butterflies to occasional jaguars, McSpadden said.

“We’ve always been most worried about the most inaccessible, hardest places, like Pajarita.”

For conservationists, physical wall is ‘a pointless barrier’

Driving in the desert parallel to the border east of Douglas, Traphagen noted a tow strap — the kind of long belt used to tow vehicles — looped over one of the border wall posts and dangling toward the ground. Border crossers use ladders to scale the wall on the south side and then lower themselves by clinging to the strap on the north, he said.

“More people have crossed after the border wall was built than before,” Traphagen said.

As the wall ascends toward the Peloncillos near the New Mexico line, a rock gash in Guadalupe Canyon marks where the first Trump administration blasted through a hillside but then stopped at the end of the term without having completely walled off that mountain range. While this stretch of wall’s price tag averaged more than $120 million a mile, Traphagen said, the cost for the final few miles, with deep blasting, ballooned to $480 million.

To the south, more mountains extend toward the core of the northern jaguar population. Mexico’s Highway 2 runs along the border, after which no barriers would block the cats’ free movement. “It’s a straight, well-watered, well-covered corridor from here to the Northern Jaguar Preserve 120 miles to the south with no highway to impact its passage.”

Continuing the wall east of Guadalupe would block that route without, in Traphagen’s view, any real gains against migration or smuggling.

“We’re blowing these up for what purpose?” he said. “It’s not something that’s solving a human problem.”

Such an extension into New Mexico would visit a second round of destruction on Valerie Gordon, an American conservationist who directs the Mexican conservation reserve Cuenca los Ojos on the Mexican side. The reserve borders on both Arizona and New Mexico for 22 miles, starting on the west end opposite Arizona’s San Bernardino National Wildlife Refuge.

There, during Trump’s first term, the government built a wall and a parallel road across wetlands that Cuenca had spent years restoring from overgrazing and erosion. The nonprofit built small, porous rock dams to slow water so that it could infiltrate the soil, resulting in a tangle of trees and roots that Gordon described as “a green wall.”

Essential environmental news: Sign up for AZ Climate, the latest from The Arizona Republic every Tuesday

The steel wall across that refuge’s south end obliterated much of the restoration. Extending it into New Mexico would destroy more, she said, including the ability of black bears and jaguars to continue traversing the property to get north or south.

She noted that the U.S. Fish and Wildlife Service in the past has helped fund some of Cuenca’s work on the Mexican side because it extends habitat for species native to or migrating through both countries. It’s wild country with great potential for international collaboration on conserving or even rewilding rare species, Gordon said.

The U.S. refuge has struggled to conserve rare fish such as the Yaqui catfish, though it swims in Cuenca waters. Some 400 species of bees live on the reserve but are repelled by the wall, she said.

“What a perfect place for an international wildlife refuge, an international corridor, and yet,” she said, “and yet there’s serious destruction and there was really no consideration of anything south of the border. That seems tragic. It also seems incredibly small-minded.”

Like other borderland conservationists, Gordon believes high-tech surveillance of border-crossers would be more effective — and cost-effective — than extending the wall.

“It’s a physical barrier,” she said. “It’s an emotional barrier. It’s a pointless barrier.”

At Quitobaquito Springs in Organ Pipe Cactus National Monument, Ruth Edelman was among the tourists seeking the splendor of an oasis in the Sonoran Desert in February. For Edelman, of Avalon, N.J., it was a repeat of a trip she had made to the site more than a decade ago. This time, with the wall, the built-up road and the new lining under the pond, she was disappointed.

“I don’t recognize it,” she said, “I guess because to me it was so pristine before. Now it looks like it’s been manipulated by man.”

From listening to ranger-led talks, she knew Quitobaquito was considered sacred and an important watering hole for wildlife. It was unfortunate to see it diminished.

“It’s still a beautiful place to visit,” she said. “It’s just sad that things are what they are.”

Brandon Loomis covers environmental and climate issues for The Arizona Republic and azcentral.com. Reach him at brandon.loomis@arizonarepublic.com.

Environmental coverage on azcentral.com and in The Arizona Republic is supported by a grant from the Nina Mason Pulliam Charitable Trust.

Sign up for AZ Climate, our weekly environment newsletter, and follow The Republic environmental reporting team at environment.azcentral.com and @azcenvironment on Facebook and Instagram.

This article originally appeared on Arizona Republic: Gaps in Trump’s border wall leave openings for wildlife survival