Six Endangered Species the Border Wall Might Doom

The habitat of the Sonoran pronghorn in the deserts of Arizona and Sonora is already fragmented by roads, canals and ranchers’ barbed wire fences. (Photo by Greg Joder/ Arizona Department of Game and Fish)

LOS ANGELES – President Donald’s Trump’s promise to build a wall along the U.S.-Mexico border would be a disaster for wildlife. The existing barriers have already taken a heavy toll on borderlands plants and animals, as has the Department of Homeland Security’s border enforcement activities’ legal exemption from most environmental laws.

A continuous wall along the nearly 2,000-mile border would cut through the habitats of 62 critically endangered, endangered or vulnerable species, according to an analysis published in BioScience. The construction and maintenance of the proposed wall poses immediate threats to 96 different species, ranging from endangered cacti and desert pupfish to California condors and golden eagles, according to a report by the Center for Biological Diversity.

We feature six of those species here. All are listed as endangered under the U.S. Endangered Species Act.

Sonoran Pronghorn

The pronghorn, Antilocapra americana, is the fastest land mammal in North America. They can hit almost 60 miles per hour in a sprint. Biologists suspect the beasts, also known as “antelopes” though they’re not closely related to true antelopes, inherited their speed from ancestors who spent a lot of time outrunning the now-extinct American cheetah.

A Sonoran pronghorn is released into the Barry Goldwater Air Force Range in Arizona. (Photo courtesy USAF)

Sonoran pronghorn, Antilocapra americana sonorae, are just as fast as their cousins elsewhere in North America, but speed doesn’t do them much good against the threats they now face. Their habitat in the deserts of Arizona and Sonora has been fragmented by roads, canals, and ranchers’ barbed wire fences. Much of their range in the U.S. is on an Air Force bombing range, and stress from overflights and explosions takes its toll.

But the biggest problem for the Sonoran pronghorn is the existing barriers along the border, already quite formidable obstacles for animals that despite their speed are not great jumpers. Pronghorn populations in the U.S. and Mexico are already restricted from crossing much of the border, cutting off both migration routes and that all-important flow of pronghorn genes.

That’s a serious problem for an animal that can wake up in one place, then be 75 miles away before lunch. Pronghorn need big ranges to thrive.

The federally endangered Otay Mesa mint, on right, shown with the also-endangered California orcutt grass. (Photo courtesy USFWS)

Otay Mesa Mint

Vernal pools are one of the San Diego area’s most-endangered habitats. Seasonal wetlands with bad drainage where winter rains pool, they provide unique habitats for a variety of plants and animals found nowhere else. And when development or climate change threaten to destroy vernal pools, they can destroy vernal pool organisms as well.

Otay Mesa mint, Pogogyne nudiuscula, a foot-tall, aromatic member of the mint family that sports bright purple flowers, used to be significantly more common, with recorded populations in vernal pools up and down the coast from San Onofre into Baja. It’s now known from just seven spots right along the border in the vicinity of Otay Mesa and the Tijuana International Airport.

Development pressure in the area is bad enough, and local conservationists have had their hands full protecting vernal pool plants like the Otay Mesa mint, as well as neighbors like the also-endangered California orcutt grass.

Development with federal exemption from environmental laws, as would be the case with a fortified border wall, could well be more than Otay Mesa mint can handle.

Habitat loss has pushed the Gulf Coast jaguarundis to the brink of extinction. (Photo courtesy USFWS)

Gulf Coast Jaguarundi

This bobcat-sized feline, Puma yagouaroundi cacomitli, has been on the federal Endangered Species list since 1976. Things haven’t gotten much better for the jaguarundi since then.

Despite the common name, the jaguarundi is much more closely related to mountain lions than it is to jaguars. Mountain lions average about 10 times the size of jaguarundis, leading scientists to conjecture that an isolated population of cougars may have been forced to subsist on small prey such as rodents and frogs for long enough to evolve a much smaller size. Now, the jaguarundi species stretches from southern Argentina through the Amazon, the northern Andes, and Central America to Mexico, with a minute sliver of south Texas at the very northernmost end of the species’ territory.

Jaguarundis as a species seem to be doing okay. But habitat loss has pushed two of the cats’ four subspecies — the Gulf Coast and Sinaloan jaguarundis — to the brink of extinction. When the George W. Bush administration fortified border barriers in the Rio Grande Valley in the mid-2000s, biologists warned that the barrier to migration could doom Gulf Coast jaguarundis on both sides of the Rio Grande.

Populations of the Quino checkerspot butterfly on the other side of the border are doing better, and may provide a bit of insurance against extinction. (Photo courtesy USFWS)

Quino Checkerspot

There used to be a lot more Quino checkerspot butterflies than there are now. When European settlers first came to California, the brightly patterned males could be seen jousting for territory on hilltops from Ventura to Baja California, stretching inland to the fringes of the desert.

Now, there are just three places where Quino checkerspots can be found in the U.S.. One is in the vicinity of Temecula in southwestern Riverside County, where suburban and wine-industry development hasn’t quite erased the last of the butterfly’s habitat just yet. The other two are on the border in San Diego County, one in the Otay Mesa area and the other almost to the Imperial Valley, in Jacumba. Populations on the other side of the border are doing better, and may provide a bit of insurance against extinction; if the States’ Quinos are wiped out, the butterflies may well resettle California from south of the border — kind of a butterfly Reconquista.

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Two big reasons for the loss of historic Quino checkerspot habitat are the Southland’s metastasizing development, and the related effort to control wildfires across the landscape. Some of the most important food plants for larval Quino checkerspots thrive in the wake of fires, and tend to get crowded out when other plants eventually move back into a burned area. That’s especially true with the advent of invasive exotic plants that can outcompete the checkerspot’s native food plants such as plantains and snapdragons.

With 75 percent of its historic U.S. habitat wiped out, a figure that rises to more than 90 along the coast, the Quino checkerspot can’t afford to lose any more habitat. And even if border wall construction activities don’t take out the Quino’s habitat along the border, the wall itself may prove a serious blow to the butterfly.

That’s because despite their wings, Quino checkerspots aren’t strong fliers. They don’t take off at all on cloudy days, and they tend to stick to within six feet of the ground. A 30-foot border wall, despite having little to no effect on crossings by earthbound human beings, may prevent that butterfly Reconquista from taking place, meaning that when California Quinos die out they’ll be gone for good.

There are at least 100 wild wolves living in New Mexico and Arizona as a result of a breeding program. (Photo courtesy USFWS)

Mexican Gray Wolves

Less than a century ago, Mexican wolves, Canis lupus baileyi, ranged into California. By the 1940s, they were extinct in the U.S. due to predator control programs intended to subsidize the ranching industry, and ranchers methodically shot any wolves trying to migrate into the U.S. from Mexico. Mexican wolves in Mexico were swiftly approaching extinction as well due to ranchers’ use of predators poisons. In the late 1970s, wildlife agencies decided to attempt to save the Mexican wolf, and captured a few remaining wild wolves in the states of Durango and Chihuahua as captive breeding stock.

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The breeding program has been a qualified success, with hundreds of Mexican wolves now in captivity. Reintroducing wolves to their former habitat has been a little less successful. There are at least 100 wild wolves living in New Mexico and Arizona as a result of the breeding program, and a handful in northern Mexico after a release there in 2014. The highest death toll of Mexican wolves since the breeding program began happened in 2016, with 14 wolves killed that year. The wolves have fervent enemies, and wolf-hating humans with guns remain the subspecies’ biggest enemy.

If the Mexican wolf is to survive long-term, it will need connectivity between its range in the U.S. southwest and the wilder mountain ranges in northern Mexico.

The Arizona jaguar known as “El Jefe” caught on camera in the Santa Rita Mountains. (Photo courtesy USFWS)


The third-largest cat in the world, and the only North American feline that roars, jaguars only became functionally extinct in the United States in 1963, when the last female jaguar in the U.S. was shot in Arizona’s White Mountains. But the big cats have been trying to repopulate the United States since the mid-1990s, with at least a sighting every few years. Documented sightings have increased recently, though whether that’s due to more jaguars or the explosion of cheap trail cameras is hard to say.

Either way, jaguars seem intent on reintroducing themselves to the U.S., and the chain of forested parks and national forests across the Southwest offers potentially suitable habitat. Though those habitats are largely already inhabited by mountain lions, that doesn’t necessarily mean there’ll be too much competition for resources. Jaguars and pumas do coexist in the jaguar’s present range, mainly because jaguars can take down bigger prey, in the 50-pounds-and-up range. “El Jefe,” Arizona’s lone male jaguar, has even been documented as eating black bears, generally an animal significantly larger than pumas can handle.

So far, only male jaguars have been documented as coming into the U.S., and that would need to change if a self-sustaining jaguar population is ever going to establish itself in the United States. A border wall would put an end to that possibility. And that may well mean big trouble for jaguars south of the border, who won’t be able to migrate northward as the southwest’s climate continues to warm.