Trump’s Wall Threatens Thousands of Plant and Animal Species Along the U.S.-Mexico Border

January 10, 2019 at 1:49 am





Around 50 threatened animal species — including jaguars, ocelots and bighorn sheep — will struggle to survive if the wall is built




The 2,000-mile border between the United States and Mexico cuts through some of the most ecologically diverse wildlife habitat on the continent.

That’s because there are 25 million acres of protected public lands within 100 miles of the border. That includes six wildlife refuges, six national parks, tribal lands, wilderness areas, and conservation areas.

About a third of the border has already been fenced off, isolating and reducing populations of some of the rarest and most amazing animals in North America, like the jaguar and ocelot. Walling the entire border off would interrupt migration routes and could spell extinction for many of these creatures, environmental groups warn.

While many of us imagine the border as a desert wasteland, the area where Arizona and New Mexico meet Mexico is one of the the largest protected landscapes in North America with temperate and semi-tropical climates.

The region includes the Sky Islands, an isolated mountain range in the Sonoran desert. As elevation increases there, “shrubs and cacti give way to oak, juniper and pine, spruce and fir,” writes Cally Carswell for The Scientific American.

“Large mammals like black bears, mountain lions and bighorn sheep live in these mountains, along with a flabbergasting number of birds. More than 7,000 plant and animal species make their homes here, and more than half of the bird species found on the entire continent inhabit the Sky Islands.”

Most of the “Sky Islands” fall within the Coronado National Forest, which is home to the greatest number of threatened and endangered species of any national forest in the US.


Those species include jaguars, thick-billed parrots, spotted owls, barred tiger salamanders, Mount Graham red squirrels, and many other unusual species.

New walls through the Lower Rio Grande Valley could further isolate the few remaining populations of ocelots in the US. Arterra / UIG via Getty Images

Additionally, the Department of Homeland Security is eyeing unfenced areas in two Texas wildlife refuges that conservationists consider some of the most ecologically valuable areas on the border — home to armadillos and bobcats, Vox reports.

To find food and water, animals need freedom to move, explains Scott Wilbor, conservation science director for the Sky Islands Alliance. “They’re constantly following the rain patterns.”

Additional barriers to their movement (on top of the scattered fences that already exist) could lead to extinction for many species.

A 2011 study estimated 134 mammal, 178 reptile, and 57 amphibian species live within about 30 miles of the border. Of those, 50 species and three subspecies are globally or nationally threatened.

The endangered Sonoran pronghorn, already avoids fencing of any kind, even single bars they can easily scoot under, says University of Arizona wildlife ecologist Dave Christianson.

Other species likely to be vulnerable to border barriers include bighorn sheep, ferruginous pygmy owls and black bears, he says. Genetic research on black bears shows populations in southern Arizona are more closely related to bears in Mexico than those in northern Arizona. Because their populations are already small, barriers could lead to inbreeding, increasing the risk of local extinction.

Similarly, a 2009 study showed a significant amount of gene flow between bighorn sheep in the U.S. and Mexico. A barrier would disrupt this network,

Even birds can be affected, says Aaron Flesch, lead author of the study and wildlife biologist at the University of Arizona.

Flesch found pygmy owls rarely took flight at heights lofty enough to clear border fences and avoided large gaps in vegetation, which are common near the barriers.

Some sections of fencing have lights that attract and zap pollinators, like the disappearing monarch butterfly.

The taller the fence, the more difficult it is for bats and birds to clear.

The same is true for jaguars. At this point, the cats are functionally extinct in the U.S. An unbroken wall would seal their fate. “It would basically give us no avenue for recovery,” Flesch says.

Like wolves, jaguars need anywhere from 10 to 50 square miles to roam.

“There are also tropical animal species in some of these canyons that are not found anywhere else,” says Jesse Lasky, a biologist at Penn State who has studied the impact of border fences on border species. “They inhabit these little slices of tropical ecosystem that creep up into the US near the Gulf coast.”