Wildlife Where wildlife is up against the wall Donald Trump’s proposed border wall would devastate migrating animals.

The Santa Rita Mountains, a chain of forested peaks that rise from the desert southeast of Tucson, Arizona, rank among the Southwest’s premier biodiversity hotspots. The region’s most notable resident is a 160-pound, Mexican-born male jaguar called El Jefe, who was first spotted on American soil in 2011. While El Jefe rules the Santa Ritas, he’ll likely have to return to Mexico to produce an heir. The United States hasn’t hosted a verified female jaguar since 1963.

For El Jefe and the border’s other wild inhabitants, searching for love is a complicated proposition. The United States shares a 2,000-mile border with its southern neighbor, nearly 700 miles of which is blocked by fences and vehicle barriers. Still, it remains relatively crossable for wildlife; some stretches of the Santa Ritas, for instance, are too rugged for fencing. But the border’s permeability to animals may not last.

Arizona Game and Fish

On Jan. 25, President Donald Trump signed an executive order calling for “the immediate construction” of a border wall to deter illegal immigration. Such a wall was, of course, the central plank in Trump’s campaign, and it remains as inhumane, ineffective and expensive an idea as ever. Mexico’s about as likely to pay for it as Trump is to release his tax returns. There is, of course, yet another reason to oppose the Great Wall of Trump: It will be a catastrophe for the natural world.

For decades, scientists have understood the importance of habitat connectivity to conservation. Species from wolverines to salamanders require not only protected areas to thrive, but also safe passage between them. Wide-ranging elk need to migrate from summer to winter range; isolated animals like El Jefe have to find mates; and secluded populations must mingle in order to avoid inbreeding. Today, biologists nationwide emphasize linkage: Witness the Path of the Pronghorn, America’s first federal migration corridor, or the Forest Service accounting for connectivity in planning rules. E.M. Forster’s injunction to “Only connect!” ruled the zeitgeist — until President Trump.

There is copious evidence that suggests Trump’s wall would damage borderlands ecosystems. One 2011 study found that some native species in California have already lost up to 75 percent of their range to border fences. An Arizona camera-trap study found that border infrastructure impeded the transit of cougars and coatis, but failed to affect the movements of human beings. Journalists have reported watching bison trample fences to reach food and water. A recent global review reported that barriers “curtail animals’ mobility, fragment populations and cause direct mortality.”

All told, an analysis conducted by Outside Magazine using a U.S. Fish and Wildlife Service planning tool suggests that President Trump’s wall could affect more than 100 threatened or endangered species. Might the Endangered Species Act, America’s toothiest environmental law, pose a stumbling block to this grandiose project? Section 7 of the ESA requires federal agencies to consult with Fish and Wildlife on projects that could jeopardize endangered species or destroy critical habitat. Yet a 2015 analysis found that Section 7 consultations hadn’t stopped or extensively altered a single project since 2008. The act won’t dent Trump’s wall, especially since the Department of Homeland Security has waived the law to expand border fences in the past.

At times, bemoaning Donald Trump’s harm to wildlife can feel a bit like complaining about the Titanic’s house band. His presidency is bringing near-daily affronts to his fellow Homo sapiens. He’s signed executive orders that will impair the health of women, ban certain refugees, and jeopardize Americans’ retirement money. Heck, the wall isn’t even his worst insult to animals: His vows to withdraw from international climate treaties stand to doom more species, by accelerating global warming, than any barrier ever could.

Yet the wall is a crisis, a towering symbol of Trump’s disdain for science, stewardship and environmental process. His hiring freeze will make it harder for federal agencies to manage natural resources, his plans to neuter the Environmental Protection Agency will make our air and water dirtier, and his expunging of global warming from the White House website bodes ill for our climate. He’s also empowering a Congress that’s already discarding stream protection and gas-flaring rules left and right.

Around the country, cadres of scientists have already taken stands against this benighted attitude — some by vowing to run for public office, others by going rogue on social media. Most promising is the March for Science, an upcoming protest in Washington, D.C., that thousands of scientists have pledged to attend. We can only hope that at least one marcher will be walking for connecting habitats and against the wall.

High Country News. He is a freelance journalist who covers wildlife conservation and fisheries management.

Note: This article has been updated. An earlier draft was posted, due to an editing error. Also, this article has been updated to clarify that the analysis on species impacted by the wall was conducted using an FWS tool, but was not conducted by FWS itself.

