Somewhere in the rugged borderland sky islands of Arizona, a single jaguar — known to scientists and trackers as El Jefe's successor — navigates the rocky scrub of what remains of his ancestral range. He is, by every available estimate, among the last of his kind in the United States. The corridor he depends upon, threading through the Coronado National Memorial and the vast borderland wilderness between Arizona and Sonora, Mexico, is now being severed — by steel, by concrete, and by a legal mechanism that explicitly removes the requirement to ask whether any of this matters for the wildlife it destroys.
The Trump administration's accelerated border wall expansion has reached inside national park and protected public land boundaries, according to reporting by SFGate, advancing construction through ecologically critical terrain without the environmental impact reviews mandated under the National Environmental Policy Act (NEPA) and the Endangered Species Act (ESA). The mechanism enabling this is a sweeping waiver authority — originally embedded in border security legislation — that allows the Department of Homeland Security to set aside dozens of environmental and historic preservation laws in the name of expediting construction. It has been invoked before. It is being invoked again, at a scale and pace that conservation biologists describe as alarming.
The Jaguar Corridor: America's Last Lifeline
The jaguar — Panthera onca — once roamed from Patagonia to the Grand Canyon. Decades of hunting, habitat loss, and the fragmentation of the borderland wilderness reduced the US population to effectively zero for most of the twentieth century. Then, beginning in the 1990s, camera traps began capturing something extraordinary: individual male jaguars crossing north from Mexico, drawn by deer, javelinas, and the rugged mountain habitat of southern Arizona and New Mexico.
The Huachuca Mountains, the Peloncillo Mountains, and the broader Sky Island archipelago form the critical pathway. This corridor is the only route by which jaguar recovery in the United States is biologically possible — the only geographic thread connecting the viable breeding populations in Sonora to the habitat that could, with sustained protection, support a recovered US population. The US Fish and Wildlife Service formally designated critical habitat for the jaguar in the Southwest in 2014. That designation carries legal weight — or it did, before ESA waivers entered the picture.
A border wall is not merely a physical barrier. For a wide-ranging carnivore like the jaguar, a continuous steel structure topped with sensors and floodlit at night is functionally impermeable. It does not just block individual movement — it severs the genetic exchange between populations that evolutionary biology requires for long-term species viability. A US jaguar population cut off from Mexico is not a recovering population. It is a population awaiting local extinction.
Beyond the Jaguar: Pronghorn, Ocelot, and the Broader Collapse
The jaguar captures headlines, but the ecological wound being opened by unreviewed barrier construction runs far wider. Sonoran pronghorn — one of the rarest mammals in North America, with a US population numbering only in the hundreds — depend on seasonal movement across the Cabeza Prieta National Wildlife Refuge and Organ Pipe Cactus National Monument. Existing barrier infrastructure already forces pronghorn into suboptimal habitat; each new section of wall narrows their viable range further.
The ocelot, another federally endangered cat, clings to existence in the borderland scrub of south Texas and Arizona with a US population so small that individual animals are known by name to the biologists monitoring them. Ocelots require dense brush cover and connected habitat patches — precisely the landscape that construction access roads, floodlighting, and barrier clearing destroy before a single steel post is set.
Migratory songbirds, reptiles, and a remarkable suite of pollinator species also cross what ecologists call the Sky Island biodiversity hotspot — a region of extraordinary biological richness precisely because the complex terrain and climatic gradients have supported the co-evolution of species across millennia. Walls do not honour biodiversity hotspots.
The ESA Waiver: A Legal Mechanism With No Ecological Logic
The endangered species protections being waived were not bureaucratic impediments. They were the scaffolding through which jaguar critical habitat was identified, mapped, and legally shielded. Invoking the waiver does not make that habitat less critical — it simply removes the legal requirement to consider the consequences before destroying it.
Conservation attorneys have challenged the waiver authority in federal court before, with limited success. The statutory language granting DHS waiver power is broad, and courts have generally declined to second-guess national security determinations. What remains is political accountability — and the pressure that an informed public can apply when it understands what is being traded away and for what.
What Is at Stake
The jaguar's return to Arizona was one of the most improbable conservation stories of the late twentieth century. A species hunted to regional extinction began, tentatively, to reclaim a fragment of its former range — not because of a captive breeding programme or a reintroduction scheme, but simply because a few individual animals found a way through the borderland and followed the ancient pull of habitat northward.
That story is not over. But it is in danger of ending — not gradually, through the accumulating pressures of climate change or prey depletion, but abruptly, through the deliberate choice to build a wall through the only corridor that makes recovery biologically possible, without pausing to ask what the cost will be.
In nature, as across ecosystems, every species plays a role — and humanity's choices determine whether the web of life flourishes or frays. The jaguar does not know about ESA waivers or NEPA exemptions. He knows only the scent of deer on the desert wind, the ancient pull of mountain habitat, and a steel wall where there was none before. The question before us is whether the choices that placed that wall there were made with full understanding of what they foreclosed — and whether, even now, there is the political will to answer for it.
