Future Tense

Horses and Cattle Are Destroying a National Park on the Border

Stopping them requires a softer border, not a harder one.

A muddy river surrounded by mountains and desert scrub.
The Marufo Vega hiking trail in Big Bend National Park on the bottom right, a popular place to encounter illegally grazing horses. The Sierra del Carmen mountains grace the Mexican side of the Rio Grande, which is the international border. Margret Grebowicz

One of the most demanding and spectacular day hikes inside Big Bend National Park in Texas is a trail called Marufo Vega. The 14-mile loop, rated strenuous, requires always moving in order to ensure being back at your car at sundown. It’s exhausting, scenic, and very satisfying, not least because I have never encountered another human on it.

I have always, however, encountered a few horses. As you near the Rio Grande, which is also the border with Mexico—though you’d never know it, since this is one of the park’s most remote and beautiful vistas—you can usually spot at least one horse, silently grazing on the mountainsides and watching from a safe distance.

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I first thought the horses were mustangs, since truly wild horses live in habitats that look much like this all throughout the intermountain West. According to Raymond Skiles, who worked as the park’s wildlife biologist for 31 years, visitors generally report being happy to see loose horses on their backcountry hikes, often because they take them to be wild. But these are domestic horses belonging to the vaqueros—Spanish for “cowboys”—who live just on the other side of the border. They are actively herded across the river on a regular basis, and have been for decades. The lush, arid grasslands of the Chihuahuan Desert, which the park restores and protects, naturally make for the best grazing for hundreds of miles around. Both the grazing and the cross-border herding, which requires the vaqueros to enter the U.S., are against U.S. law.

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Most trespass livestock, as they are called, wear indicators of their status as farm animals—ear tags, horseshoes, bells—like the cows I encountered driving down the Ross Maxwell Scenic Drive, one of the park’s highlights. In recent decades, aerial counts have shown a minimum of about 100 farm animals inside the park on any given day. All have been found to come from ejidos, unfenced community lands in Mexico, or from larger private Mexican ranches.

The damage that illegal grazing is causing is among the most significant and intractable threats to the park’s natural and cultural resources, according to park superintendent Bob Krumenaker. In 2018, Skiles coordinated an extensive management plan to address what is effectively a low-grade, continuous emergency.

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Big Bend is not only home to threatened native plants like the Guadalupe fescue, a perennial grass on the endangered species list, but it is also a critical habitat for the yellow-billed cuckoo and home to other endangered native animal species, like the Rio Grande silvery minnow and the Mexican long-nosed bat. As they trample inside these habitats, the trespassing farm animals damage soil crusts and cause erosion. In some spots they create networks of trails, called terracettes, in which soil conditions are highly altered and plants are killed off. Other animal trails pass through historic and archaeological sites and end up destroying ancient structures. The livestock also carry the seeds of invasive species in their feces, including the extremely invasive buffelgrass, which has the potential to turn biodiverse deserts into grass monocultures.

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The burned remains of trees with scrub on a desert landscape.
Burned trees remain from a trash fire started on the Mexican side of the Rio Grande in May 2019, which spread to the park. Fresh cow dung is in the foreground. Margret Grebowicz

So why does illegal grazing continue? How hard can it be to apprehend a cow or a farm horse, after all? How could such extensive damage be going unchecked in a place as carefully managed and studied as a national park, in an area as heavily policed as the southern border?

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The difficulties cannot simply be chalked up to ever-shrinking National Park Service budgets, on which the public loves to blame all park-related problems. Chief ranger Rick Gupman explains that authorities on both sides of the border have been working on the trespass livestock problem for decades, with zero long-term success. (He and the other park service employees mentioned in this article are speaking for themselves and not for the NPS.) And as with all things border-related, the answer to the question “Why isn’t it working?” depends in large part on whom you ask.

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Control measures to round up the cows, horses, and burros herded across the river from Boquillas and Santa Elena, the tiny villages on the south side of the river, have been pretty effective in the short term. These involve flyovers and aerial counts to aid in routine roundups by park rangers and U.S. Department of Agriculture agents on both foot and horseback. Under USDA regulations, the confiscated animals are quarantined and undergo veterinary inspection to meet health and disease certification requirements. All healthy cattle are sold for slaughter (unless claimed by an owner, for a fine), while healthy horses and burros are sold at auction. All sick animals are either euthanized or sold for slaughter. None of them are returned to their owners.

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But the cost of losing entire individual herds once in a while is smaller than the gain that grazing on park grass brings to whole communities in the long term. In other words, despite the financial losses, herding their cattle into the U.S. is still “worth it” for the vaqueros. And as long as this is the case, illegal grazing stands no chance of being eliminated. New livestock will continue to show up, regardless of how many are confiscated.

Is this scenario beginning to sound familiar?

A white cow amid desert scrub.
A cow with an ear tag grazing along the Ross Maxwell Scenic Drive in Big Bend National Park. Margret Grebowicz
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Introducing more severe legal or financial consequences for the vaqueros is also not the solution. It’s not hard to move cattle back and forth across the water. Residents of Boquillas, directly across the river from some of the park’s most beloved exhibits, do so daily in order to make U.S. dollars from tourists willing to pay for a photo of a horse or the privilege of getting on one. They themselves also cross multiple times a day in order to sell trinkets to tourists or to sing for money. All of these activities are against the law, but this is how the villagers have been making their living for quite some time. And Border Patrol officials have bigger fish to fry. Their job is to deal with drug and human trafficking, cartel-related border crossings that pass through border communities, into the park, and head north through the desert in hopes of reaching Interstate 10. It’s the park law enforcement rangers who are tasked with addressing both the local trinket industry and cartel-related activities. According to Gupman, they end up unable to enforce all of the laws consistently.

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A canal with green banks runs along a road, with mountains in the distance.
Daniels Ranch is a cultural exhibit that continues to be irrigated by canals—to preserve the ranch’s original character—and now offers some of the park’s best grazing. Margret Grebowicz

But this is not just because there aren’t enough rangers to do the job. Success in fighting the cartel depends in large part on maintaining good relations with the border villages and Mexican authorities. Indeed, Big Bend is an example of excellent cross-border relations, over the course of the last few decades of border upheaval and policy changes. Such good relations are key to the sustainability of small, old border-region communities. While more intense policing of Mexican farmers and more consistent roundups may seem like the best answer, a trespass livestock “crackdown” would be a challenge to implement, given what there is to lose. Park authorities are continuously faced with walking the delicate tightrope between protecting the resource and protecting their longtime, hard-won cross-border relationships. While they cannot sacrifice law enforcement for the sake of getting along, they must at the same time continue to get along.

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The border is not only “international”—it is also profoundly “local.” And in places like Big Bend, it functions as a border not only thanks to how it restricts what people can do, but also thanks to goodwill, cooperation, and communication across the boundary, over generations.

Eliminating illegal grazing is more difficult than simply tightening security. It requires creating incentives to keep Mexican cattle at home. According to Krumenaker, the key is to identify what conditions would make illegal grazing no longer “worth it” for the vaqueros, and devote aid to implementing those conditions—but neither of these falls under the jurisdiction of the National Park Service.

The only way to keep livestock out of this protected ecosystem is to ensure their better lives in their home environments. Exactly what such improvements would look like no one yet knows, but as long as policymakers continue to pump resources solely into militarizing the border, we’ll never find out. And extensive damage to one of America’s greatest environmental treasures is certain to continue, as if it were unpreventable.

Future Tense is a partnership of Slate, New America, and Arizona State University that examines emerging technologies, public policy, and society.

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