U.S. wall raises concern for Big Bend ecosystem

Advocates of park fear for its reviving species

BIG BEND NATIONAL PARK, Texas -- If it belonged to anyone, this expanse of high desert was first the domain of the nomadic Chisos Indians, who were killed off by the Apaches, who were defeated by the Spanish, who were run off by the Comanches -- until white settlers imported repeating rifles and put an end to all debate about who owned what.

Six different flags have flown over the land that makes up Big Bend National Park, but the arid Chihuahuan limestone soil resists most attempts at settlement. The Spanish called it El Despoblado, the uninhabited land. For most of its history, the 800,000 acres belonged to the wild.

Now many there are worried about what would be the most powerful territorial claim of all: a proposed wall along the U.S.-Mexico border that, if extended as far as the remote national park, would form a permanent divide along the Rio Grande.

No one knows how far beyond cities such a wall would extend, but conservationists are raising an alarm. The chief fear is that a barrier would threaten the slow but steady reintroduction of wildlife species killed off during the 19th and 20th centuries, one of the Southwest's most important environmental success stories.

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"It would completely ruin the experience of one of the most beautiful natural places left in this country," said Rick LoBello, a former Big Bend park ranger and director of the conservation group Greater Big Bend Coalition.

Taken in from nearly any direction, the park's scale is staggering. Unlike heavily forested mountainous areas, the shrubby yucca, agave and creosote provide uninterrupted views of soaring peaks, lush, high-elevation glens and the American piece of the Chihuahuan Desert, the largest in North America.

Created by a "rain shadow" effect between two mountain ranges, the Sierra Madre Occidental and Sierra Madre Oriental, the desert there was once a rich font of biodiversity, hosting species from bighorn sheep to gray wolves.

Settlers from the eastern U.S. claimed the land, first for the Republic of Texas, then for the United States, and held the area for more than half a century. They grazed their livestock on the fragile ecosystem that crumbled under the demands of raising cattle.

Grass was planted over native shrubbery, destroying the feeding stock of the area's natural predators. Undesirable plants were dug up by the acre; bats were driven from caves; bears, jaguars and wolves were shot on sight.

Then the great drought of the Dust Bowl in the 1930s drove many ranchers into financial ruin, and on the same day U.S. forces were landing on the shores of Normandy in France, on June 6, 1944, President Franklin Roosevelt signed the Big Bend National Park into existence.

The Mexican black bear, which once wandered freely through the Chisos Mountains, had been one of the casualties of the ranching era. The bears had largely disappeared on the American side of the border by the 1940s, wiped out by hunting and poisoning.

But the open border proved to be the bear's salvation. The bear survived in the Maderas del Carmen on the Mexican side of the border, and by the late 1980s, park rangers made a remarkable discovery: A black bear mother and cub had migrated to the U.S. side.

By 1999, there were 343 sightings of bears on the American side of the river. "The recolonization of black bears in Big Bend is a remarkable natural event," the National Park Service says now on its website.

But what would happen if the bears' free-range habitat, so crucial to its re-emergence, were to be split by a wall?

The answer, wildlife advocates and park officials say, would depend on the location and construction of the wall.

Placing the wall on the border itself would be difficult. According to the original agreement struck between Mexico and the United States, the border runs to the deepest part of the Rio Grande's channel as it ran in 1848, the year of the Treaty of Guadalupe Hidalgo.

"I can't even begin to predict what the impact would be without knowing the specifics" of the wall, said Big Bend Park Ranger Jeanette Juraldo.

One concern, Juraldo said, would be the impact on plants along the Rio Grande.

"If it were to be in the river or along it, certainly we have several species of plants that would be affected," she said of the wall.

As for the potential impact on the bears, "it's just basic science that a physical barrier would prevent the species from [mingling] genetics," Juraldo said.

Isolating bears on either side of the wall, aside from the disruption to their foraging, could expose them to genetic weaknesses as the two separated bands began to inbreed.

The disruption could extend beyond a physical barrier, LoBello said. Vegetation that gets in the way of construction would probably be cleared, reducing available food sources for the park's dozens of protected and endangered species, including the long-nosed bat, which relies on agave plants' dense nutrient content for its long migratory flights.

Increased human activity on both sides of the border with construction and monitoring of a wall would drive species away from a natural point of intermingling, further isolating their genetics, conservationists fear.

There are also worries that construction of a barrier would interfere with the very nature of the park, once envisioned as a binational free zone between Mexico and the U.S., although that plan never came to fruition.

"What will be the future relationship of these neighboring protected areas on the United States/Mexico border?" the park's leadership asks rhetorically on its website. "Only time will reveal the exact outcome."

Jude Hickey has no such ambiguity. He has been visiting Big Bend from his home in Austin, Texas, for a decade, and when considering the prospect of a wall dividing the river, he scoffed.

"I don't know that we could even undo that if it happened," Hickey said. "It's really just natural once. Then it's gone."

SundayMonday on 02/19/2017

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