The “big, beautiful wall” that President Trump vowed again this week to build along the Mexican border won’t block just humans. Dozens of animal species that migrate freely across the international line in search of water, food and mates would be walled off.
At a time when the Trump administration has restricted communications from the Environmental Protection Agency and other agencies, federal agencies may be reluctant to weigh in on any topic in a way that appears critical of the president’s ambitions.
But outside the government, scientists who’ve studied how 670 miles of walls and fences erected as part of the Secure Fence Act under former president George W. Bush in 2006 tell stories of animals stopping in their tracks, staring at barriers they couldn’t cross.
“At the border wall, people have found large mammals confounded and not knowing what to do,” said Jesse Lasky, an assistant professor of biology at Penn State University. Deer, mountain lions, jaguar and ocelots are among the animals whose daily movement was disrupted, he said.
Trump’s proposed wall, estimated to cost between $15 billion and $25 billion, would cover parts of the border that the Bush project, which was essentially abandoned because of its cost in 2009, does not.
Research on the impact of the current barrier fence is limited because the 2006 act gave the Homeland Security secretary sweeping power to build quickly, without the need for environmental impact studies or other analysis that would show how the land would be disturbed and how flora and fauna could potentially be harmed.
While at the University of Texas, Lasky led a study on the impact of barriers published in the journal Diversity and Distributions in 2011. The study’s main conclusion was that the “new barriers would increase the number of species at risk.”
A big concern, Lasky said in an interview Friday, was that over time the populations of threatened and endangered species would decline. A wall cutting off isolated populations from those on the other side of the wall would exacerbate the problem because they couldn’t mate, at least not in a sustainable way.
“There are concerns about small populations mating with each other and inbreeding, and getting genetic disorders from inbreeding,” Lasky said. Their problems wouldn’t end there. “We didn’t talk about it much in the paper, but with climate change, if an animal or any organism is going to stay in the temperatures it prefers, it has to move to track those conditions. That’s going to be important for the persistence of a lot of species.”
A 2008 study mentioned the decline of carnivores, such as the grizzly bear and gray wolf, at the U.S.-Mexico border and renewed interest in protecting Neotropical cat species there. “In the U.S.A., there are no known breeding populations of jaguars and only two…populations of ocelots,” according to the study by scientists at Pace University in New York and the Universidad Autónoma de Querétaro in Mexico.
The cats “are threatened by land development and land conversion, predator control by cattle growers, an increase in disease exposure, construction of highways, international bridges and immigration-control infrastructure,” meaning border walls. More walls would greatly magnify the threat, the researchers said.
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