Kiah Collier and Neene Satija have written an excellent article in The Texas Tribune about some unintended consequences of building Trump's border wall. While the wall won't stop people, it will stop the natural migration of animals of all types -- harming them, and driving many species into extinction.
It's an excellent article, and I urge you to read it in its entirety. Here is some of that article:
Muddy handprints cover the rusty, iron posts on this section of border fence in far South Texas. The 18-foot-tall barrier, which runs between a national wildlife refuge and a local nature center, ends abruptly less than a mile down the road. Still, somebody clearly thought it was best to cross here. “This is probably one of the most visible places they could have climbed,” Scott Nicol, co-chair of the Sierra Club’s Borderlands Campaign, said before snapping photos of the handprints. “I don't know if they got caught or not, but they made it up and over for sure.” There’s been a lot of debate about how effective the Bush-era barrier has been at keeping out illegal crossers and drug smugglers. Some data indicates the barriers have encouraged people to cross in places where there isn’t one. But the handprints show that a determined person can still easily scale it. What the border fence has kept out instead, according to environmentalists, scientists and local officials, is wildlife. And the people who have spent decades acquiring and restoring border habitat say that if President Donald Trump makes good on his promise to turn the border fence into a continuous, 40-foot concrete wall, the situation for wildlife along the border — one of the most biodiverse areas in North America — will only get worse. Right now, a mix of vehicle barriers and pedestrian fencing covers only about one-third of the nearly 2,000-mile U.S.-Mexico border. Even with all those gaps, experts say the barriers have made it harder for animals to find food, water and mates. Many of them, like jaguars, gray wolves and ocelots, are already endangered. Aaron Flesch, a biologist at the University of Arizona, said most border animals are already squeezed into small, fragmented patches of habitat. “If you just go and you cut movements off,” he said, “you can potentially destabilize these entire networks of population.” Still, the impacts of the border fence on wildlife aren’t totally understood. That’s in large part because Congress let the U.S. Department of Homeland Security ignore all the environmental laws that would’ve required the agency to fully study how the barrier would affect wildlife. Flesch and other scientists say the federal government also has made almost no research money available to support independent studies. Most of the studies that have been done are limited in scope, but their findings are pretty clear: Impeding animal movements puts them on a faster path to extinction. Environmentalists and conservation groups say the border fence also has compromised the federal government’s own efforts to protect those vulnerable species, pitting the U.S. Department of Homeland Security against the U.S. Fish and Wildlife Service. The latter agency bought large tracts of land along the border decades ago and turned them into national wildlife refuges. . . . At the 18-foot pedestrian fence in Hidalgo, the posts are positioned less than 2 inches apart — far too narrow for even small critters to squeeze through. Flesch’s research found that the fence also blocks the threatened pygmy owl, which can only fly a few feet above the ground. Jesse Lasky, a biologist at Penn State University who studied the impacts of the fence on mammals, reptiles and amphibians, found that the U.S.-Mexico barrier reduced the range for some species by as much as 75 percent. Impacts were particularly acute on smaller populations of wildlife that occur in more specialized habitats like the endangered jaguarundi — another small wild cat. “Mountain lions, jaguars, bobcats, javelinas, big horned sheep, deer, black bears — those animals often move far to find what they need,” he said, adding that a hardened border wall like the one Trump is proposing would be “substantially more threatening.” Another study conducted in Arizona, published in 2014, used motion-sensitive cameras to monitor animal — and human — movement along the border. The researchers found that pumas and hog-nosed coons, or “coati,” were more likely to appear in places without a barrier. But human crossers appeared in equal numbers whether there was a barrier or not. . . . Flesch, the Arizona biologist, says all the gaps in the fence have definitely lessened environmental impacts; that’s especially true in Texas, where there is only 110 miles of it. Black bears, for example, have been able to continue their recent comeback in the Lone Star State after being hunted to near extinction, and even a few jaguars — more prevalent in Mexico — have been spotted in the United States in recent years. Free movement of wildlife is especially important after droughts or natural disasters that can wipe out subpopulations, Flesch said. “The only species we know that’s going to make it through the wall are people,” he added.