President Trump’s proposed border wall hasn’t even been built, but ecologists say the projected impact is certain: threatening as many as 111 endangered species, especially the jaguar.

The jaguar, which was presumed extinct in the U.S. until just a few decades ago, can’t survive without access to both the American and Mexican sides of the border. But Trump has made impenetrability a requirement of any proposals to build the wall.

The jaguar just began to expand its range into the United States from the population’s main breeding grounds in the Mexican state of Sonora. While the wall wouldn’t affect the Mexican jaguar, the nascent population in America — estimated at just three male jaguars — needs a range of hundreds of miles to continue breeding.

VICE News traveled to Arizona and into Mexico to learn more about the possibility of extinction for jaguars.