PARIS— The Center for Biological Diversity called for “in danger” status today for a Mexican World Heritage site harmed by the U.S. border wall. The controversial U.S. wall cuts the world’s largest swath of protected desert habitat in two, walling off critical habitat connectivity.

Today's letter urges the UNESCO World Heritage Committee to recognize that the wall is gravely damaging Mexico’s El Pinacate and Gran Desierto de Altar Biosphere Reserve and its borderland wildlife.

The Trump administration completed 455 miles of the border wall, including a 30-foot-high segment across the northern boundary of El Pinacate. The wall now runs along three protected borderland areas: El Pinacate in Mexico and Cabeza Prieta National Wildlife Refuge and Organ Pipe Cactus National Monument in the United States. Only 14 mountainous miles of the border along El Pinacate are now without a barrier.

“To protect this priceless World Heritage site, the Biden administration has to tear down this wall,” said Alejandro Olivera, senior scientist and Mexico representative at the Center for Biological Diversity. “Every day the border wall stays up, it causes more harm to El Pinacate and the whole desert ecosystem by preventing wildlife from moving freely. Animals like pronghorn and bighorn sheep that have migrated across the border for millennia are now stuck on one side, sometimes unable to find food and water.”

UNESCO designated El Pinacate Reserve as a World Heritage property in 2013 in recognition of the area's outstanding biodiversity. The reserve is home to desert wildlife that evolved over millions of years, freely crossing the U.S.-Mexico border. The wall blocks essential movement and migration, fragments habitat, and limits animals' ability to find a mate and search for food and water across the harsh Sonoran Desert.

Under the World Heritage Convention, a site may be listed as “in danger” if “development projects” or “major public works” threaten the natural values the site was designated to protect. An “in danger” designation will focus international attention on El Pinacate and its habitat, as well as the ecological and cultural threats posed by the U.S. border wall.

The species obstructed by the wall include the Sonoran pronghorn, flat-tail horned lizard, Yuma fringe-toed lizard, Sonoyta pupfish, Sonoyta mud turtle, lesser long-nose and fish-eating bats, Goode’s horned lizard, mountain lion, coyotes, Mexican bighorn sheep, Sonoran desert tortoise, mule deer, jaguars, and even low-flying owls.

Preliminary survey results indicate the Pinacate population of Sonoran pronghorn declined from 126 animals in 2020 to 85 in 2022. Water reservoirs and oases have been divided and are now inaccessible to wildlife on the Pinacate side. For example, Quitobaquito Springs is now unreachable from Mexico.

The wall also harms the Tohono O'odham people, who historically inhabited El Pinacate and whose traditional lands are split by the U.S.-Mexico border. El Pinacate is sacred to the Tohono O'odham, and the site is regularly used for ceremonial purposes, including a sacred salt pilgrimage from the United States across the border to Mexico's Gulf of California.