26-04-2025
Walling off the US-Mexico border would be 'catastrophic' to wildlife, researchers say
The wall at the United States' southern border disrupts ancient migration corridors, which researchers say threatens species like mountain lions, black bears, bighorn sheep, pronghorn, whitetail deer and mule deer, wild turkeys, desert tortoises and Mexican gray wolves.
'There are animals trying to cross as if their life depended on it,' Sierra Club researcher Erick Meza told attendees at the Society of Environmental Journalists' 34th Annual Conference in Tempe on April 25. 'Finding them dead at the feet of the wall is common.'
Southern Arizona zoologists from Wildland Networks, Sky Islands Alliance and Sierra Club have been monitoring wildlife in the borderlands since 2020 to try to understand what happens when nearly 70% of the border is blocked off by a wall that's up to 30 feet tall.
In 2022, cameras picked up a wolf that came out of the Gila River from the north that kept on pacing back and forth for three days along the border wall, but, unable to cross it, ended up going back where he came from and dying.
But that wolf isn't the only animal severely impacted by the 760 miles of barrier separating the United States and Mexico, which almost blocks off an entire continent, those zoologists explained.
'All these species do not fit through the openings in the wall,' Harrity said. 'Jaguars won't get through either.'
If the United States wants to reestablish a population of jaguars, there cannot be a wall, journalist John Washington said.
The wall's design — steel bollards spaced 4 inches apart or solid panels—prevents most animals larger than a bobcat from passing. Small 8.5-by-11-inch openings have allowed some female mountain lions to squeeze through, a feat researchers call remarkable but insufficient.
'For many species, those openings are the only way through the wall,' Sky Islands Alliance zoologist Eamon Harrity said. 'But there's only 19 in the entire barrier.'
At the San Bernardino National Wildlife Refuge in Arizona, Wildlands Network zoologist Myles Traphagan observed many animals before the construction of the wall, but very few after.
'One skunk out of 1641 pictures,' he said, noting ancient watersheds were bulldozed. 'I mourn that damage, like if I had lost a loved one.'
The Sierra Club in 2021 sued the Department of Homeland Security. The lawsuit secured open floodgates for two years at San Bernardino National Wildlife Refuge, more little wildlife openings, some funds for conservation science and habitat restoration, and engagement in environmental planning before further wall construction.
However, challenges remain. The Department of Homeland Security controls wall modifications, and the Trump administration could restart construction.
Researchers recently learned that the new administration wants to build across the 27.5-mile-long San Rafael Valley, considered the last network of wildlife connectivity at the southern border.
The "Sky Islands," tall mountains in the Sonoran Desert where the San Rafael Valley lies, are one of the most biodiverse places on the planet. They are the northernmost range of the jaguar, and the place where many species' northernmost and southernmost extents of migration range happens, the zoologists said at the conference.
'If we block this, it's forever. We are going to lose so many species,' Harrity said. 'Driven north by warming climates, species will run into a barrier that will prevent them from reaching climate refugees.'
The zoologists repeatedly described that outcome as 'catastrophic.'
But until the San Rafael Valley and the 63 miles of the Tohono O'odham Nation remain unwalled, there remains some hope for wildlife.
Natasha Cortinovis is a master's student at the University of Arizona, and is part of a student newsroom led by The Arizona Republic.
Coverage of the Society of Environmental Journalists conference is supported by Arizona State University's Cronkite School of Journalism, the University of Arizona and the Arizona Media Association.
These stories are published open-source for other news outlets and organizations to share and republish, with credit and links to
This article originally appeared on Arizona Republic: Researchers: Border wall expansion would be 'catastrophic' to wildlife
