SAN FRANCISCO (KGO) — Miles of border wall stretch into the divide the United States from Mexico. But now, there is growing evidence that newly constructed sections are also dividing a critical habitat. This is disrupting natural migrations — both of animals that eventually manage to work their way through the fence and those too large to cross at all.

“Yes, absolutely. I mean the border wall is creating a massive continental scale environmental experiment that we’re all along for the ride with. And it’s going to affect the evolutionary history of these species,” said Emily Burns, a researcher with the nonprofit Sky Island Alliance.

Over the last several years, the group has been placing wildlife cameras along sections of the border wall in Arizona to document its impact. On any given night, smaller animals, like Javelinas, can slip through small openings at the base, perhaps followed by a lucky porcupine

But the group’s cameras have also captured images of larger animals, like a black bear, which is endangered in Mexico. It was photographed as it paced along the length of the wall, searching for an opening. Even an agile mountain lion can be seen trying to get through as well.

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“And there are species that need a lot of space. Mountain lions, especially the males, once they get old enough and leave their mother, they need to establish their own territory. And they’re just looking for simple things that everybody looks for: shelter, food, mates and water. That’s what it’s all about,” Burns said.

And that extended range can be critical for long-term survival. It’s a lesson we’ve learned here in the Bay Area, where urban areas intersect with corridors of open space. Migration pathways that can stretch from areas like the Santa Cruz Mountains all the way to the Diablo Range.

Zara McDonald is with the Bay Area Puma project. Her group tracks mountain lions and other animals with wildlife cameras similar to those being used at the border. She worries about obstacles like freeways that can make it difficult for the animals to roam freely and mate.

“Basically, habitat fragmentation for mountain lions restricts movement and gene flow. And so, if a population becomes isolated, then these subpopulations cannot connect genes. And essentially what they do is they’re restricted not only in movement but in gene flow, meaning that some populations themselves, you know, are more susceptible to disease, to inbreeding. And so, genetic disorders,” McDonald said.

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Her group lobbies for land bridges or storm drain-type tubes that can make crossing dangerous areas easier and safer. Back in Arizona, the Sky Island Alliance is working on solutions for the border wall as well.

“It can be a no cost solution of just opening floodgates in the wall passageways to allow storm water to drain either way across the border. Those can be used by many animals to cross back and forth. As much as I don’t want to live with the wall in our backyard, we are. And so, our priority has to be finding creative ways that don’t jeopardize national security, but make it better for wildlife. And I think we know how to do that,” Burns said.

There’s also significant movement on the issue nationally. A lawsuit by more than a dozen states is forcing the federal government to improve wildlife corridors at the border. Here in the Bay Area, a crossing has been created in the Santa Cruz Mountains, with more planned.

This report was produced in partnership with the Local Media Association’s Covering Climate Collaborative.

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