Experts issue urgent warning over unintended consequences of US-Mexico border wall: 'If we block this, it's forever'

If plans to complete the border wall between Mexico and the United States are realized, irreversible harm could be done to dozens of endangered species.

What's happening?

The U.S.-Mexico border is nearly 2,000 miles long and stretches across four states. In March, the current administration indicated an intention to finish the wall's construction by 2029. Aside from the enormous cost and questions of its efficacy, one of the biggest concerns is the environmental impact.

The Sky Islands are a remote mountain range in southeastern Arizona, described by an article in The Travel as having "more biodiversity than any other inland region in the United States." If this critical biodiversity hot spot is walled off, several species face extinction. Sky Islands Alliance zoologist Eamon Harrity warned: "If we block this, it's forever. We are going to lose so many species."

Why is a border wall such a concern for wildlife?

The U.S.-Mexico borderlands are home to several migrating species, including black bears, mountain lions, ocelots, and jaguars. They rely on wildlife corridors to travel freely between the countries in search of food, water, and mates.

In areas with standing barriers, the wildlife suffers. With only a limited number of openings for animals to cross through the obstacles, most will either avoid them or try to go around them. A study revealed that only 9% of attempted animal crossings are successful.

Habitat connectivity is vital for the long-term viability of a species. Without it, animal populations become isolated, inbred, and vulnerable to the impact of food scarcity and extreme weather events. It also closes the door on the revival of particular species in the future. For example, as Panthera noted, jaguars once roamed the southern United States but have since been effectively extirpated from the region; a completed border wall would guarantee that the species could never return to the region.

What's being done to protect borderlands wildlife?

The proposals are still a long way from being realized, and there's a great deal of scope for taking local action to counter the damage that could be done. Similarly, just as bipartisan pressure prevented the sale of public lands, it can work again to protect species in the borderlands. Backing pro-climate political candidates is another way to safeguard the unique biodiversity of the Sky Islands.

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