January 1, 2012
by Scott Shalaway
For better or worse, wildlife populations pay no attention to human political borders. State lines certainly make no difference to coyotes or white-tailed deer crossing back and forth between Pennsylvania and Ohio.
Along the U.S.-Mexico border, it's a different story.
Walls and fences that stretch intermittently along the nearly 2,000-mile international border are intended to keep illegal immigrants out of the United States. Based on news reports, they are not terribly effective. Long, sophisticated tunnels seem easy to build. And a 2009 government report revealed that there had been 3,363 breaches of the fence January through May of that year.
But under the heading of "unintended consequences," border fences are proving to be very effective at disrupting the movements of wildlife. The current issue of The Wildlife Professional, a publication of The Wildlife Society, reports that endangered species such as jaguars, ocelots, Sonoran pronghorn and many smaller, less glamorous species are being disturbed.
In the name of homeland security, we seem to be doing our best to destroy border wildlife populations. In 1996, the Illegal Immigration Reform and Immigrant Responsibility Act required portions of the fence to be cleared of all vegetation within 50 feet of either side of the fence. So even if animals try to find a way through the fence, they must do so without any cover.
In 2005, the Real ID Act authorized the waiver of any laws that might delay construction of barriers along the California border.
Consequently, the Endangered Species Act, the National Environmental Policy Act, and the Migratory Bird Treaty Act have all been ignored in the name of national security.
And since passage of the Secure Fence Act in 2006, more than 30 federal laws, including the Clean Water Act and the Wilderness Act, have been waived.
The impact of waivers of environmental laws is still being studied, but it is clear that border wildlife populations are suffering. In one study using cameras and radio collars, bobcats influenced by fences moved their territories and experienced more collisions with highway traffic.
Fences restrict movement and gene flow and induce stress. Biologists fear that species with dwindling U.S. populations will suffer as access to Mexican populations disappears. Long-term survival of U.S. populations of larger species such as jaguars and ocelots is in doubt.