The border between the United States and Mexico is marked by a border wall that includes three containment barriers, motion sensors, high-intensity lighting, and more. Beyond controlling the flow of people, this wall represents an obstacle for species from both countries.
In all of them, it has been proven that animals face insurmountable barriers that separate ecosystems and habitats entirely. This situation is counterproductive for the normal development of wildlife in all its manifestations.
Study reveals impact of the wall on wildlife
Trap cameras documented an American black bear (Ursus americanus) walking for hours trying to cross the border wall between Mexico and the United States, unsuccessfully.
The spaces for the animal to cross were minimal: ten-centimeter-wide gaps between the tall steel posts or a small passage for smaller fauna than a paper sheet. There was not a single space for him, so he gave up and left.
A new study published in the journal Frontiers in Ecology and Evolution reveals that the border wall, created with the aim of halting human migration, is an obstacle that gravely impacts the movement of wild species.
The research is based on over four years of data collected by trap cameras installed along a 163.5-kilometer stretch of the border, between the northern state of Sonora, Mexico, and southern Arizona, United States.
This area, known as the Sky Islands —a region composed of 55 mountain ranges rising above arid grasslands and deserts— is a globally recognized biodiversity hotspot and is home to threatened and endangered species such as the jaguar (Panthera onca), the ocelot (Leopardus pardalis), and the Mexican wolf (Canis lupus baileyi).
The analysis of the videos collected by the organizations Sky Island Alliance and Wildlands Network, authors of the study, demonstrate that the impact is severe: only 9% of the wildlife interactions with the border wall resulted in successful crossings.
This represents an 86% reduction in crossings compared to barriers to prevent vehicle passage and a 100% reduction in crossings of large animals such as black bears, pumas, and deer.
“We have more bee species and more mammals in the Sky Islands than anywhere else on the continent,” says Eamon Harrity, a biologist and wildlife program manager for the Sky Island Alliance organization.
“One reason we have so much biodiversity is the connectivity between the mountains, but we have the wall cutting through them; that will cause us to lose animal movement,” the specialist argues.
The ecology of this region is very sensitive to disturbances and is strongly impacted by an increasingly warm and dry climate. Myles Traphagen, Borderlands program coordinator at Wildlands Network, points out that natural migration and movement corridors in western North America, and specifically in the border region, are mostly north to south.
“Therefore, a border barrier running from east to west is particularly harmful to connectivity across the continent because it limits the essential movement corridors that wide-ranging species, such as jaguars, black bears, and pronghorns, need to adapt and thrive in a dynamic environment prone to extreme climate variations,” the scientist describes.
The wall: an obstacle for species
The research points out that wildlife movements have not been considered a priority during the construction of border barriers, so a wall of this magnitude forces animals to travel long distances to find water, food, and shelter, expending more energy and exposing themselves to greater risks.
The researchers installed 36 trap cameras —operating 24 hours a day and capturing 20-second videos each time they detect wildlife movement— between the Patagonia Mountains, near Nogales, Arizona, and the San Bernardino National Wildlife Refuge, near Douglas, Arizona.
With this, they collected and analyzed almost 13,000 videos of 20 large wildlife species to understand their ability to cross border barriers.
According to the study, there were 9240 events where wildlife was recorded by the cameras, but there were only 1920 events where a successful crossing occurred.
Have you checked out our YouTube channel yet? Subscribe now!
