Photo: Steve Hillebrand /USFWS
No matter where you stand on the issue of the border wall between the United States and Mexico, we can all agree that the deleterious harms a border wall could have on wildlife is not getting the attention it should. Barriers currently cut across roughly 40 percent of the nearly 2,000-mile long border. The Secure Fence Act of 2006 precipitated the addition of a variety of fencing types, concrete vehicle barriers and sensors.
Researchers found that where barriers are already in place, wildlife is impaired. Impacts include disrupting their migration patterns and limiting the dispersal of populations, which promotes inbreeding between subpopulations of a species. The U.S. Fish and Wildlife Service predicts a wall may negatively affect 111 endangered species, such as jaguars, ocelots, jaguarundi and Mexican wolves, and 108 migratory bird species, including sparrows, warblers and hummingbirds. Four wildlife refuges, such as Lower Rio Grande Valley, Buenos Aires and Santa Ana National Wildlife Refuges, and fish hatcheries could all be negatively impacted.
These protected species and all animals should be able to access food, water and safe habitat. Walls and fences already in place are destroying the habitat connectivity that wild animals depend upon to fulfill these basic needs. Essential migratory routes may span from country to country, as a means for animals to access appropriate habitats in different seasons. A herd of bison, for example, is known to visit a pond on Mexico’s side of a barrier—as it is the only year-round water in the area—and cross into the U.S. to feed on native grasses.
The ability to roam is important since access to mates and a healthy-sized population maintains genetic diversity. Walls and fences prevent animals from following natural migration patterns and divide healthy-sized populations, leading to inbreeding and a loss of genetic diversity. Resulting mutations can eventually weaken species, making them more vulnerable to diseases and disasters such as floods, fires and climate change.
North America’s cat species are among the species most imperiled by current and future barriers. Any hope for jaguars to repatriate part of their former U.S. range depends upon any remaining jaguars in the U.S. having access to jaguars in Mexico. Few ocelots still reside in the U.S., and a fence separates them from a larger, more genetically diverse population in Mexico. Jaguarundis have been protected in the U.S. since 1976, but the last known individual died on a Texas road in 1986. A population south of the border is the only hope for this species to again flourish in its former U.S. range.
Only around 100 Mexican gray wolves remain north of the border and a few dozen south of the border. Passing across the border is essential for the two populations to maintain genetic diversity. The ferruginous pygmy owl depends upon mating between populations in Arizona and Mexico, but only flies as high as 4.5 feet. The proposed height for a new wall would be impassable for many species.
Much is at stake for wildlife as well as the integrity and health of habitats situated on the borderlands. If it is decided that the expansion of the wall must happen, wildlife biologists and others must be consulted to guide the process so that any foreseeable harms to wildlife are minimal and habitat connectivity is preserved and restored wherever feasible. We need to explore creative options such as designing wildlife crossings, leaving gaps in barriers for small animals, and having removal barriers to allow for migration or breeding seasons.
When constructing national policy, there are many important issues facing decision makers, but we should take the needs of animals and conservation into account as well. Congress and President Nixon did as much in enacting the Endangered Species Act in 1973. “We abuse land because we regard it as a commodity belonging to us,” wrote Aldo Leopold. “When we see land as a community to which we belong, we may begin to use it with love and respect.”
Ben Callison is president of the Humane Society Wildlife Land Trust