Walled Off

Rio Grande Guardian
August 15, 2009
by Char Miller

CLAREMONT, Aug. 15 - Pygmy owls and Bighorn sheep make an odd couple.

These keystone species along the U.S.-Mexico border have little in common--their size and weight (so perfectly captured in their names), like their mode of transportation and food sources, could not be more different. Yet they share a desert habitat, and there in lies their mutual problem.

It comes in the form of the impenetrable border wall the United States is building across the southwestern states, which will inhibit their ability to move, hunt, and reproduce. How ironic that this triple-thick bulwark, which has failed miserably to stem the flow of undocumented migrants into the United States, may have a fatal impact on animals so innocent of the human politics and policies that led to its erection.

This dire situation has been the focus of the research of two conservation biologists, Aaron Flesch at the University of Arizona and Clinton Epps of Oregon State. In an article to appear in Conservation Biology, the scientists have explored the troubling possibilities the wall may pose to these two species’ daily life and long-term survival.

Consider the Pygmy owl’s below-the-radar flight path: most of its sorties are conducted less than13 feet off the ground, as it swoops down on its prey from its preferred perch in a secluded thicket. A wall that stands upwards of 19 feet, and whose construction requires bulldozing a wide swath on either side, thus poses serious problems for individual owls to protect themselves from their predators and to sustain themselves over time.

More complicating still is that the newly leveled ground will have a multi-generational impact. Juvenile owls need undisturbed landscapes in which to colonize, a nesting behavior that the wall’s structure necessarily will frustrate. And the breeding colonies on the American side of the border apparently require contact with those on the other. As Professor Flesch has observed: “Movement of pygmy owls from Mexico to Arizona may be necessary for the persistence of the Arizona population.”

The need for cross-border fertilization may prove even more important for the Bighorn sheep’s survival, Flesch and Aaron argue; their research indicates that there is a strong genetic link between those sheep populations living in the Sonoran mountains in Mexico and those inhabiting the southern highlands of Arizona.

Unimpeded connectivity between the two is essential because without it the different herds will become cut off, degrading their genetic diversity. “Bighorns in places like the Sonoran desert will form small populations – sometimes with only 10, 15 or 20 animals,” Epps said in a press release. “Yet they will occasionally move back and forth and mix with other groups. That connectivity is critical to their survival. Without it, they can still sometimes re-colonize, but often that small group will go extinct.” Should that occur, these sheep, like the pygmy owl, will find that human agency has sabotaged their biological imperatives.

The political impulse that built the wall in defense of U.S. borders is itself a form of territorial marking, a behavior that all species manifest; of necessity all species try to manage their habitats. The purpose of such management is to enhance their chance of survival, a process, often enough, that depends on beneficial interactions with other creatures; this mutuality is critical to the creation of sustainable landscapes and the rich biodiversity that makes them so.

But Homo sapiens also love monocultures, as our suburban lawns, big-box malls, and agricultural practices testify. Through our tools and technology we have the power to clear away competitors or build environments that diminish their odds of survival. The border wall is a monument to human hegemony.

Yet the wall’s construction is only one expression of our dominance. As contractors flatten the land; dig fence posts and hang chain-link and concertina wire between them; set up guard towers, complete with searchlights and infrared cameras; and lay down hardened roadways for high-speed patrol vehicles, they are manufacturing a new landscape with a single purpose.

The goal of this high-tech infrastructure on the ground--when combined with aerial surveillance--is to halt illegal immigration into the United States. To accomplish this mission, the federal government has spent millions of dollars; hired and trained thousands of new border guards; and has flexed its muscles in ways fiscal and physical that is designed to display its authority.

One manifestation of this is captured in the commotion that Professor Eppes describes as integral to the new habitat that the U. S. has built along the border. “The sheer number of people moving across the landscape is stunning. The crackdown on urban crossings has forced people into wild areas,” intensifying “the amount of human activity--both people crossing and the border patrols seeking them” in an arid region that once was thinly settled and rarely visited.

Bearing the brunt of this escalating human presence is the very wildlife that Flesch and Epps have been tracking. As a result, they propose a number of well-intentioned changes to the border wall’s physical structure in hopes of increasing the chance that pygmy owls and bighorn sheep will be able to survive in this trampled terrain; for the owl, they suggest maintaining tree cover along the border; for the sheep, a more open wall that will allow these them to continue their cross-border migrations. Even so, they recognize that their proposals conflict with the governmental desire to maintain an impassable barrier, and are thus a non-starter.

Indisputable is their larger, if unstated argument: to worry about the survival of wildlife, regardless of size, is to be anxious about our own.

Char Miller is director of the environmental analysis program at Pomona College, Claremont, CA., and author of Deep in the Heart of San Antonio: Land and Life in South Texas.

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