The September/October issue of Audubon Magazine contains an article about the proposed and actual fences along the border between the United States and Mexico. We recommend the article highly and it is currently available on Audubon’s website. Don’t worry, it is not a political article nor will we force-feed you our views on the politics of illegal immigration. It is; however, a good lesson in the Law of Unintended Consequences.
Especially for some rare birds. The Pygmy Owl for instance. It rarely flies more than 12 feet off the ground and dislikes open areas. The Owl is extremely rare in southern Arizona and is declining in Northern Sonora. It, and some ground dwelling birds, such as Gould’s Turkey will not be able to go over, through or under a fence. This is important because of breeding ranges.
It is also important for any number of mammals such as the endangered Sonoran pronghorn antelope, ocelots, jaguars, coati, two species of skunks, and the tiny Coues deer. For some species – very small species – like the flat-tailed horned lizard, an adjustment can be made; very small slits at ground level in the otherwise impermeable 15 foot high fence. For the others, a wall could end their existence. Animals and birds don’t do political lines on maps.
In the careful language of science:
Because populations divided by the fence would have smaller pools of prospective mates, their genetic diversity—and, with it, their ability to withstand disease, environmental stresses, and other challenges—is likely to erode.
If you really don’t have time to read the article we’ll briefly summarize it for you. In the mid 1990’s the U.S. Border Patrol began cracking down on transits through the cities along the U.S. Mexico border. This had the consequence of driving the illegal immigrants out to the Sonoran desert wildlands to make their crossings. A “pedestrian” fence all along that border is one of the proposals to stop that traffic. However, according at least to the United States Marines whose job it is to secure a portion of the border that crosses a Marine base, the pedestrian fence is unnecessary, too expensive and probably won’t work. A pedestrian fence makes sense in an urban area because the Border Patrol only has two or three minutes to catch someone who crosses before that person fades into the urban background and disappears. Even that short delay at a fence enables the Border Patrol to catch a high number of people who attempt the crossing. Out on the desert, there is no such hurry because immigrants cannot disappear. Sometimes, the Border Patrol has a week or more to track them down, assuming they don’t die first. Vehicle barriers make sense for some desert locations but not a pedestrian fence. And a Pygmy Owl can fly over a five foot high vehicle barrier.
That summary does not do justice to the article. Really, take the time to read it.
(We were unable to find the attribution for the photo of the Cactus Ferruginous Pygmy Owl which is not one of ours.)