The low rustle of sage, the far-off clink of rock against rock, and the abrupt, sharp call of a blue-and-gray bird announcing itself before you’ve even noticed it all contribute to the unique silence that descends upon scrubland in the early morning. The American Scrub-Jay is not a timid animal. Researchers have compared its memory to that of certain primates, and it is assertive, territorial, and surprisingly intelligent. However, it is unable to get past nine feet of steel bollard fencing with four-inch gaps. And that seemingly minor restriction is starting to take on a much more serious appearance.
Due to the recent acceleration of border wall construction along the U.S.-Mexico border, conservationists have directed much of their public attention toward the large and obvious, such as black bears, mountain lions, and bighorn sheep. These are the species whose images go viral, whose suffering is shared and reposted. The American Scrub-Jay, for example, is a species of bird that doesn’t migrate in the conventional sense and depends on linked patches of scrub habitat to find mates, establish territory, and maintain genetic diversity across populations. This is the more subdued story, the one that ecologists are becoming more concerned about.
By no means is the Scrub-Jay a strong flier. Instead of moving above its habitat, it usually moves laterally and low. The behavior just doesn’t match how the bird actually moves through a landscape, even though it can theoretically fly over a wall. It comes after the scrub. It remains near the cover. A “behavioral barrier,” which the bird avoids even in the absence of a physical wall, is created by construction noise, cleared brush, and recently exposed ground, according to researchers. This pattern has been repeatedly documented in the ecological literature on border wall construction: the disturbance footprint goes well beyond the actual footprint of the wall.
Motion-triggered cameras positioned over 160 kilometers along the Arizona-Sonora border have been used in research published by organizations such as Sky Island Alliance and Wildlands Network to document the extent to which the more recent steel bollard walls serve as hard stops for the majority of terrestrial species. The wall has more behavioral and genetic effects than physical ones for some birds. When isolated from nearby populations, a Scrub-Jay does not perish at the wall. It simply stops exchanging genes with what was once a cohesive community, and over generations, that isolation builds up in ways that are more difficult to capture on camera but no less real.
The effects on any one Scrub-Jay population might not be apparent for decades. That’s one of the reasons this discussion is so challenging in a time of brief news cycles. A dramatic image is not produced by population fragmentation. In the same way that a young Peninsular bighorn was discovered dead in the Jacumba Wilderness during earlier wall construction, there isn’t a lamb wandering through a construction zone dehydrated and separated from its mother. If the Scrub-Jay declines, it will appear statistical rather than catastrophic.
The fact that minor interventions have worked for other species makes the situation especially frustrating for researchers. Modest wildlife passages, which are openings about the size of a sheet of paper placed every quarter mile, significantly increase the crossing rates of badgers, coyotes, and even young mountain lions, according to camera data. There are currently thirteen of these passages spanning over 130 kilometers of continuous wall. Thirteen. You don’t need to be a wildlife biologist to find the math problematic.
By any honest ecological accounting, the wider border region is exceptional terrain. The border between the United States and Mexico crosses six different ecological zones and divides the ranges of more than a thousand native animal species. This diversity didn’t emerge in a vacuum; rather, it evolved as a result of changes in the habitat, the land, and the animals. The borderlands are treated as though they were always intended to be divided by the wall as it is currently constructed and growing. They weren’t.
Researchers believe that when border security is the framing, the Scrub-Jay’s situation lies on the brink of what anyone is willing to publicly debate. Politically speaking, it is more difficult to defend a bird than a wolf. However, the species serves as a helpful reminder that conservation is about more than just charismatic animals. It’s the hallway. It doesn’t just mend when the political wind changes once it’s broken.
