"Bighorns in places like the Sonoran desert will form small populations sometimes with only 10, 15 or 20 animals," Epps said. "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.
"Isolating populations not only reduces genetic diversity," he added, "it makes the animals more susceptible to disease, drought and other weather extremes, and predation. We've seen one or two mountain lions knock down populations of sheep once they get a taste for mutton."
The scientists say the wall along the U.S.-Mexican border is not the only issue for wildlife. Human activity, vehicular traffic, amplified noise and artificial lighting associated with the barrier can all affect how animals behave.
"There is a political reality and a biological reality to the border wall," Epps said. "We've talked to people who work along the border and the sheer number of people moving across the landscape is stunning. The crackdown on urban crossings has forced people into wild areas and the amount of human activity both people crossing and the border patrols seeking them has to have an effect on wildlife.
"Gaps in the fence could help, but that might channel more people to use those open areas for crossing, negating the benefit for wildlife and the purpose for constructing the wall in the first place," he added. "It may be time to re-examine the structure of the wall and do more research on potential outcome
|Contact: Clinton Epps|
Oregon State University