“...in which a physical wall will impede (for instance) animal migrations.”
Or, cattle getting to the river. The gov’t is already in the process of taking private land for a “wall”. And even though a wall isn’t built yet, the ranchers aren’t able to get their cows to the water. Turns hundreds/thousands of acres of grazing land worthless if the cows can’t drink.
So true. Former farm boy myself, and raised a few cattle. Any "wall" has to conform itself to local conditions. The idea of a "one size fits all" solution is simply unfeasible in the real world.