The hedges I dig on in the eastern U.S. are full of life, unlike the dense suburban variation that can be seen above.
In the eastern U.S., farm hedges often start with farmers stringing barbed wire from one tree to another, or perhaps the hedge starts as a regular post and barbed wire fence line that is not trimmed or maintained. Either way, as soon as wire is strung, trees and brush grow up underneath in a loose thicket of black walnut, black cherry, multiflora rose, and sumac is pruned and shaped by grazing deer, winter weather, and perhaps the occasional chain saw.
And what happens next? Soon enough groundhogs are likely to show up, and with them fox, raccoon, and possum who find make their dens in their all-too convenient burrows.
In short, it's not an accident that in the eastern U.S. terrier work is so often done next to rotten fence posts and rusted barbed and pig wire fences.