Now all we need for the wall is a video image recognition system similar to what Apple uses in iPhone X to recognize faces, except this will recognize animals and humans. 
If it’s a lonely little prairie dog or a deer chased by a mountain lion, a gate will open to allow them to pass. If it’s not, and stands on two legs like a human, the barrier stays closed.
The French had a super-high frequency RADAR that could differentiate between a mule and a human, and used it in Vietnam to keep out undesirables. Perhaps that’s what we need on our  border.