I decided to stay on this section of the border today, so got a picture of one of the "cat gates" cut into the border fence after the fact to allow all but the biggest wildlife to pass through. Keep in mind though that there are only 24 of these in 20 miles. Not near enough.
My foot in the lower part of the frame for scale.
The standard gap between the bollards (what the posts are called) is 4 inches.