Bighorn sheep will find a way.

How can landowners keep cattle (or sheep or other livestock) in while allowing pronghorn to migrate and tortoises to roam freely? It can be done, and the Arizona Game and Fish Department has 30 pages worth of advice and instruction on constructing a fence that can keep in what landowners want to keep in (and keep out what landowners want to keep out), while allowing wildlife passage. There is even a section on international border fencing.

While the focus is on Arizona species (pronghorn, mule deer, javelina, desert tortoises and Gila monsters), the advice can be adapted for other species and other areas of the country.

For doubters, there is even a section on the impacts of fencing on wildlife, complete with gruesome photos.

The 34-page PDF of fencing guidelines can be found here. 

Photo: Bighorn sheep will go over, under or through most fencing. Photo credit: Christine Page, courtesy of Arizona Game and Fish.