Big horn sheep populations are being restored to several areas of their former range. There used to be only 2000 bighorn sheep left in Nevada and now there are 11,000. There are challenges, but this is an encouraging conservation story.
http://www.nytimes.com/2014/01/07/science/earth/a-symbol-of-the-range-returns-home.html?ref=science
http://www.nytimes.com/2014/01/07/science/earth/a-symbol-of-the-range-returns-home.html?ref=science