Bighorn sheep, Zion National Park, 2015.

Bighorn sheep (Ovis canadensis) originally crossed into North America over the Bering land bridge from Siberia. The population peaked in the millions and bighorn sheep entered into the mythology of Native Americans. Unfortunately, by 1900 the population had crashed to just several thousand due to diseases spread through the introduction of European livestock and overhunting. Conservation efforts have restored the North American population. About 42 years ago, Zion began a project to reintroduce bighorn sheep to the park. In July of 1973, 12 bighorn were brought to the park. Though considered only marginally-successful at the time, the herd has since flourished to an estimated 800 animals.