[6] Protected as a state park since 1977, the island near Big Arm Bay is home to abundant wildlife including bighorn sheep, mule deer, waterfowl, and bald eagles.

[7] Between 1910 and 1915, homesteaders on the island cut down much of the old growth trees and introduced non-native grasses and other plant species.

As of 1987[update], when two bighorns were brought from Lincoln County, a total of ten sheep have been relocated to the island.

[10] Three of the top five bighorn sheep recorded by the Boone and Crockett Club during the three years 2015-2018 came from Wild Horse Island.

[3] A study conducted over a 25-year span has shown the average yearly precipitation on Wild Horse Island to be 15.7 inches (400 mm).