The Santa Catalina Mountains, commonly referred to as the Catalina Mountains or the Catalinas, are north and northeast of Tucson in Arizona, United States, on Tucson's north perimeter. The mountain range is the most prominent in the Tucson area, with the highest average elevation. The highest point in the Catalinas is Mount Lemmon at an elevation of 9,157 feet (2,791 m) above sea level and receives 18 inches (46 cm) of precipitation annually.

Sky islands are isolated mountains surrounded by radically different lowland environments. The term originally referred to those found on the Mexican Plateau and has extended to similarly isolated high-elevation forests. The isolation has significant implications for these natural habitats. The American Southwest region began warming up between c. 20,000 and 10,000 years BP and atmospheric temperatures increased substantially, resulting in the formation of vast deserts that isolated the sky islands. Endemism, altitudinal migration, and relict populations are some of the natural phenomena to be found on sky islands.