Colorado is a state in the Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains. The 2020 United States Census enumerated the population of Colorado at 5,773,714.
A process of extirpation by trapping and poisoning of the gray wolf from Colorado in the 1930s saw the last wild wolf in the state shot in 1945. A wolf pack recolonized Moffat County, Colorado in northwestern Colorado in 2019. Cattle farmers have expressed concern that a returning wolf population potentially threatens their herds. Coloradoans voted to reintroduce gray wolves in 2020, with the state committing to a plan to have a population in the state by 2022 and permitting non-lethal methods of driving off wolves attacking livestock and pets.
While there is fossil evidence of Harrington's mountain goat in Colorado between at least 800,000 years ago and its extinction with megafauna roughly 11,000 years ago, the mountain goat is not native to Colorado but was instead introduced to the state over time during the interval between 1947 and 1972. Despite being an artificially-introduced species, the state declared mountain goats a native species in 1993. In 2013, 2014, and 2019, an unknown illness killed nearly all mountain goat kids, leading to a Colorado Parks and Wildlife investigation.
The native population of pronghorn in Colorado has varied wildly over the last century, reaching a low of only 15,000 individuals during the 1960s. However, conservation efforts succeeded in bring the stable population back up to roughly 66,000 by 2013. The population was estimated to have reached 85,000 by 2019 and had increasingly more run-ins with the increased suburban housing along the eastern Front Range. State wildlife officials suggested that landowners would need to modify fencing to allow the greater number of pronghorn to move unabated through the newly developed land. Pronghorns are most readily found in the northern and eastern portions of the state, with some populations also in the western San Juan Mountains.
Common wildlife found in the mountains of Colorado include mule deer, southwestern red squirrel, golden-mantled ground squirrel, yellow-bellied marmot, moose, American pika, and red fox, all at exceptionally high numbers, though moose are not native to the state. The foothills include deer, fox squirrel, desert cottontail, mountain cottontail, and coyote. The prairies are home to black-tailed prairie dog, the endangered swift fox, American badger, and white-tailed jackrabbit.