We evaluated wildlife use of witches' brooms associated with infection by Douglas-fir dwarf mistletoe (Arceuthobium douglasii) in 6 mixed-conifer study areas in Arizona and 2 areas in New Mexico. We climbed 153 infected Douglas-firs (Pseudotsuga menziesii) and examined 706 witches' brooms for evidence of wildlife use. Even though we observed evidence of use by birds, most wildlife use was by small mammals, particularly red squirrels (Tamiasciurus hudsonicus). Red squirrels used witches' brooms for nesting, foraging, caching, and as latrines. Witches' brooms classified as Type II or III brooms, located close to the main bole with large platforms, and 5–10 m above the ground were the most frequently used by red squirrels.