- The Mount Graham Red Squirrel (Tamiasciurus Fremonti Grahamensis) is a critically endangered subspecies found exclusively in the isolated "sky island" high-elevation forests of the Pinaleño Mountains in southern Arizona north of Willcox - As of December 2025, the population is estimated at approximately 234 individuals, holding steady despite a dry calendar year - They are tiny, weighing about 8 ounces and measuring roughly 8 inches in length with a 6-inch tail ... they are grayish-brown with rusty markings on their backs and a white belly; unlike other red squirrels, they lack a white-fringed tail - Their diet primarily consists of conifer seeds from pine, fir, and spruce cones, as well as mushrooms and fungi - Both males and females are highly territorial, defending a midden—a large central food cache made of cone scales where they store seeds for winter - Unique among red squirrels, they are largely silent except when sounding an alarm, which is described as an explosive...